Concrete Contractor April/May 2016 by ForConstructionPros.com

Is There a Future for Fabric-Formed Concrete Structures?

12 April/May 2016

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How to Manage MOISTURE LOSS AND TEMPERATURE of Freshly-placed Concrete

Basalt Fiber Reinforced

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WHAT’S INSIDE

April/May 2016 | Issue 3, Volume 16

Cover Photo Credit: Neuvokas Corporation

Departments 4 Editor’s Letter 6 Legal Matters 36 Foundations Q&A 50 The Last Placement

Cover Story 8 Basalt Fiber Reinforced Rebar Fibers play an ever increasing role in concrete construction.

40 A Decorative Mix for Diamond Polishing

Features

Producing an overlay topping mix for the diamond polishing industry.

12 Is There a Future for Fabric-Formed Concrete Structures? Part two in a two-part series details some of the obstacles to its uses as architects, engineers and contractors have yet to embrace this forming method.

18 Equipment Specification Guides: Screeds A compilation of technical information when choosing your next screed.

28 Pumps and Placement Equipment

46 Things to Consider When Choosing an Overlay 30 How to Manage Moisture Loss and Temperature of Freshlyplaced Concrete Curing, the action taken by contractors to maintain adequate moisture and temperature of freshly-place concrete, promotes the chemical hydration of the cementitious materials within the concrete.

What’s Online

When considering if an overlay is right for your facility or client, it’s important to paint wide brush strokes of possibilities, but root expectations in the complexities of the install.

48 Prepare Early for OSHA’s Silica Dust Regulations The Occupational Safety and Health Administration has issued a final rule on silica dust exposure.

Read these online exclusive articles at www.ForConstructionPros.com/concrete.

Soaring in Sugarland, Texas with Fogle Aviation

A compilation of products.

Flowcrete Americas and STAR applicator partner DLS Floors have successfully completed a large polymer floor installation at a private aircraft hangar located in Sugarland, Texas. Search: 12183667

Formwork Allows Bridge to be Concreted in One Pour A 91-ft.-long, 19-ft.-wide bridge had to be concreted in one pour to ensure the structure would act as a portal frame. Search: 12163048

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EDITOR’S LETTER

Innovation Drives the Market

nnovation is a vital driver for any business to evolve and grow. As contractors continue to take on more work, manufacturers continue to produce innovative products, contributing to the success of contractors. This month’s cover story features a profile on Neuvokas Corporation, a manufacturer of basalt fiber reinforced rebar (BFRB). While the use of basalt fibers is not new, the product this company is manufacturing and their hope to offer a significant contribution to the industry is. Turn to page 8 to learn more about how this new product may be a cost effective competitor to steel rebar. In another innovation, Diamatic has developed a decorative mix designed specifically for diamond ground finishes. Turn to page 40 to learn more. We had planned to run a piece featuring innovation from the contractor’s perspective. George Lacker of Couture Concrete Systems, Plantation, Florida, has been a contractor for 40 years. Over the years, he had spent his time experimenting and tinkering with various concrete elements trying to

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Published and copyrighted 2016 by AC Business Media Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording or any information storage or retrieval system, without written permission from the publisher. CONCRETE CONTRACTOR (USPS 021-799, ISSN 1935-1887 (print); ISSN 2471-2302 (online) is published 7 times a year: January, February/March, April/May, June/July, August/September, October/November and December by AC Business Media Inc., 201 N. Main Street, Fort Atkinson, WI 53538. Printed in the U.S.A. Periodicals postage paid at Fort Atkinson, WI, and additional entry offices. POSTMASTER: Send address changes to Concrete Contractor, PO Box 3605 Northbrook, IL 60065-3605 April/May 2016. Issue 3, Volume 16

Search: Concrete Polishing

Dennis Purinton Purinton Builders, Inc. East Granby, Conn. Joe Reardon Diamatic Orlando, Fla.

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Vaughn Rockhold, (800) 538-5544, ext. 1248 vrockhold@ACBusinessMedia.com Ryan Olson, (800) 538-5544, ext. 1306 rolson@ACBusinessMedia.com Kim Basham, Jim Baty, Brad Humphrey, David C. Whitlock, Joe Nasvik Cindy Rusch April Van Etten Wendy Chady Angela Kelty

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come up with “a better mouse trap.” Sadly, we learned at press deadline, he had passed away suddenly. George was larger than life. He was an innovative contractor who conceived big ideas, and had aspirations to improve the decorative concrete market. He wanted to bring craftsmanship back to the decorative concrete work. Looking back at some of the projects he worked on, George was a true craftsman. We intend on running the profile about George in a future issue. But for now, we say goodbye and remember the larger than life moments that George brought with him when he entered a room. He will be missed, but his contributions to the industry and the people he met along the way will serve as his legacy.

Jim Cuviello Cuviello Concrete Polished|Stained|Crafted Stevensville, Md.

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LEGAL MATTERS

David C. Whitlock has over 25 year’s experience in business immigration, compliance, employment counseling and training. He is the founding attorney of Whitlock Law LLC and can be reached at (404) 626-7011 or at davidcwhitlock@gmail.com.

By David Whitlock

Contractors Beware: New Rules and Regulations Coming Soon New overtime rules, a change in the labor law and more.

early all contractors will have begun placing concrete by the time you read this. Although this means that you will be very busy during the season, you still need to watch for certain legal developments that are likely to impact your business. Every contractor will need to address the new overtime rules which are about to be published by the Department of Labor’s Wage and Hour Division. These new rules will probably not affect your field labor, but will impact your office staff and front-line supervisors. In the past, you have been able to treat as exempt anyone in an administrative or managerial job who was paid a salary of $455 per week. The proposed rule will increase the salary requirement to at least $970 per week for this year. Worse, the minimum salary for exempt status will increase each year as the cost of living increases. In essence, this means that anyone earning less than $51,000 this year will likely not be exempt from overtime. Here are a couple of things that you can do now to prepare for this change. Identify those workers who will need to be reclassified as non-exempt once the new rules take effect. Once you have identified affected workers, you need to put a plan in place that will pay them properly under the law, but not cause a loss of employee morale. One way to do this is to pay these employees a

hourly wage that takes into account how much overtime they now work. It is vital, however, that you watch these newly non-exempt workers’ hours to ensure they do not work overtime in the future. Dr. David Michaels, the head of OSHA, was quoted as stating that the Walking Working Services and Personal Fall Protection Systems final rule will likely be published before he leaves office at the conclusion of the Obama administration. Finally, Michaels praised OSHA’s new severe injury reporting rule and the congressional approval of increase penalties for OSHA citations. The Equal Employment Opportunity Commission (EEOC) has become far more aggressive in a number of areas. This past January, the EEOC issued updated guidance that will make it easier for employees to bring retaliation claims that will be harder for employers to defend against. This particular guidance adopted a court’s broad standard, stating that a causal connection between an allegedly retaliatory action and the underlying protected activity can be established by a “convincing mosaic of circumstantial evidence.” Contractors should carefully review all adverse employment actions to ensure that there is no retaliation. One change that the EEOC has implemented that has yet to be fully appreciated is that the EEOC will now permit a charging party to obtain a copy of, and rebut, the employer’s position statement. The

EEOC’s stated policy is to make their investigative process more open, but the impact upon contractors remains to be seen. It is likely that more claims will go to litigation as the agency cannot decide who is telling the truth. In addition, the EEOC is focusing upon protection for individuals with HIV, protection of Muslims and persons of Middle Eastern descent, and protection of LGBT individuals. The EEOC is pushing very hard to make sexual orientation discrimination equivalent to sex discrimination covered by title VII. In two lawsuits recently filed, EEOC has asserted that a gay man and a lesbian employee for each subject it to hostile work environment discrimination because of their gender. The National Labor Relations Board (NLRB) is also aggressively seeking to change labor law in favor of unionized workforces. The Board is doing this in some subtle ways, for example by narrowing the definition of who is a supervisor under the law. For most contractors, it is likely that the Board would find that your foreman are not statutory supervisors. Thus, it is important that contractors ensure that form and in fact exercise independent judgment and discretion in directing their employees. There are other changes at the state and federal level that may impact your business. Therefore you must stay alert and, where possible, prepare in advance for coming changes.

6 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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Basalt Fiber Reinforced Polymer (BFRP) rebar is new technology that holds good promise for the construction industry. Basalt rock is heated to a molten stage and formed into the fibers you see at the lower part of the photo. Then they are mixed with epoxy resins and molded into the rebar shown above. Photo Credit: Neuvokas Corporation

Basalt Fiber Reinforced Rebar Fibers play an ever increasing role in concrete construction.

he Fiber Reinforced Polymer (FRP) rebar industry is about thirty years old. The industry started by molding aramid and carbon fibers with various thermoset resins, and then expanded to glass fibers mixed with both vinyl ester and polyester resins. It focused the majority of its time on glass fibers as they offer the best price of the three fibers mentioned. Glass fibers come in three types: • E-glass fibers – Low resistance to high pH (such as concrete environment). • Corrosion resistant (CR) glass fibers – Same strength as E-glass with improved alkali resistance. • S-glass – Higher strength and alkali resistance. As standards and usage guides have been developed by the American Concrete Institute (ACI) the FRP rebar industry has continued to grow and is found in many applications today. About three years ago Erik Kiilunen started exploring the possibility of making FRP rebar using basalt fibers and along with

co-founder Ken Keranen started the Neuvokas Corporation, Ahmeek, Michigan. Their product is basalt fiber reinforced rebar (BFRP) and they are calling their new product “Gatorbar” with sales starting in November of 2015. At this early juncture Neuvokas is only pursuing slab-on-grade and other “low engineered” markets while long-term testing is being completed.

FIBERS FROM BASALT ROCK The quest to invent a fiber made from basalt rock goes back to the mid 1920’s when Paul Dhe of Paris, France received US Patent 1462446 A. In the 1970’s U.S. glass companies abandoned their development efforts to use basalt fibers in favor of S-Glass. It was in 1984 when the first commercial continuous basalt fiber (CBF) operations were established at a factory located near Kiev, Ukraine. Shortly thereafter the technology was declassified and released to the world. CBF is now manufactured in Russia, Ukraine, China and Ireland. The process of making the fibers involves crushing and washing basalt rock and then heating it to 2,550 degrees Fahrenheit. The fluid rock is then extruded through multiple tip bushings to make fiber 13 to 19 microns or .0005 to .0007 inches in diameter. Basalt fibers are not toxic to water

or air, will not react with any of the components of concrete and have a very high chemical resistance. Compared to other fibers such as S-glass, carbon or aramids used in concrete, they are also considered to be inexpensive.

GATORBAR BFRP REBAR CHARACTERISTICS Tensile Strength: Guarantee is 145,000 psi, average is 164,000 psi. (grade 40 steel is 70,000 psi and grade 60 is 90,000 psi) Modulus of Elasticity: 6.7 Msi (steel rebar is 29 Msi) Currently being produced: #3 bar (3/8 inch diameter) Weight: .09 lb./ft. (approximately 1/7th as much as #4 steel rebar) Expected life: Unknown, but greater than 60 years. Ambient temperature effect: The coefficient of thermal expansion of GatorBar is very close to concrete resulting in very little differential expansion between the two materials. Corrosion Resistance: BFRP is resistant to almost all forms of corrosion.

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By Joe Nasvik

MAKING BASALT REBAR Most FRP rebar is made using the pultrusion process (a continuous manufacturing process of pulling composite materials with constant cross-section through a die) to wet fibers typically using vinyl-ester or polyester resins. Neuvokas worked out its own pultrusion process and Kiilunen adds that they preferred to use epoxy resin because of its advantageous properties. In the Neuvokas process basalt fibers are “wetted” with epoxy resin and then bars are shaped and compacted. The cost to produce FRP is very dependent on the manufacturing process speed and the ability to increase output speeds will yield significant cost savings. Kiilunen says

“Engineers need a year’s worth of data before they can design our product into more complicated structural projects and we are currently only one month into a one year testing program being conducted by a neutral party.” When testing is complete Neuvokas will put together design guides to enable engineers to use BFRP in their projects. Neuvokas will also look towards the ACI for further BFRP product acceptance. Kiilunen says their first product is #3 bar (3/8 inch diameter) in 20-foot lengths. Their next introduction will be #3 bars in 40 foot lengths and after that they plan to begin production of both #4 and #5 bars. A problem that all FRP products have is that bars can’t be field bent in the way that steel rebar can. So when engineers require bent bars for an application the bars must be prebent separately at the manufacturing plant. Kiilunen says they plan to provide this service in the future also.

WHY YOU SHOULD CONSIDER USING BASALT BAR

The fibers are between 0.0005 to 0.0007 inches in diameter and are bundled to form strands. Considered to be structural fibers, they have much larger tensional strength than steel. Photo Credit: Neuvokas Corporation

the Neuvokas manufacturing method has been developed to produce rebar over ten times faster than the typical pultrusion process and he thinks they will be able to increase this speed significantly in the future.

A primary goal for Neuvokas is to produce FRP rebar that is superior to steel rebar in many ways but also remain cost competitive with steel, perhaps even costing less in some

COVER STORY

applications. Their invention of a high-speed manufacturing process has helped them achieve this goal. As Neuvokas continues to increase its productivity the cost of FRP rebar will continue to go down. The low cost of their product compared to other FRP products and steel is a reason owners and contractors should consider its use. Additionally in some cases the high tensile strength of BFRP allows engineers to switch project requirements from #4 steel rebar to #3 BFRP, allowing additional cost savings. Corrosion resistance is another good reason to consider using BFRP rebar; it’s resistant to almost everything. Due to recent corrosion studies of epoxy coated rebar installed in corrosive climates, engineers are increasingly specifying rebar made from stainless steel or galvanized steel rebar and other more non-corrosive products such as FRP rebar. Compared to FRP and these other metal products BFRP offers great cost advantages. Rebar weight is another reason to consider buying this product. You can ship seven times more product for the same cost and workers can assemble BFRP rebar mats easily, and then safely lift them into final position. On a recent parking lot project

The bars aren’t deformed the way steel bars are but their rough irregular surface provides a good bond to concrete. Photo Credit: Neuvokas Corporation

LOOKING TOWARD THE FUTURE Given that Gatorbar is a new product Kiilunen says their first marketing effort is to the slab-on-grade market. This includes floors, sidewalks, curbs, gutters, other paving projects, and other “low-risk” projects in terms of the engineering required.

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COVER STORY The worker shown here is using a pneumatic device that shoots a plastic tie clip to join sections of rebar together, a fast way to assemble mats. Photo Credit: Neuvokas Corporation

The contractor for this project set-up a layout mat on top of an asphalt parking lot to quickly and accurately assemble rebar mats. One of the big advantages of using BFRP rebar is its light weight. Two workers can easily lift 20 x 20 foot mats and move them to the placement location.

Photo Credit: Neuvokas Corporation

in Houston, Texas, workers set up layout jigs to assemble 20 foot by 20 foot mats with bars spaced on 12 inch centers, both ways. The completed assemblies weighed only 50 pounds and were easily lifted into position by two workers—safe and fast. A primary reason for including rebar in slab-on-grade floors and pavement is to control both the amount of cracking in a slab and crack widths. BFRP has a much

lower modulus of elasticity than steel rebar and this can be used to the engineer’s advantage. When slabs are properly designed, BFRP rebar can reduce the total number of cracks while keeping crack width within AASHTO specifications.

CLOSING THOUGHT Basalt is one of the most common rocks on the planet, and is the only ingredient needed to make basalt fiber. In terms of corrosion

or degradation there is almost nothing that affects it. GatorBar’s superior strength, low weight, zero corrosion, and finally product cost when compared to steel allow FRP rebar to be used in new applications. As more testing is completed and more design aids become available to help engineers include BFRP rebar in projects, its use will become more widely accepted.

10 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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CONCRETE FORMING

By Robert P. Schmitz, M.S.ST., P.E.

Is There a Future for FabricFormed Concrete Structures?

PART 2 This is Part 2 of a twopart article on the use of flexible formworks for forming concrete structures. Part 1 appeared in the February/ March 2016 issue of Concrete Contractor and introduced this unique method of forming concrete. This article will focus on some of the obstacles to its use as architects, engineers and contractors have yet to embrace this forming method as a replacement for or an addition to their conventional formwork systems.

paper by D. Veenendaal et al.1 gives a detailed historical perspective of innovators who have proceeded us using fabric as part of their building forming systems, as hydraulic and geotechnical structures, as form liners and as the membrane in their pneumatic formed

structures. Most influential were those innovators who used woven geotextiles for their civil engineering works such as revetments, underwater pile jackets, pond liners and coastal and river structures. Their research found that geotextiles offered superior concrete finish and durability, had exceptional strength and were a very economical way for

Figure 1. Exterior view of the Schultz Residence . Photo Credit: Sandy Lawton

containing concrete.2 Additionally were those applications where fabrics, used as form liners, were also shown to improve the surface

12 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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CONCRETE FORMING quality and finish of the cast concrete member. They set the stage for today’s researchers. Throughout the 20 th century, a number of innovators experimented with fabric as a flexible membrane for the support of fluid concrete, forming structural members. Despite decades since visionaries such as Heinz Isler and Antoni Gaudi used hanging chains and fabrics to visualize their shell structures, computational analysis still presents a challenge for structural members cast directly into a flexible membrane.3, The author and several others 4, 5 have explored the analysis of these complex forms.6, 7, 8 My research involved the development of an FEM (finite element method) procedure to design a fabric cast wall panel.9, 10 Straightforward methods of analysis and design are available for the conventionally cast concrete wall or

floor panel. This is not the case for the wall panel cast in a flexible fabric formwork. It bears worth repeating that while it is true that a flexible fabric formwork may be used nearly anywhere a rigid formwork is used, a significant amount of research remains to be done to bring these systems into everyday practical use by the construction industry. Standards and guidelines for using flexible fabric formworks need to be developed for the design community to take full advantage of this unique method of forming concrete members and feel comfortable using it. We recognize that wood and/or metal used for forming will not be eliminated by using fabric but can be reduced to essential components thereby saving natural resources. There are a number of issues and hurdles to be overcome before

architects, engineers and especially concrete contractors are accepting of this unique method of forming concrete. While geotextile fabric as a formwork has a number of distinct advantages including: • The possibility to form very complex shapes. • It is strong, lightweight, inexpensive, reusable and will not propagate a tear. • Less concrete and reinforcing are required resulting in a conservation of materials. • Filtering action of the fabric improves the surface finish and member durability. 2, 11, 12 It also has several disadvantages including: • Relaxation can occur due to the pre-stress forces in the membrane. • The potential for creep in the geotextile material, which can

14 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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be accelerated by an increase in temperature as might occur during hydration of the concrete as it cures. • The concrete must be placed carefully and the fabric formwork not jostled while the concrete is in a plastic state. However, until new fabrics are developed the benefits of using geotextiles far outweighs any disadvantages. In addition, unless standards and guidelines for use in precast and cast-in-place forming systems are developed this method of forming concrete will remain a niche market exploited only by those brave and bold enough to challenge the status quo. To be of practical use to the design community some standardization of systems and guidance are needed for contractors to feel comfortable using flexible formworks.

After reviewing recent e-mail correspondence from three of the leading proponents of fabric formwork regarding their thoughts on the future of fabric-formed concrete, Richard Fearn of Fab-Form Industries and Professors Remo Pedreschi and Mark West I get the impression that making an immediate and significant industry impact is indeed difficult. All three indicate that the very nature of the marketplace is complex and that for the builder, who may be selected solely based on his/her low bid, he/ she may be reluctant to take on an unknown system. There is a risk involved when pursuing new means of construction. However, Professor Pedreschi says we should not see fabric formwork as a replacement but a new “disruptive technology” that offers us the opportunity to design formwork in a new way.

CONCLUSIONS To date, three fabric-formed concrete conferences have been held. From these dedicated conferences have come more than 75 papers and presentations on this topic. Therefore, it would appear, from at least the international scene, the movement, if it can be called that, is alive and well. Is there a future for fabric-formed concrete structures? Given the current level of research and enthusiasm that was expressed at the most recent conference; the answer is maybe. Architects, engineers and contractors have yet to embrace this forming method as a replacement for or an addition to their conventional formwork systems. The current disconnect between academia and industry needs to be overcome. From a practical point of view, the answer may be one where fabric formworks do not replace but supplement conventional

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CONCRETE FORMING forming methods. This fabric forming concrete method has special properties, structural advantages unique to its use as outlined above and we fully expect to see it grow beyond the “niche” or novelty forming method marketplace it currently occupies. It will just take collaboration with industry and time. Ed. Note: An Introduction to Fabric-Formed Concrete for Architectural Structures - Part 1 appeared in the February/March 2016 issue of Concrete Contractor. Readers interested in additional information are encouraged to visit the following websites: • Author’s research dedicated website: http://www.fabwiki. fabric-formedconcrete.com/ • The International Society of Fabric Forming (ISOFF): http:// www.fabricforming.org/ Robert P. Schmitz, P.E. is a registered professional engineer

REFERENCES: 1. Veenendaal, D. & West, M. & Block, P. 2011. History and overview of fabric formwork: using fabrics for concrete casting. Structural Concrete: Journal of the fib, 12 (3): pp. 164–177. 2. Lamberton, B.A. 1989. Fabric Forms for Concrete. Concrete International. 11 (12): pp. 58-67. 3. Chilton, J. 2012. Form-finding and fabric forming in the work of Heinz Isler. In: Orr, J., Evernden, M., Darby, A. & Ibell, T. (eds.) icff 2012: Proceedings of the Second International Conference on Flexible Formwork, ICFF 2012, 27-29 June 2012, Bath, UK. University of Bath, BRE CICM. pp. 84-91. 4. Bechthold, M. 2008. Innovative Surface Structure Technologies and Applications. Abingdon, Oxon & New York: Taylor & Francis. 5. Billington, D.P. 1983. The Tower and the Bridge. New York: Basic Books, Inc. 6. Bhooshan, S. & El Sayed, M. 2012. Sub-division Surfaces in Architectural

in the State of Wisconsin, USA with more than thirty-five years experience in architecture and structural engineering. His research interest in fabric formwork comes as a result of work he completed for his Master’s degree and his desire to see this unique method of forming concrete brought into mainstream

Form Finding and Fabric Forming. In: Orr, J., Evernden, M., Darby, A. & Ibell, T. (eds.) icff 2012: Proceedings of the Second International Conference on Flexible Formwork, ICFF 2012, 27-29 June 2012, Bath, UK. University of Bath, BRE CICM. pp. 64-74. 7. Veenendaal, D. & Block, P. 2012. Computational form-finding of fabric formworks: an overview and discussion. In: Orr, J., Evernden, M., Darby, A. & Ibell, T. (eds.) icff 2012: Proceedings of the Second International Conference on Flexible Formwork, ICFF 2012, 27-29 June 2012, Bath, UK. University of Bath, BRE CICM. pp. 368-378. 8. Veenendaal, D. 2008. Evolutionary Optimization of Fabric Formed Structural elements. Master’s thesis, Delft University of Technology, Delft, the Netherlands. 9. Schmitz R.P. 2004. Fabric-Formed Concrete Panel Design. Master’s thesis, Milwaukee School of Engineering, Milwaukee, Wisconsin.

Figure 2. View of stripped formwork (left) and insulation cavity (right). Photo Credit: Sandy Lawton

construction practice. He is a member of ASCE and ACI. He can be reached via e-mail at rpschmitz@ rpschmitz.com.

10. Schmitz R.P. 2006. FabricFormed Concrete Panel Design. In: Charney, F.A. & Grierson, D.E. & Hoit, M. (eds.) Proceedings of the 17th Analysis and Computation Specialty Conference, 2006 Structures Congress, 18-21 May 2006, St. Louis, Missouri. CDROM published by American Society of Civil Engineers. 11. Abdelgarder, H.S. & El-Baden, A.S. 2012. Effect of fabric types on the compressive strength of concrete. In: Orr, J., Evernden, M., Darby, A. & Ibell, T. (eds.) icff 2012: Proceedings of the Second International Conference on Flexible Formwork, ICFF 2012, 27-29 June 2012, Bath, UK. University of Bath, BRE CICM. pp. 20-24. 12. Delijani, F. 2010. The Evaluation of Changes in Concrete Properties Due to Fabric Formwork. Master’s thesis, Department of Civil Engineering, University of Manitoba, Winnipeg, Canada.

16 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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Equipment built on concrete experience. Wacker Neuson makes a full range of professional concrete trowels ranging from the 24-inch edger to the 10-foot hydraulic rider. But thatâ&#x20AC;&#x2122;s not all, we go the extra mile. With over 25 years of engineering and manufacturing experience, a team of national product specialist and a technical training academy, Wacker Neuson is the brand you can trust and your partner for the long run.

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SPECIFICATION GUIDE: SCREEDS

Screeds

A compilation of technical information when choosing your next screed. Hand and Spin Screeds

1 The EZ Screed Complete Tool Set

The EZ Screed Tool is designed for walks, driveways and slabs of various sizes. The EZ Screed Tool used in an upright position is faster and more effective in the leveling of concrete, resulting in a more precise, professional finish to your concrete job while minimizing stress on back and knees as in the traditional method of screeding. Features: Powder coated handle with stand, quality aluminum blades (3 to 7 lbs. each), lightweight and durable. ForConstructionPros.com/10080016 Model

Weight (lbs.)

Blade Lengths

Handles

EZ Screed Complete Set

5 lbs. per handle, 1 lb. per foot for aluminum screeds

3’, 4’, 5’ and 7’ aluminum screeds

Powder coated steel handle

Model

Weight (lbs.)

Blade Lengths

Handles

5 lbs. per handle

Will attach to any 10’ to 20’ aluminum or wood screed

Powder coated steel handles

EZ Screed Pro Two

2 EZYSCREED with Inbuilt Level

EZYSCREED is a manual screed, featuring an inbuilt level and reversible capabilities. It is lightweight with a designed screeding edge and reinforcements, making it the most useful, economical and strongest screed on the market. Available in lengths from 0.9 m / 2’11” to 3.6 m / 11’9”. ForConstructionPros.com/12003790 Model

Weight (lbs.)

Blade Lengths

Handles

EZYSCREED

Multiple weights

Multiple

3 Spin Screed Rugged Screed

The durable and dependable Spin Screed levels concrete fast and flat and has been chosen by thousands of contractors worldwide. Pour more durable concrete faster and flatter by using the Spin Screed. The company sells a variety of accessories including a plastic chairs screed bar support system that reduces the fill volume by 85% when compared with a pipe screed. ForConstructionPros.com/10084911 Model

Weight (lbs.)

Blade Lengths

Handles

Spin Screed

13 lbs. (with T handles 16 lbs., 22’ of aluminum pipe, less than 100 lbs.)

Uses pipe and can handle a variety of lengths up to 22 ft.

T-handles

18 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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4 Kraft Tool BuckEye Straightedge

The BuckEye Straightedge is a one-person screeding tool. Made for striking off, leveling, and bringing concrete, sand and other building materials to the surface grade. Available in six sizes from 4’ to 12’. Featuring a top reading spring loaded level vial for easy on-the-job adjustments, and a tapered wood handle with three hand-holes for a smooth comfortable grip. Made of lightweight high-grade 100% aluminum alloy. ForConstructionPros.com/10079589 Model

Weight (lbs.)

BuckEye Straightedge

Multiple weights

Blade Lengths

Handles

4’, 5’, 6’, 8’, 10’, 12’

Wood handle with built-in level vial

Model

Weight (lbs.)

Blade Lengths

Handles

Magnesium Keyhole Hand Screed

Various weights

10’, 12’, 16’, 20’

Model

Weight (lbs.)

Blade Lengths

Handles

Magnesium Super Flat Paver’s Straightedge

Multiple weights

8’, 10’, 12’, 16’

Aluminum 10’ button handle with insert

Wet Screeds

Pneumatic LBG 800 Bull Float 1 Chicago and LBG 1200 Screeds Chicago Pneumatic offers two new walk-behind screeds—the LBG 800 bull float screed and LBG 1200 hand-held screed—that are light and easy to handle. They are designed to provide a consistent, even surface without any guide or supporting tube. Equipped with a reliable Honda engine, the screed features a rubber element to reduce H/A vibrations. For quick adjustments, the ignition switch and throttle control are within easy reach for the operator. ForConstructionPros.com/12057796 Model

Weight (lbs.)

Engine/Motor Manufacturer

Engine/Motor (horsepower)

Displacement

Blade Lengths

Handles

Tank Capacity

CP LBG 800 Bull Float Screed

40 lbs.

Honda GX25 Mini 4-Stroke Engine

1.1 hp

25 cm4

84”

Three snap-lock sections, extending up to 180 in.

.61 U.S. qt. / (0.58 Liters)

Model

Engine/Motor Manufacturer

Engine/Motor (horsepower)

Displacement

Blade Lengths

Handles

Tank Capacity

Honda GX35 4-Stroke Engine

1.3 hp

35.8 cm3

48”, 72”, 96”, 120”, 144”, 168”, 192”

Two adjustable handles

.67 U.S. qt./ (.63 Liters)

Weight (lbs.)

CP LBG 1200 Hand- 6 lbs., up to 26 lbs. (six Held Screed models available)

2 MQ Whiteman DuoScreed

The MQ Whiteman DuoScreed delivers versatile performance and portability in compact package. Extruded aluminum blades are available in 6’, 8’, 10’, 12’, 14’ and 16’ widths and feature distinct cutting edges for wet-screed or form-to-form applications. A dependable and easy starting Honda GX-35 gasoline engine drives the eccentric weights and weighs only 32 lbs. The DuoScreed is ideal for striking off medium to high slump concrete in residential, municipal or commercial applications. ForConstructionPros.com/10079949

Model

Weight (lbs.)

Engine/Motor Manufacturer

Engine/Motor (horsepower)

Displacement

Blade Lengths

Handles

Tank Capacity

MQ Whiteman DuoScreed

Power Unit - 32 lbs., blade 1.9 lbs./foot.

Honda

1.3 hp

35 cc

6’, 8’, 10’, 12’, 14’, 16’

Twin Folding

.65 liters

www.forconstructionpros.com/concrete | April/May 2016 | Concrete Contractor

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SPECIFICATION GUIDE: SCREEDS Wet Screeds Continued

3 Multivibe MVPR100H

Joe Lindley, owner of Jlin Corp. DBA Multivibe has an impressive background in the art of working with concrete. He had 20 years of experience as a contractor prior to his 26 years of design/building equipment for concrete placement. Listening to customers is why Multivibe has the largest selection. All of the company’s products are designed and built with the Multivibe quality on focus. ForConstructionPros.com/ 12189542 Model

Weight (lbs.)

Engine/Motor Manufacturer

Engine/Motor (horsepower)

Displacement

Blade Lengths

Handles

Tank Capacity

Multivibe MVPR100H

Honda

1.5 hp

35 cc

Up to 24’

Option: Single or Two

.6 qts.

4 Allen HD7070 Magic Screed

The Magic Screed is a precision engineered, lightweight wet screed for single operator strike-off of concrete. Fast and easy to use, this high-frequency screed provides uniform distribution over the entire blade length, enhancing structural integrity of the concrete through consolidation. ForConstructionPros.com/12057778 Model

Weight (lbs.)

Engine/Motor Manufacturer

Engine/Motor (horsepower)

Displacement

Blade Lengths

Handles

Tank Capacity

Allen HD7070 Magic Screed

36 lbs.

Honda

1.5 hp

35 cc

4’ to 16’ in 2’ increments

Adjustable

.67 qt.

Model

Weight (lbs.)

Engine/Motor Manufacturer

Engine/Motor (horsepower)

Displacement

Blade Lengths

Handles

Tank Capacity

Allen EPU36V

36 lbs.

N/A - 36 V battery

N/A

4’ to 16’ in 2’ increments

Adjustable

N/A

5 MBW SCREEDEMON

From a health and safety viewpoint, the SCREEDEMON lowers wet screed hand/arm vibration by between 50 and 90 percent. Hand/arm vibration is linked to a number of occupational health problems including white finger, carpel tunnel syndrome, and chronic arthritis. the link between engine and eccentric is a low cost, very durable, flex coupler. High maintenance flex-cables or rigid shafting is eliminated. the SCREEDEMON couples to its screed bar via a compression lock. The magnesium screed bar is designed to work within the natural frequency of the screed/bar combination. The back-to-back double triangular design is very rigid and offers comparatively uniform vibration along the full length of the bar. ForConstructionPros.com/10083973 Model

Weight (lbs.)

Engine/Motor Manufacturer

Engine/Motor (horsepower)

Displacement

Blade Lengths

Handles

Tank Capacity

ScreeDemon WS500H

29 lbs. (power unit only)

Honda

GX35

1.9 in3

4’ up to 24’

N/A

0.17 gal.

6 Somero S-940 Wet Screed

Introducing the Somero S-940 Wet Screed Machine, driven by versatility and simplicity with increased power and productivity. The S-940 features a 10’ auger screed head with the ability to screed on chaired mesh, chaired rebar, heat tubes, some slab on deck and more. An optional 9’ raking/fine grade head for raking concrete, finish grading or spreading material is available. The machine features a fold-able elevation beam for narrower profile during transport or entry onto jobsites. An optional 3-D Profiler System is also available. ForConstructionPros.com/12189731 Model

Weight (lbs.)

Engine/Motor Manufacturer

Engine/Motor (horsepower)

Displacement

Blade Lengths

Handles

Tank Capacity

S-940A

1,775 lbs. (805kg) - Diesel engine with 10’ head; 1,653 lbs. (750kg) with 10’ head

Subaru EH65 or optional Kubota DH902 Diesel

22 hp (Subaru) or 24.8 hp (Kubota)

N/A

10’; 11’3” with Auger Motor

N/A

4 gal.

20 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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SPECIFICATION GUIDE: SCREEDS Wet Screeds Continued

Neuson Wet Screed Now Available 7 Wacker with Magnesium Boards

Wacker Neuson’s wet screed is now available with a full line of magnesium boards. Magnesium is a strong, lightweight metal that will reduce the weight of the boards by over 25 percent compared to aluminum boards. The full line of magnesium boards is available in seven different lengths: 6’, 8’, 10’, 12’, 14’, 16’ and a 2-meter option. All the magnesium boards have a 4.9” width and range in weight from 9.8 lbs. to 25 lbs.. The boards are easily connected to the wet screed system. ForConstructionPros.com/12058112 Model

Weight (lbs.)

Engine/Motor Manufacturer

Engine/Motor (horsepower)

Displacement

Blade Lengths

Handles

Tank Capacity

P35A Wet Screed

34.2 lbs.

Honda GX35

1.6 hp

2.2 in³

4’ to 16’

Twin handle

0.7 qts,

Power Screeds

1 Somero S-10A Laser Screed

Introducing the Somero S-10A Laser Screed machine, driven by an unparalleled pursuit to be the best, this machine will help your operators make the most of every pass. The machine can be transported via flatbed or tag-behind trailer. It is a fully automated-self-leveling 10’ screed on a 20’ telescopic boom. The Quick GradeSet System can easily and accurately set grade in minutes. The OASIS Laser Control System can fine-tune and calibrate from the command center. ForConstructionPros.com/12189729 Model

Height (inches)

Width (inches)

Weight (lbs.)

Boom Coverage

S-10A Laser Screed

5’ 11”

6’ 8”

7,500 lbs.

20’

Engine/Motor (Mfg & Horsepower

# of Drive Wheels

Machine Zero Turn Drive Capable

Fuel Type

N/A

Diesel

wheel drive with Proportional Kubota 35 hp Diesel TwoJoystick & Hydraulic Motors

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22 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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Power Screeds Continued Model

Height (inches)

Width (inches)

Weight (lbs.)

Boom Reach

Engine/Motor (Mfg & Horsepower

# of Drive Wheels

# of Steer Wheels

Tank Capacity

S-22 Laser Screed

8’ 1”

7’ 2”

8,796 lbs.

20’

Duetz 74 hp, Tier 4i plus auxiliary power unit

4 wheel drive

2 wheel/4 wheel/ crab steer modes

12 gal.

Model

Height (inches)

Width (inches)

Weight (lbs.)

Boom Reach

Engine/Motor (Mfg & Horsepower

# of Drive Wheels

# of Steer Wheels

Tank Capacity

S-485 Laser Screed

4’

3’-7-1/2”

1,107 lbs.

Unlimited, no boom

Honda 20.8 hp

4 wheel drive

4 wheel steer

4.25 gal.

2 Ligchine International ScreedSaver BOSS 240

Like every ScreedSaver model, the BOSS 240 includes standard features of Wireless remote control, fully automatic operation, 2D laser control and 3D satellite control (optional). The BOSS 240 may be hauled with a pickup truck/trailer combination. According to the company, the BOSS 240 will produce FL numbers that can only be achieved by using a boom operated screed. The BOSS offers 240 square feet of coverage per pass with an 18’ boom combined with a 13.5’ Superflat screed head. Standard on the BOSS is a liquid additive spray bar on the screed head that includes an on-board spray tank and automatic ON/OFF activation. ForConstructionPros.com/12164074

Model

Height (inches)

Width (inches)

Weight (lbs.)

Boom Coverage (sq. ft. per pass)

Engine/Motor (Mfg & Horsepower

# of Drive Wheels

Machine zero turn drive capable

Fuel Type

ScreedSaver BOSS 240

66”

82”

7,095 lbs.

240

Kubota 57 hp

Yes

Gasoline or optional LP

multi-purpose solution

The Rotator KP 40 is the multi-purpose solution to your surface preparation needs. The propane powered Rotator has a full range of interchangeable tooling to make all your surface prep jobs faster and easier. Tooling includes ﬂail grinders, shavers, polishing grinding heads and coating removal heads.

Dickson Industries Inc. www.roadproonline.com

www.rotatorsolutions.com

www.forconstructionpros.com/concrete | April/May 2016 | Concrete Contractor

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SPECIFICATION GUIDE: SCREEDS Power Screeds Continued Model

Height (inches)

Width (inches)

Weight (lbs.)

Boom Coverage (sq. ft. per pass)

Engine/Motor (Mfg & Horsepower

# of Drive Wheels

Machine zero turn drive capable

Fuel Type

ScreedSaver II

54”

2,840 lbs.

130

Honda 20 hp

Yes

Gasoline

Model

Height (inches)

Width (inches)

Weight (lbs.)

Boom Coverage (sq. ft. per pass)

Engine/Motor (Mfg & Horsepower

# of Drive Wheels

Machine zero turn drive capable

Fuel Type

ScreedSaver MAX XT

62”

76”

4,500 lbs.

200

Kubota 35 hp

2 All Terrain Tracks

Diesel

Truss Screeds

1 Allen SE12 Steel Truss Engine Driven Screed

The Allen Razorback Truss Screed is the contractor’s preferred brand when high tolerance FL Numbers are specified on concrete floors and pavements. For more than 40 years, Allen Truss Screeds have set the industry’s standard for precision levelness, rigidity and durability. Allen Engineering has a full line of truss screed models and accessories. Allen’s commitment to quality and customer satisfaction will insure that your truss screed will provide years of trouble-free operation. ForConstructionPros.com/12057760 Model

Height (inches)

Max Width (ft.)

Max Weight (lbs.)

Engine/Motor (Mfg & Horsepower

Tank Capacity

Allen SE12 Steel Truss Engine Driven Screed

N/A

65’

180 lbs.

N/A

Model

Height (inches)

Max Width (ft.)

Weight (lbs.)

Engine/Motor (Mfg & Horsepower

Tank Capacity

Allen SA12 Steel Truss Engine Driven Screed

N/A

65’

186 lbs.

N/A

Model

Height (inches)

Max Width (ft.)

Weight (lbs.)

Engine/Motor (Mfg & Horsepower

Tank Capacity

Allen AE12 Aluminum Truss Engine Driven Screed

N/A

50’

90 lbs.

N/A

2 Speed Screed Cruiser/Speed Screed HEAVY DUTY

Metal Forms Corporation offers two concrete finishing models: The Speed Screed Cruiser and the Speed Screed Heavy Duty to satisfy all concrete finishing job demands. The Heavy Duty model is designed for high production, low slump paving operations. The Cruiser model is the most popular model for all types of finishing projects.

• Reversible “double life” aluminum finishing tubes* • Variable width up to 75’ • Self-contained power source • Positive crown control

• Lift handles for easy transport • Forward travel by either hand winches or hydraulic winches ForConstructionPros.com/12189180

Model

Height (inches)

Max Width (inches)

Weight (lbs.)

Engine/Motor (Mfg & Horsepower

Tank Capacity

Speed Screed Cruiser

16”

14”

11 lbs. per ft.

5.5 hp / Honda Engine, 8 hp Honda Engine

5 gal.

Model

Height (inches)

Max Width (inches)

Weight (lbs.)

Engine/Motor (Mfg & Horsepower

Tank Capacity

Speed Screed Heavy Duty

27”

24”.

20 lbs. per ft.

8 hp Honda Engine/13 hp Honda Engine

10 gal.

24 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

CONC0416_18-27_SpecGuides.indd 24

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Truss Screeds Continued

3 MBW Blitzscreed

The MBW Blitzscreed is a lightweight aluminum screed designed for flat, inverted or crowned applications up to 65’. Available section lengths include 8’, 4” 4’,4”; and 2’, 4”. The diagonal truss/A-frame system offers structural strength while the flexcouplings and turnbuckle design makes for quick assembly and disassembly. Blind nuts help keep concrete off threads and eases disassembly/assembly. Hydraulic winches are also available. ForConstructionPros.com/12057874 Model

Height (inches)

Width (inches)

Weight (lbs.)

Engine/Motor (Mfg & Horsepower)

Tank Capacity

MVS Mechanical Blitzscreed

16”

15”

8.3 lbs./ft.

Up to Honda GX270 (8.5 hp)

5.6 Qts.

Model

Height (inches)

Width (inches)

Weight (lbs.)

Engine/Motor (Mfg & Horsepower)

Tank Capacity

AVS Air Blitzscreed

16”

15”

8.9 lbs./ft.

N/A

4 MQ Whiteman WS-HE Series Vibratory Truss Screed

The WS-HE Series vibratory truss screed from MQ Whiteman features a modular design that delivers outstanding results in flat work or bridge deck applications. Sections are available in 2’, 2.5’, 5’, 7.5’ and 10’ spans featuring all steel truss construction and durable galvanized blades. Engine driven models offer a choice of 9 hp or 11 hp Honda engines, manual or hydraulic winches. The powered option with manual winches is ideal for low slump concrete. ForConstructionPros.com/12189440 Model

Height (inches)

Width (feet)

Weight (lbs.)

Engine/Motor (Mfg & Horsepower

Tank Capacity

MQ Whiteman Truss Screed

N/A

2.5’, 5.0’, 7.5, 10’ sections

Varies

9.0 HP, 11.0HP

N/A

CUT and BEND REBAR At the Shop or Jobsite

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Portable #6 bar cutter/bender

Replacement blades for most brands

www.RebarBlades.com

Quality rebar equipment since 1979

FASCUT Industries Inc. (608) 643-6678

www.fascut.com

www.forconstructionpros.com/concrete | April/May 2016 | Concrete Contractor

CONC0416_18-27_SpecGuides.indd 25

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McKrete $0.46 - $.90/sq. ft

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PRODUCT FOCUS

PUMPS AND PLACEMENT EQUIPMENT

LD100 Concrete Placing System The updated, remote-controlled Line Dragon Concrete Placing System increases safety and reduces labor costs by replacing the need for workers to drag and manipulate the concrete pump line and placing boom. • Placer drags the end of the concrete delivery line and places the concrete while the Dragger is hooked 20 ft. back carrying excess line and keeping it out of the placing area. • Allows two men to handle 60 to 80 ft. of 4-in. hose or 40 to 50 ft. of 5-in. hose. • 1,200-lb. system is light enough to place on decking, suspended rebar mesh and just about anything you can walk on. ForConstructionPros.com/11173291

Liebherr 37 Z4 XXT Concrete Pump Truck Liebherr mounted the pipeline for its 37 Z4 XXT concrete pump close to the 3121.4-ft. Z-fold boom to balance the weight. • XXT-narrow outriggers pivotmounted to allow setup with a narrower footprint for access to restricted work sites • Outriggers secured directly to the boom pedestal to bypass truckframe torsion load. • Choice of pumps offer maximum flow rates of 163, 180 and 213 cu. yds. per hour. • Large-radius pipe bends (10.8 in.) reduce pressure loss. ForConstructionPros.com/12039743

Carbon Fiber Concrete Boom - CIFA K45H Whether you need a light restoration or your floor needs more extensive repairs and grinding. Niagara has the equipment, tooling, training and know how to get the job done.

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Irving Equipment is offering a new model of the carbon fiber concrete boom, the CIFA K45H. The first three booms are fabricated from highstrength steel and the last two sections are made from carbon fiber. • 5-section R-Z style boom system with Valme 5-in. metric pipe along the entire length. • HPG 1408-IF9 has an output of 185 yards per hour (1,160 PSI) using 9-in. pistons and a 9-in. S-tube. • Cutting ring and wear plate are easily serviced from inside the hopper without moving the S-tube. • Comes standard with an HBC brand remote control system which includes a main and a back-up handset. • Rear panel uses a touch pad covering so concrete, water and chemicals cannot penetrate the control box. • The K45H installed on a 4-axle chassis weighs about 73,000 lbs. ForConstructionPros.com/11362586

SEARCH for more information online using the unique URL under each product.

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Olin Engineering 5 220CA Pump Olin Engineering, Inc. has pushed CFA Pile grouting to the max with its latest version of the 5 200CA, the 5 220CA. According to the company, Olin is the most commonly used pump in the CFA or “Auger Cast” Pile Deep Foundation industry. • Powered by a 260 hp Cummins and 250cc of Kawasaki hydraulic pump, it will empty 10 yard loads of structural grout mixes in under three minutes. • The company builds five models exclusively for the application from 75 to 200 yph. • A complete line of stationary concrete, shotcrete and ½” minus aggregate ball valve pumps are available. ForConstructionPros.com/12061229

Schwing Adds Tier 4 Engine SP 500 Stationary Pump Schwing is now providing their popular SP 500 stationary concrete pump with a Tier 4 compliant Caterpillar diesel engine. This is a response to government-mandated reductions in harmful exhaust gases from diesel-powered equipment. The California Air Resource Board (CARB) requires Tier 4 compliance for stationary pumps used on public and private projects. Other parts of the country are also requiring Tier 4 compliance depending on the locale and project. The CAT C3.4B diesel is rated at 74.5 hp while providing durability and fuel efficiency. The SP 500 is a versatile machine with up to 45 cubic yards per hour output and 1100 psi maximum pressure on the material. ForConstructionPros.com/12178572

Putzmeister Upgraded Thom-Katt Trailer Pump Line The TK 40, TK 50, TK 60 HP and TK 70 trailer pumps feature a relocated fuel tank and a new control box with display. • Fuel tank relocation featured on single- and tandem-axle units to allow for increased ground clearance for better access over rugged or uneven terrain. • Control box provides for a more active presentation of pump information, diagnostics and an emergency run mode. • Designed to handle harsh mixes and a variety of difficult applications. • Offer easy filling and operation, fast setup and simple cleanup. ForConstructionPros.com/12085007

FLOOR GRINDING JUST GOT EASIER

Zim-Mixer Volumetric Concrete Mixer Zim-Mixer volumetric concrete mixers are available in capacity sizes ranging from 4 to 14 cu. yds. • Can be custom designed to meet specifications. • Patented dual chain material feed system • Provides ability to run materials independently. • Meet ASTM C685 and VMMB standards. • Model shown features a 9-cu.-yd. capacity with a production rate of 60 cu. yds. per hour. ForConstructionPros.com/10208159

Need a consistent finish on your project without sacrificing productivity or fatiguing operators? Husqvarna’s NEW PG 680 RC and the PG 820 RC are two very highly productive and powerful grinders with outstanding ergonomics. The remote control is key on these machines. It enables the operator to move around the jobsite and can also optimize the grinding parameters to assure quality. The PG 680 RC and PG 820 RC feature a new, exclusive automatic oscillation function. This ensures the best possible grinding pattern. It creates a flatter floor as well as eliminating the need to cross-hatch. Scan the QR code to to learn more or visit www.husqvarnaCP.com to schedule a demonstration. husqvarnaCP.com

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CONCRETE SCIENCE By Kim Basham, PhD PE FACI

Curing Part II –

How to Manage Moisture Loss and Temperature of Freshlyplaced Concrete Curing, the action taken by contractors to maintain adequate moisture and temperature of freshly-place concrete, promotes the chemical hydration of the cementitious materials within the concrete.

s discussed in Curing Part I – Why cure? (January 2016), curing is a critical concreting step that strongly influences the hardened concrete properties including strength, permeability, abrasion resistance, shrinkage, resistance to freezing and thawing and deicing chemicals, especially in the curing-affected zone or the near surface of the concrete. There are many curing methods available for the initial, intermediate

and final stages of curing concrete as shown in Figure 1. Initial curing occurs anytime between placing and final finishing of the concrete with the purpose of reducing the loss of moisture from the concrete. Final curing, between final finishing and the end of the curing period, reduces the loss of moisture from the concrete and controls

the temperature of the concrete. Intermediate curing occurs between the final finishing and the start of the final curing and is typically required when the surface is too soft to start the final curing process. Curing methods shown in Figure 1 consist of either adding water to the surface of the concrete after final set or techniques to minimize

Figure 1. Methods of Curing METHOD

STAGES OF CURING Initial

Intermediate

Sunshades and windbreaks

✔

Fogging*

✔

Liquid-applied evaporation reducers

✔

Final

Sprinkling with water*

✔

Ponding

✔

Wet burlap, cotton mats and synthetic covers*

✔

Wet sand, straw or hay

✔

Plastic sheeting or reinforced paper*

✔

Liquid membraneforming compounds*

✔ ✔

*Applicable to vertical surfaces (walls, columns, beams, etc.)

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moisture loss from the surface of the concrete. Regardless of the curing method used, curing consists primarily of managing moisture loss and temperature of the freshly placed concrete. While some of the curing methods listed in Figure 1 are applicable for vertical surfaces such as walls, columns and beams, the listed methods are primarily recommended for horizontal surfaces including interior and exterior slabs. Curing vertical concrete surfaces is less critical than curing horizontal surfaces. Because vertical surfaces are free draining and difficult to saturate, they are less prone to environmental attacks such as freeze/ thaw damage. [For curing of vertical surfaces, see the insert box, page 33.] Unlike vertical surfaces, horizontal surfaces such as floors and exterior flatwork must be hard and durable to resist wear from forklift, pedestrian and vehicular traffic and/or damage from exposure to freezing, thawing and deicing chemicals.

maintained to prevent surface drying of the concrete. As the humidity above the slab increases, the rate of evaporation from the concrete decreases. Standing upwind, direct the fog spray above the slab so the mist settles onto the slab creating a reflective or wet appearance on the surface. On a windy day, frequent or continuous fogging may be required. It is okay if water accumulates on

the surface of the concrete as long as the water does not mar, penetrate or erode the surface. Adding water to the surface by fogging is equivalent to replacing the bleed water that prematurely evaporated. Treat the accumulated water just like bleed water. Don’t finish the accumulated water into the concrete. Remove or allow the accumulated water from fogging to evaporate before finishing.

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SUNSHADES AND WINDBREAKS In most cases, erecting sunshades and windbreaks is easier said than done. For most projects, sunshades and windbreaks are not practicable or efficient options for protecting concrete from rapid evaporation and moisture loss. However, placing concrete indoors or under-roof is a workable and preferred option versus placing outdoors or in the open where the freshly placed concrete is defenseless against the ambient conditions. It is considerable easier and more economical to control moisture loss and to maintain proper concrete temperatures under-roof. In general, installing floors under-roof produces a higher quality product.

FOGGING By forcing water through special nozzles that atomize the water into a fog-like mist, the relative humidity above the slab can be increased and

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CONCRETE SCIENCE LIQUID-APPLIED EVAPORATION REDUCERS When sunshades, windbreaks and fogging are not practical, applying an evaporation reducer (retarder) to the surface of the concrete after strike off and between the different finishing operations can help prevent surface drying. Similar to sunshades, windbreaks and fogging, evaporation reducers can minimize the risk of plastic shrinkage cracking and surface crusting. Evaporation reducers are waterbased mixtures containing chemical compounds that form an oil-like film over the surface of the concrete that reduce the evaporation rate of the bleed water. The effective time of these products is limited and depending on the rate of drying, time of concrete set and finishing operations, repeat applications may be required. Because evaporation retarders are about 90 percent water,

they should not be worked into the surface of the concrete to restore the workability of the surface paste. Doing so will increase the water to cementitious materials ratio (w/cm) along the surface reducing both the quality and durability of the concrete.

SPRINKLING WITH WATER AND PONDING After final set, applying clean water by sprinkling (garden sprinklers and soaker hoses) or ponding provides excellent curing. However, these methods are difficult to use because of the challenges associated with obtaining an ample source of clean water, dealing with water runoff and building dikes or dams along the edges of slabs. If used, water must be free of harmful amounts of deleterious materials and impurities that will attack or stain the concrete. Also, the concrete must be sufficiently hardened so the surface is not damaged nor the

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surface paste diluted by premature application of the water.

WET BURLAP, COTTON MATS AND SYNTHETIC COVERS A more practical means of applying water for final curing is wet burlap, cotton mats or other absorbent materials. These materials can wet cure by holding and supplying water to both horizontal and vertical concrete surfaces. Regardless of the material used, keep material saturated throughout the cure period and consider covering with plastic sheets or tarps to reduce the rate of evaporation. When using burlap, thoroughly rinse with clean water before placing on the concrete to minimize the risk of concrete staining, do not let the burlap dry or it will absorb moisture from the concrete and always dry before storage to avoid mildew and rot that may affect the next job.

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32 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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CURING OF VERTICAL SURFACES Leaving the forms in place is the most common approach to limit moisture loss from walls, columns and sides of beam. However, leaving forms in place for an extended time period (three to seven days) ties up the formwork causing both construction delays and an increased inventory of formwork. Either can increase construction costs. Form facing materials must be non-absorbent (metal or sealed plywood, etc.) to minimize moisture loss from the surface of the concrete. Otherwise, facing material can absorb moisture from the concrete creating soft, chalky and discolored surfaces. If needed to prevent premature moisture loss or required by the contract documents, sprinkling vertical surfaces with water, applying wet burlap, plastic sheeting or liquid membrane-forming compounds can extend the curing period after formwork removal.

WET SAND, STRAW AND HAY

For commercial and industrial slabs, curing covers consisting of synthetic fabrics and bonded whitepigmented polyethylene films have become extremely popular due to the easy application, moisture retention and curing efficiency. Due to the polyethylene film, typically no additional water is required after the initial wetting, even for a seven-day cure period.

Wet sand, straw and hay are still viable options for wet curing but burlap, cotton mats and synthetic covers are more efficient, less likely to cause staining or discolorations of the concrete and provide more uniform curing. When using sand, it must be clean and thick enough (greater than ½ inch) to hold water uniformly over the slab. For straw and hay, thickness

should be at least six inches and kept wet throughout the curing period to prevent concrete drying and to avoid the danger of fire.

PLASTIC SHEETING AND REINFORCED PAPER Based on entrapping moisture within the concrete, plastic (polyethylene) sheeting, waterproof reinforced paper and liquid membrane-forming compounds reduce evaporative water loss from the surface of the concrete. For plastic sheeting, use a minimum thickness of 0.004 inches. Use white colored sheeting during hot weather and black for cold weather concreting. White sheeting minimizes heat gain by absorption of solar radiation and black sheeting maximizes heat gain. When the as-cast appearance is important, plastic sheeting may not be the best curing choice.

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CONCRETE SCIENCE Plastic sheeting can cause patch discolorations or a mottled appearance due to variations in moisture and temperatures beneath the sheeting, especially if the sheeting becomes wrinkled. Periodically flooding the concrete under the sheeting can help minimize surface discolorations. Reinforced paper is installed similar to plastic sheeting and like plastic sheeting, holes and tears should be repaired and if needed, the concrete re-wetted under the sheeting. For exterior applications and some interior applications, special attention is required to anchor or secure the sheeting to avoid the wind from tunneling under or displacing the sheeting.

LIQUID MEMBRANE-FORMING COMPOUNDS These compounds are commonly referred to as spray-on curing

compounds and work by forming a surface membrane that seals moisture into the concrete. Curing compounds are very effective and the preferred curing method for large surface areas or areas that are difficult to cure using other curing methods. Typically, these compounds consist of waxes and/ or resins emulsified in water or solvents. Water-based compounds have become more common because of the VOC or volatile organic compound emission regulations. There are many different types and classes of curing compounds formulated for different applications. Be sure to read and understand what type and class of curing compound has been specified for your job. Curing compounds must be applied uniformly and at the manufacturer’s recommended rate. For small areas, apply curing compounds with a wide, soft-bristle brush or paint roller.

For large areas use a power sprayer with the appropriate wand and nozzles as recommended by the manufacturer of the curing compound. Apply curing compounds immediately after the disappearance of the surface water sheen following the final finishing or texturing. Delayed application allows drying of the surface and increases the likelihood the curing compound will be absorbed into the surface instead of forming a water-retention membrane on the surface. If needed, re-wet the surface and allow drying to achieve a uniform damp surface before applying the curing compound. Regardless of the curing method used, do not allow the concrete to dry during the curing period. If surface drying occurs, immediately re-wet the surface. Unfortunately, dry concrete will not absorb sufficient external water to restore the internal moisture loss.

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FOUNDATION Q&A

By James R. Baty II

Now a Structural

Concern Concrete contractors have been forming with aluminum forms for more than 60 years and there are specific constructability issues and performance recommendations that validate and maintain the effectiveness of this method of forming.

uestion: I constructed a basement foundation for a home owner last week with a new set of aluminum forms we had just received. With work increasing I didn’t have the time to wait for pre-treatment on the forms and I didn’t have the chance to condition the forms like I would have normally. After the forms were stripped, the owner contacted us through the architect to inform us that they had structural concerns for

the condition of the wall and expected us to tear the walls out or provide an approval from a licensed engineer endorsing the walls for performance – Foundation Contractor (Arkansas).

NSWER: Thank you for directing this technical inquiry to our attention. As Executive Director for the CFA and as Chair for the ACI 332 Residential Concrete Committee responsible for ACI 332XX Requirements for Residential Concrete, I have been part of this conversation of aluminum and concrete for quite some time. I am repeatedly surprised by the design industry’s lack of understanding for the issues related to aluminum and concrete and positioning with an overly-conservative viewpoint. You have asked my interpretation of the building code issues as they relate to the presence of aluminum as a forming material for concrete. I can tell you, with absolute certainty, that there is no provision of a current building code, commercial or residential, that prevents the use of aluminum forms for any concrete construction method, including that of vertical cast-in-place walls. The primary references for residential codes, or mandatory compliance would be the IRC1 and

Lines formed by the bubbling and subsequent movement of hydrogen at the interface of new, untreated aluminum forms and concrete prior to initial set are commonly misunderstood as cracks. This wall is more than fifteen years old and exposed throughout its duration with no protective coating. It is a yard wall formed for the sole purpose of pre-treating new aluminum forms, a process they no longer use due to manufacturer pre-treatments. ACI 332-142 . A common statement in the IRC can be found in R402.2 Concrete: …Materials used to produce concrete and testing thereof shall comply with the applicable standards listed in Chapters 19 and 20 of ACI 318 or ACI 332. Before moving on to ACI 332, however, note that in the IRC, Section R404.1.3.3.6 Form materials and form ties, states: …Forms shall be made of wood, steel, aluminum, plastic, a composite of cement and foam insulation, a composite of cement and wood chips, or other approved material suitable for supporting and containing concrete. Here direct reference is given to the acceptability and general practice of cast-in-place forming for residential wall construction using aluminum forms.

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FOUNDATION Q&A The first official release of a concrete code for new construction other than ACI 318 was ACI 332-04, designed to be a companion code to the projects under the jurisdiction of the IRC. A review of ACI 332’s residential concrete code notes that there is zero reference to aluminum offered in the discussion throughout the document. Aluminum is not a common structural element seen used or attempted for use to be embedded in concrete walls (e.g. an anchor bolt or wind strap). This is because the code is minimum requirements only. ACI 332 produces another document, ACI 332R3 where the committee does discuss the presence of aluminum in proper use for concrete construction. Section 3.7.2 Metal, states: …Aluminum that has not been treated or properly cured for use in forming concrete will produce a reaction with the alkali resulting in

a damaged finished surface. These forms can be chemically treated or cured through a minimum of two contacts with concrete placements to prevent the affected surface conditions. To be noted here is the reference to “finished surface” as the finished surface is not the structural condition for the wall. ACI’s Concrete Terminology, the common definition standard for all ACI documents provides two guiding definitions: Finish — The texture of a concrete surface after consolidating and finishing operations have been performed. Finishing — Leveling, smoothing, consolidating, and otherwise treating surfaces of fresh or recently placed concrete or mortar to produce desired appearance and service. The finish, the surface condition of a concrete element is cosmetic and an issue of durability (i.e.

frozen concrete affecting freeze/ thaw cycling durability) rather than affecting the inherent nature of the structural performance. The primary technical issue is that a reaction between aluminum and concrete produces hydrogen that results in one of two concerns, the hydrogen bubbles try to work out of the concrete surface and create lines, trails or pocks and if sustained contact lasts long enough, the aluminum cross-section itself is reduced…not that of the concrete. There is no report or evidence in any building code authority or in technical guide reference to corroborate a concern for the structural integrity of the concrete when in contact with aluminum rather than aluminum that has been embedded. In fact, ACI 303R-044 states: Aluminum, magnesium, and zinc all react with alkaline material in

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38 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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REFERENCES: concrete, liberating hydrogen gas that causes sticking and bubbling on forms containing these metals. Extreme care and attention is needed to minimize these effects. Therefore, these materials should not be used to produce architectural concrete. It is for these purposes, that aluminum form manufacturers offer pre-treated aluminum forms or concrete contractors condition their new forms with several non-exposed or test placements until the raw aluminum has been conditioned to be non-reactive with the concrete. The surface condition for any concrete wall placed with untreated aluminum forms is a surface that can, if necessary or required be finished just like any standard concrete architectural element that has remediation work to be performed. There are a variety of patching components that are available for the finish work

1. 2012 International Residential Code For One- and Two-Family Dwellings published by the International Code Council, Inc., 4051 West Flossmoor Road, Country Club Hills, IL 60478-5795 | Phone 1-888422-7233 | www.iccsafe.org 2. Residential Code Requirements for Structural Concrete (ACI 332-14) and Commentary published by the American Concrete Institute, 38800 Country Club Drive, Farmington Hills, MI 48331 | Phone: 248-8483700 | www.concrete.org

on exposed concrete surfaces. Otherwise, any waterproofing or other coating will more than suffice in completing the work for long term, durable performance of nonexposed conditions. A cosmetic issue with a wall should never be a condition for failure to approve the structural performance unless it is first investigated by a licensed design professional that is fully knowledgeable of the conditions for the service of the structural element. However, contractors should always

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3. Guide to Residential Concrete (ACI 332R-06) published by the American Concrete Institute, 38800 Country Club Drive, Farmington Hills, MI 48331 | Phone: 248-8483700 | www.concrete.org 4. Guide to Cast-in-Place Architectural Concrete Practice (ACI 303R04) published by the American Concrete Institute, 38800 Country Club Drive, Farmington Hills, MI 48331 | Phone: 248-848-3700 | www.concrete.org

inform their client of the finished condition that they are prepared to deliver and communicate the options to the client for accepting or upgrading those finished provisions.

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By Joe Nasvik

A Decorative Mix for Diamond Polishing Producing an overlay topping mix for the diamond polishing industry.

hen you are diamond polishing a floor there are a number of factors that will influence the final appearance: ➊ Floor surfaces that aren’t flat take more time to polish and results often shows areas where

Most decorative toppings have only sand aggregate but large aggregates can provide good wear resistance so they are incorporated into this mix. Photo Credit: Diamatic

the grinding cuts into the aggregate while other areas don’t grind deeper than the sand/cement paste layer at the very top. ➋ Concrete below 3,000 psi doesn’t maintain a high polish and can cause excessive diamond wear. While concrete above 4,000 psi is difficult to grind and takes a lot more time to finish. ➌ All the cracks in a floor also show through diamond polish finishes— undesirable to some but acceptable to others who want a more rustic final appearance. ➍ Floors that aren’t level can cause problems for some architectural wall treatments and leveling of freezers or coolers. ➎ Workers in the “puddle” during floor placement push large aggregate down with their feet leaving more cement paste and sand. When diamond polishers grind beneath the surface finish these footprints are exposed and visible. For the above reasons owners and designers often specify overlay concrete products to solve problems. This isn’t to say that overlays don’t have problems, they do. • Many products don’t include large aggregate particles which adds to the hard-wear characteristics of a floor.

Diamond polishing overlay toppings is a significant part of the market so Diamatic, a manufacturer of diamond grinding equipment, decided to develop an overlay product with favorable polishing qualities. Its low shrinkage and hard wearing characteristics, gains strength quickly, and produces a high-polish surface. Photo Credit: Diamatic

• If overlays are integrally colored the resulting appearance can have color streaks in the finish. • Overlay products containing significant amounts of polymer admixtures can be difficult to place and finish, but they tend to level out nicely. • Polymer overlay products often have a soft polymer layer on the finished surface. Diamond polishing operations must grind and remove this layer, metal bonded diamonds must be used this work as hybrid diamond tooling may gum up with the polymer. Resin bonded tooling can cause overheating and soften the polymers. • Map cracking can result from overlay products when high percentages of portland cement are included in the mix. Cracks can also develop due to movement in the subfloor.

40 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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• Due to the surface conditions of the subfloor, proper bonding of the overlay concrete may not be achieved.

DIAMATIC Clark Branum, ULTRAFLOR Program Manager for Diamatic, San Diego, California, says they started manufacturing diamond polishing machines, planers, scarifiers, scrapers, and dust extraction equipment for a world market in 2008. They started making material products when they realized that problems with existing floors could reduce the size of their market. At first they worked with companies that specialized in manufacturing and selling overlay products that included polymer admixtures but soon realized these products didn’t work well for diamond ground finishes. So they made the decision to develop their own product, one free from the issues listed above.

DESIGNING A MIX

produce calcium hydroxide as a by-product of hydration, and there is no Alkali Silica Reaction (ASR) resulting from its use. The product name for this decorative overlay is “PC5614.” The “56” part means that a bag weighs 56 pounds while the number “14” means the yield is 14 square feet if you spread it 3/8 of an inch thick. It was introduced to the market after two years of development and

Surprisingly, Branum says they decided not to include portland cement in their mix, instead they turned to Type C fly ash with additives to manage setting characteristics. This type of fly ash has high-early strength gain characteristics, less shrinkage because the water requirement is only half that needed for portland cement (less cracking), it doesn’t

42 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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Sub-floor preparation and proper application of an epoxy bonding agent with sand broadcast on top. Shown here, workers are being trained how best to do it. Photo Credit: Advantage Flooring

testing. In addition to fly-ash the mix includes large aggregate (an additional 20 percent more can be added if desired), fine aggregate, and no admixtures. Only three quarts of water are needed for mixing.

HOW TO INSTALL IT Branum says they use the International Concrete Restoration Institute (ICRI) surface profile recommendations for sub-floor preparation. Their requirement for this type application is a “Concrete Surface Profile 3” finish which can be achieved by grinding with 18/20 metal bonded diamond tooling. Next comes the application of an epoxy

Rapid Set

bonding material and broadcasting sand on the fresh resin to the point of refusal. After curing approximately 70 percent of the sand can be vacuumed away. The prepared mix is usually screeded using a gauge rake and smoothed once with a trowel. “It sets quickly and can usually be walked on within two to three hours. Diamond grinding can begin the following day but I like to test the surface with a rebound hammer to estimate strength before putting a 1,000 pound grinder on it,” says Branum. Polishing steps usually conclude with an 800 grit diamond finish. Because PC5614 contains no portland cement, no calcium hydroxide is generated and therefore silicate densifier applications have no effect on hardness or surface density. The low water-cement ratio of the mix already causes the final product to be very dense. Compressive strengths of

5,000 to 6,000 psi are typical.

CONTRACTOR EXPERIENCE Billy Saul started Advantage Flooring Incorporated, Hanover, Maryland, 23 years ago to serve the Washington DC area. He says their focus is commercial flooring and they install any kind of floor finish— carpet, tile, linoleum, concrete, and others. Much of their work involves removing old product and installing new so preparation often involves removing glue residues stuck to sub-floors. “We bought our first diamond grinder to remove residue from floors because it was fast,” he says. “That led to attending seminars to learn how to polish concrete and that resulted in a contract to diamond polish a 300,000 square foot floor, making us one of the largest floor polishing companies in our area.” Saul says that a new school

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www.forconstructionpros.com/concrete | April/May 2016 | Concrete Contractor 43

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construction in their area suffered frozen concrete floors, causing them to spall. At first the school district wanted him to install a vinyl tile floor but he persuaded them to consider the Diamatic topping as a less costly option when maintenance costs were calculated over a 25 year period. The owner agreed and this turned out to be their first Diamatic topping application. They had installed polymer topping overlays in the past but there were enough problems with installations that they decided to discontinue their use. Advantage Flooring describes themselves as a leveling and polishing company. Currently a popular look in their area is natural concrete looking floor finishes that meet up with glass walls. But many projects, especially those which have been rehabbed many times, have floors which are neither level or flat—glass walls must sit on level surfaces. So the Diamatic

overlay finish has become an important product for them. Saul cautions that you should plan placements with this product carefully. Polishing sequences should start the morning after placing and finishing because the strength gain is so fast. “You can spend a lot more time polishing when slabs get too hard.”

OVERLAYS THAT DIAMOND POLISH WELL Overlay floor treatments are becoming increasingly important to diamond polishing contractors and this product, which replaces portland cement with fly-ash, has some distinct advantages. There is minimal shrinkage (and cracking), increased stain resistance because it doesn’t react with many things that cause stains, it’s high strength contributes

Smaller projects like this one are mixed by the bag. Each batch is quickly screeded with a gage rake and then smoothed once with a trowel. Grinding can begin the following morning. Photo Credit: Advantage Flooring

to high wear, and large aggregates in the mix disrupt scratch patterning. Saul says the appearance of patches and seams are minimized too, yielding blended continuous results. Diamatic is being careful with their product. If you as a contractor want to install it, you have to get training and be certified first.

44 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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When considering if an overlay is right for your facility or client it’s important to paint wide brush strokes of possibilities, but root expectations in the complexities of the install. By Ryan McBride

describe to creative owners or architects that when an overlay is placed on a slab the old is gone, a new clean canvas is available to accept its proposed new vibrant space with total design flexibility. Meeting the clients expectations hinges on the aggregate effort of a great design, a creative applicator, vetted techniques, and proven product choices. New colors and textures are part of what make great spaces unique.

SELF-LEVELING OVERLAYS There are many facets of overlay or wear surface toppings to discuss if a slab is a candidate for self-leveling, smoothing compounds, isolated patching or skim coating. Let’s explore the path of the self-leveling or self-smoothing, wall-to-wall option for a complete space remodel with color as a top priority. When using a wall-to-wall overlay, designers are

not constrained by the old slab and its past lives. Stains, saw cuts, abuse, poor initial concrete installation do not need to be part of the new spaces story. Full overlays allow for nearly seamless transitions into making a new space new. They also should be valued as a capital improvement to the structure being renovated. The raw overlay material is an important first step in choosing a direction for design. Let’s consider final color goals: For brighter colors like yellows and reds using a white portland base or lighter color material helps with the vibrancy. Ardex Engineered Cements offers a white overlay material (PCT White), while Mapei (Ultratop) and CTS Rapid Sets (Tru) raw color is lighter than many grey overlay materials and will provide an accepting canvas for color. The overlay industry has two major mix types or designs of overlay products. Polymer modified material and cementitous. Each mix type has its own unique tendencies or quirks when installing as a finished floor. Often those same tendencies or quirks are much more evident when adding dye or color. Some of these quirks to watch out for include: stripes or lines from the smoother being pulled across the floor; color shifts batch to batch from seemingly miniscule water variances in the mixes or uneven airflow through the space as the overlay cures. I find clients often are excepting of a less than perfect uniform look

if they are explained at the start of any project that their floor is going to be hand made and colored. Over hundreds or thousands of square feet, some variances are going to be evident, especially when it comes to adding colors. I always suggest a large sample area (10’x10’ minimum) be installed on site prior to approving colors. As each unique applicator or concrete artist’s techniques may vary ever so slightly, it is often difficult to see what the finish surface will look like with a small handheld sample or submittal. This in-place sample also gives the installer an opportunity to show some of the installation field variances that may occur so that the owner expectations are properly met.

POLYMER OVERLAYS Polymer overlays have a tendency to form a film or skin on the surface as they cure. This skin must first be ground off to expose the body of material. The polymer skin on the surface will not allow color to penetrate effectively. Once the surface has been “opened up” the body of the polymer design is still an extremely tight matrix when compared to conventional concrete. This means that color is not readily accepted, especially as the topping cures and strength increases over its initial first few days after placement. My rule of thumb with dyes or stains on polymer toppings: cut soon and dye or stain soon to get as much color as deep as possible. Cementitious overlays react more

46 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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CTS Rapid Set TRU Self-Leveling Overlay is a hydraulic cement-based, self-leveling topping, re-surfacer and underlayment for both indoor and outdoor jobsites. The product cures to a light off-white color. It is ideal for floors that are stained, integrally colored, and those with decorative embedded aggregate flooring. Photo Credit: CTS Rapid Set

like conventional concrete when dyeing or staining. The more porous nature of this mix chemistry accepts color and reacts with densfier and hardening agents more quickly and completely.

INTEGRAL COLOR Adding color into the mix to create an integral topping is sometimes a chosen method among experienced contractors. Specific binders (usually polymers) are used when color is added to the mix water. These pigments are provided in either powder form and are water wettable or are shipped as liquid colorant.

When adding color to the mix water, we have found the best, most uniform color from batch to batch is to create a water/dye holding tank to draw from. It is important to keep this water circulating throughout the entire project. The specific gravity of the pigments is heaver than that of clean water. The pigment will fall out of suspension and rest in the bottom of the tank. Having a small circulation pump running in the bottom of the tank will keep an even color throughout the pour. It has been found that color added to some chemistries of engineered toppings interfere with the mix design. Engineered cement is specifically designed with an exact water cement ratio (some products have a larger workability window than others). If you are considering integral coloring, always contact the manufacturer and discuss best practices with their product. If the manufacturer doesn’t have first hand experience

with a pigment supplier or provide their own colors, don’t be a guinea pig! When it comes to colored overlays and renovating space, the number one goal of a contractor should be the management of expectations from the onset. Every designer has “seen a floor” they can’t wait to incorporate into their next project. Usually the colored polished concrete floor their heart is set on came with a great plan and healthy price tag. Trying to cut corners and save dimes on a colored overlay will always cost dollars to repair at the contractors expense if the initial goals or expectations are not in alignment with a solid specification and plan. Ed. Note: Ryan McBride is a consultant at Polished Concrete Consultants, LLC. He can be reached at ryan@polishedconsultants.com.

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www.forconstructionpros.com/concrete | April/May 2016 | Concrete Contractor 47

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Prepare Early for OSHA’s

Silica Dust Regulations

The Occupational Safety and Health Administration has issued a final rule on silica dust exposure.

by Paul Nguyen eing covered in concrete dust is a reality that many workers face everyday. From cutting and coring to concrete grinding, these floating particles are an unavoidable nuisance. However, as many are unaware, the so called nuisance is more dangerous than meets the eye. The concrete dust, aka crystalline silica, negatively impacts countless lives daily by attributing to silicosis, lung cancer, chronic obstructive pulmonary disease (COPD), and kidney disease. That is why on August 23, 2013, the Occupational Safety and Health Administration (OSHA) proposed new standards to toughen its regulation of silica dust exposure.

But how can such a small speck of dust cause so much damage? Silica dust is a slow acting agent that does not pose a problem until it is too late. Dry concrete grinding or cutting fills the air with harmful silica dust throughout the entire jobsite. Even though all the particles may not be visible to the naked eye, the dust is still present. Silicosis results from exposure to low concentrations of silica dust over a long period of time, which usually spans from ten or more years. This slow process lures contractors into a false sense of hope that their health is unaffected, but their lungs are slowly deteriorating. Lungs are naturally able to filter out regular dust and dirt, but silica dust is too small for the lungs’ filtering system to be effective at least 100 times smaller than ordinary sand found on beaches

and playgrounds. The dust particles are like microscopic shards of glass that damage the lining of lungs, which can cause fluid buildup and scar tissue that cut down your ability to breathe. Unfortunately, there is not a cure for silicosis yet, but it is avoidable by practicing safer methods and using appropriate equipment. With OSHA’s proposed new regulations, they estimate to save more than 600 lives and prevent more than 1,500 new cases of silicosis per year. Currently, the daily permissible exposure limit (PEL) is about 100 μg (micrograms)/m3 for most industries. OSHA is proposing to cut this limit in half to 50 μg/m3, averaged over an eight hour day throughout ever industry. The current standards do not offer enough protection for workers.

48 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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The current PEL for silica was established in 1971, and since then, studies have shown that workers are can still get sick or die when exposed to silica at these permissible levels. The rule would require: ✔ Provisions for measuring how much silica workers are exposed to. ✔ Limiting workers’ access to where silica exposures are high. ✔ Using effective methods and equipment to reduce exposure. ✔ Providing medical exams. ✔ Properly training workers about silica related hazards to name a few. Simple ways to drastically reduce silica exposure are through vacuums, masks and wet cutting methods. Using equipment with an attached vacuum system significantly lowers the possibility of concrete dust escaping into the air. Industrial

vacuums with HEPA filters and strong suction power will provide the best results because they are specifically designed for this line of work. Wearing properly fitted masks are extremely beneficial when limiting silica exposure. Instead of wearing masks that came off the store shelves, invest in a custom fit mask that is specifically designed to block out refined particles like silica dust. Store bought masks are not meant to work effectively against these small particles for long periods of time. Furthermore, one of the most effective methods would be applying water to every cut or grind. By using water to subdue the concrete dust, it alleviates workers from silica exposure. Although some workers may be hesitant to switch to a wet method, there are a few benefits. For example, it helps save the life of the tooling, which in turn saves money. And slurry clean up has been simplified through slurry solidifying

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products like Gelmaxx. The product turns the wastewater into a solid byproduct that is safe to dispose in the dumpster. By taking the time now to slowly improve work practices, invest in proper equipment, and train workers, it will provide a much smoother transition once the rule becomes finalized. Ed. Note: Last month, OSHA issued the final rule on silica dust exposure. The goal of the new rule is to curb lung cancer, silicosis, chronic obstructive pulmonary disease and kidney disease in America’s workers by limiting their exposure to respirable crystalline silica. Paul Nyguen is a representative from GelMaxx Slurry Solutions. He can be reached at Paul@gelmaxxusa. com.

Meet

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Advance Metalworking

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American Technical

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Mapei Corporation USA............ 52

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Concrete Polishing University.... 32

Niagara Machine Inc.................. 28

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www.forconstructionpros.com/concrete | April/May 2016 | Concrete Contractor 49

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THE LAST PLACEMENT: BACK TO BASICS

By Jean Feingold

The Basics of

Wat erproofing Adding foundation waterproofing to a concrete business can increase your profits.

oncrete contractors are always looking for ways to make their businesses more profitable. One service that might be a good fit for contractors who install foundation walls and basements is waterproofing.

GETTING STARTED There are two basic types of waterproofing materials: sheet membranes and sprays, including polymers and elastomeric. A contractor will typically use only one of these waterproofing systems. In deciding between them, contractors need to consider the initial cost of the equipment required to do the work and how long it will take to learn excellent waterproofing techniques. The up-front costs for installing sheet membranes are negligible. The only special equipment needed is a linoleum roller. This roller is used to install the membrane by pressing it firmly against the concrete wall. An angle grinder is also needed to smooth and clean the wall during the preparation process to remove any protrusions from the concrete, but this is a tool most concrete contractors already own. Other equipment includes roller covers, brushes, knives and scrapers, which most contractors have on hand as part of normal concrete work. Getting started with sprayed-on waterproofing is more costly, but still reasonable. A cube van with a bulk tank inside it equipped with a spray

rig, hoses and nozzles can be a good start. Contractors should also consider ladders to get down into the excavation and personal protective equipment including coveralls, respirators and face shields for protection them from the spray material.

LEARNING TO WATERPROOF Manufacturers of spray-on waterproofing systems will usually provide one-day training of how to use the system and how to spray the waterproofing product onto walls properly. If a contractor chooses to use waterproofing membranes, there is generally a learning curve. While it may only take a few days to learn the basics, contractors can expect to not feel completely comfortable until after three to five months. Learning new techniques and observing how the structure is put together so the junctions will be waterproofed correctly is paramount.

SELLING THE SERVICE The benefits of waterproofing are the same regardless of the type of product used. They include protecting the foundation or basement walls from vapor or moisture transmission and preventing efflorescence in the concrete. Waterproofing will prohibit mold and stop any water from coming in through cracks. Many people use their basements as lower level living, so it’s a simple sell to protect their investment in the finished basement.

WARRANTIES Part of what sells waterproofing is the warranty. For below-grade jobs, some contractors offer a three-year warranty. While some manufacturers who have their work inspected and approved by the manufacturer give

a 10-year manufacturer’s warranty. These warranties sometimes vary in length from five-, 10- or 20-year written manufacturer’s warranties depending on the additives and layers of protection chosen by the customer.

PREVENTING DAMAGE TO THE WATERPROOFING Things that happen on the jobsite after the waterproofing is finished can damage it. The waterproofing can be damaged in the backfill process or the wall can be cracked then and damage the waterproofing. If a contractor doesn’t grade the drainage away correctly, water as the potential to pond and eventually find a way in. Correct landscaping, grading and downspouts are needed. To avoid these problems, waterproofers need to talk to the landscapers, excavators and builders about how they should do their work to prevent problems that could affect the waterproofing. Subs who cut holes in the wall for utility lines may damage membrane waterproofing. It is recommended to wait 24 hours for the waterproofing product to cure before back-filling to prevent damage. Take caution however, waiting too long to back-fill can damage membrane waterproofing because excessive ultraviolet exposure can cause the upper portion of the membrane to delaminate.

THE BOTTOM LINE Being able to waterproof concrete foundations makes a concrete contractor more valuable to a home builder or general contractor. Offering a complete package of services saves them money and puts more dollars in the concrete contractor’s pocket.

50 Concrete Contractor | April/May 2016 | www.forconstructionpros.com/concrete

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