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CVEN2101 Engineering Construction School of Civil and Environmental Engineering Year 2010 Semester 2

BARKER STREET LODGE REPORT LINX Construction


TABLE OF CONTENTS ABSTRACT .................................................................................................................................................................. 3

INTRODUCTION .......................................................................................................................................................... 4

1. E XCAVATION .......................................................................................................................................................... 5 1.1 DESCRIPTION OF THE PROCESS ............................................................................................................................... 5 1.2 PERSON AND MATERIALS ESTIMATES ....................................................................................................................... 5 1.3 KEY EQUIPMENT ITEMS USED ................................................................................................................................. 5 1.4 O BSERVATIONS OF THE EFFICIENCY OR IMPROVEMENTS ............................................................................................ 6 1.5 DEFICIENCIES ....................................................................................................................................................... 6 1.6 IMPROVEMENTS ................................................................................................................................................... 6

2. HAULAGE .............................................................................................................................................................. 7 2.1 TRUCK WORKS ..................................................................................................................................................... 7 2.2 MOVING MATERIALS ............................................................................................................................................ 7

3. COMPACTION ........................................................................................................................................................ 8

4. CONCRETE ........................................................................................................................................................... 10 4. CONCRETE PROCESSES .......................................................................................................................................... 11

5. DRILLING ............................................................................................................................................................. 12

REFERENCES ............................................................................................................................................................ 14


ABSTRACT This report shows the construction process of the Barker Street Lodge located in Kensington NSW. The report briefly describes the construction processes of excavation, haulage, drilling, concrete, and compaction in relation to the Barker Street Lodge project. Each process’ equipment requirements and procedures are detailed. From site observations, deficiencies in the processes were noted and possible improvements to the efficiency of these processes have been described.


INTRODUCTION The Barker Street Lodge is the $15mil student accommodation construction project located opposite to the University of New South Wales. The construction is managed and constructed by Linx Group , working alongside with Menai Civil Contractors for earthworks which include excavation, geotechnical reports and water engineering consultation. The project commenced in August 2009 and is still in construction as present, October 2010, the project is planned to complete 14 months from the start date. The Barker Street Lodge construction process will be described briefly though out this report, all information gathered for the detail of this report is found upon information given by Linx Group and Menai Civil Contractors.


1. EXCAVATION Excavation itself is a critical process in many civil projects regardless of their nature whether it is dam or a house being constructed. It involves rigorous calculations of earthwork planning that include current volumes of earth that require moving, cutting, filling and soil tops that need stripping. The process of excavation is the execution of all the necessary moving of earth. This is essential to achieve the desirable gradient of the earth in order for the project to be feasible. Soil excavated needs to be also taken into consideration as the volume of soil changes when it has been excavated but, in the calculation carried out in the Kingsford-Barker St Project, the swell factors and yield factors all equal to 1.

1.1 DESCRIPTION OF THE PROCESS Excavation is the first part of the earthmoving process. Excavation is closely related to hauling and compacting as they are all processes that overlap each other on the production timeline. You first start with excavation which involves the removal of the soil, in the case of the Kingsford-Barker St Project; the soil was comprised of sandy fill and alluvial sands. Then the removed soil is loaded on to the trucks which are hauled to the land-fill. There the earth is dumped and the trucks return to repeat the process. Later after the required gradient and depth is acquired, the compactor will spread and compact the soil evenly. Due to the excavation, the required amount of compaction was reduced. For the project in study, the depth required was 21.5m (AHD) and local water table is at 21.3m (AHD). So the excavation took place 0.2m above the water table.

1.2 PERSON AND MATERIALS ESTIMATES Firstly, from a geotechnical report which was completed by Menai Civil Contractors, the soil that needed to be excavated was comprised of sandy fills, alluvial sands as well as “sandstone gravel, concrete blocks, ceramic and wire fragments� (Geotechnical report, Menai Civil Contractors). The area that needed to be excavated was 2 3 2,741.23 m . The average depth of the excavation was 3.99m. This resulting in a total cut of 11,475.32 m . The 3 3 sandy fills that were cut are equal to 2,278.15m and the alluvial sands cut was equal to 9,197.17m . These values were the proposed values by the consulting engineers. The swell factor of the soil was equal to 1.0, this being due to the poor compaction of the existing soil. There was no top soil that needed to be stripped or replaced as the earth level was being lowered by approximately 4m. Several labours needed to be hired to remove the materials such as concrete blocks by hand during the process of excavation. Consulting engineers highly recommended for these soil, a hydraulic excavator, a front end loader.

1.3 KEY EQUIPMENT ITEMS USED For the current project, a hydraulic excavator was used as it was recommended. To be more precise a backhoe on wheels excavator was used as it was best suited to the project. The advantages for the backhoe include the fact it can excavate and load the sandy fills, alluvial sands as well as rocks. It also well suited for this project as it can excavate below ground level which is highly advantageous for the project. Four excavators were employed during the excavation process to maximise efficiency. All the backhoe 3 excavators had a bucket capacity of 0.5m . The buckets could have been slightly larger in order to increase efficiency but, it would result in a lower precision of excavation which is a necessity since the excavation is taking place close to the water table level. Since four backhoe excavators were employed, two excavators was removing the soil and stockpiling it while the other excavators were loading the stockpiled soil into the trucks for dumping in the land fill.


1.4 OBSERVATIONS OF THE EFFICIENCY OR IMPROVEMENTS Overall the process was highly efficient for the current scenario, but with all projects there were some deficiencies on productivity and there was room for improvement. Some of these deficiencies were not foreseeable and others were expected when the consulting engineering for Menai Civil Contractors had predicted.

1.5 DEFICIENCIES Primary deficiency in productivity is the lack of area for the movement of excavators. This caused due to the close proximities of the neighbouring building which include, residential apartments, childcare centre and the congestive traffic of Barker St. The tracking of the hydraulic excavators was also necessary as the foundation of the neighbouring buildings needed to be monitored as they were all based on the soft sand as was this project. Prior to any excavation could begin, water level data loggers had to be installed to monitor the potential rise in the local water table. This due to the fact the desirable depth was 0.2m above the current levels of the water table. If the water table were to rise due to heavy rain or prolonged rainfall, then the excess water would need to be pumped out temporally for the excavation to proceed. After excavation began the labourers onsite are unable to keep up with the task at hand, as there is much more material than expected that needs to be separated for excavation to proceed. This causes the excavator to stop its operations while waiting for the workers to remove unwanted material, which is minute each time, but accumulates to an important interruption. The weather has a detrimental effect on the productivity of the process at hand, causing a complete washout of the site, thus making the excavator’s job virtually impossible. An added deficiency is due to the wet soil, and the unavoidable entering of trucks in order to be loaded, rain causes the tyres of trucks to cause an immense mess on the road they travel on once leaving the jobsite, increasing the chance of ramifications being employed by authorities. During the project, they had experienced 58 days of rainfall.

1.6 IMPROVEMENTS After thorough analysis, various improvements have been realised. Firstly, the lack of movement due to the close proximity can be improved by creating two access points to the site, instead of one. One access point can be on Barker St (currently existent) and the other access point can be located on the opposite side of the site on Harbourne Lane. The water table level problem is unpredictable but, to increase efficiency constant monitoring will allow the site manager to foresee the rise the in the level and a pump can be employed immediately to minimise the effect of the rise in the water table. There are possible advancements that can be made in terms of labouring. The most obvious and most effective solution to the problem of lack of man-power would be the hiring of more labourers, which will reduce the inefficiency of waiting time for machinery. An extra one or two labourers should be hired; otherwise expenses would be too critical. Rain could stop work for weeks on end, therefore a solution must be found in order to propel the job to completion. A cattle grid and wash bay at the access point could be employed, which cleans the tyres of all trucks upon leaving the site, preventing the risk of any complaints being made or fines received.


2. HAULAGE Haulage refers to the transportation of material between operating locations, and transferring soil or rock between positions of excavation and that of spreading and compaction in earthmoving. Selection of equipment is based on considering different conditions and site characteristic. The different types of haulage equipment used depend on the distance: Short-mid distance: excavation and haulage (e.g. dozer, loader, scraper) Long distance: haulage only (e.g. trucks, wagons)

2.1 TRUCK WORKS Trucks form an integral part of the construction environment as they transport materials to and from the site. They form an important part of many construction processes such as earthwork calculations in determining the amount that can be transported to and from the site and what to do with fill that has been excavated. Menai Civil Contractors were able to efficiently coordinate truck work, saving a considerable amount of time and money for the project. The trucks were used with excavators and loaders for soil haul-off and excavation. Typical building materials hauled on site included; sandy fills, alluvial sands, sandstone gravel, concrete blocks, ceramic and wire fragments. For the cohesive materials, the trailer shapes are conducive for the material to be easily discharged when dumped. Rounded edges kept the material from compacting in corners. Capacities of the tip trucks 3 observed on site at Barker St Apartment Lodge were from 10m . Production cycles for the trucks varied according to fixed and variable times. Fixed times include at the site were, the turn and dump time in moderate conditions was about 1.4min, spotting time is about 0.4mins and loading time will depend on other equipment. The trucks travelled on Anzac Pde and roads in the highly dense Kensington and eastern suburbs traffic conditions restricted by local roads such as the Barker St, so variable time was a significant factor. Due to the nature of the site on Barker St with its limited free space due to the neighbouring buildings, trucks must work concurrently and at the same pace as the rate of excavation to ensure efficient use of resources. It is estimated that 1,200 truckloads were required for excavation. Trucks are also required to transport materials across the site. In this case, cranes were be used to hoist materials in and out of the truck and then hauled where needed.

2.2 MOVING MATERIALS It is important for materials brought into a construction site to be moved efficiently and effectively around the site to avoid double handling and ensure the safe movement of materials. The movement of materials is an ongoing process that is an important part of the project construction as it ties in with the other processes that occur in the construction site. The Barker St Lodge construction site was observed to use a very effective method of moving materials around the site. Through strategic planning and organisation Menai Civil Contractors carried out this process with the use of cranes. The crane plays a pivotal part in moving materials around the construction site as it moves heavy materials when they were brought onto the site to the required location to be fitted or used in construction. It plays an important part in placing prefabricated sections and moving steel members amongst other supplies. The importance of the crane is highlighted in the Barker St Lodge construction site as the inability to store materials due to the restricted size of the site meant that when materials were brought on site, they needed to be moved into the required position immediately. One crane was observed at the site, which were efficient in moving materials around the site, seen by the use of a timetable chart to allocate crane time.


3. COMPACTION Soil compaction occurs when the weight of heavy machinery compresses the soil particles closer together, increasing its density, thereby expelling air from the pore space. Compaction is required to prevent settlement in the soil, increase its strength and load bearing capacity, control volume changes in the soil and lower permeability. These advantages from compaction are desirable in earthwork construction and below building foundations. In sands and gravels, the equipment used vibrates to cause re-orientation of the soil particles into a denser configuration. In silts and clays, a sheepsfoot roller is frequently used, to create small zones of intense shearing, which drives air out of the soil. There are four main compaction methods, impact, pressure, vibration and kneading. The effectiveness of each method depends on the soil type being compacted. Vibration is very effective with granular materials, and it was this method that was employed during the construction of the Barker Lodge due to the soil on site being predominately sand. In the early stages of construction of the Barker Lodge Redevelopment, demolition occurred with the removal of existing buildings, a swimming pool and spa, external pavements, garden beds and trees. A large excavation of 11000 BCM was cut and removed from the site. Sheet pile walls were driven into the sand before excavation using high frequency, vibrating methods to adequately drive the piles into the denser and very dense sands. Sheet piling was used to retain the boundary walls during excavation and construction where adjacent buildings where deemed tolerant to the vibration that occurred during the process. The excavation process is closely linked to compaction and haulage as soil is often excavated from one point on site, hauled, and used as fill to compact in either the same or different site. However there was minimal compaction involved in the Barker Lodge construction due to the large excavation for the underground carpark and basement with nearly all of the excavated material being hauled off site. The sand at the bottom level of excavation had already been exposed to the weight of soil above it prior to its removal. The sand was therefore almost sufficiently compacted and the large process of compaction was reduced to a relatively quick process. After excavation to a depth of nearly 4 metres, the base of the excavation was sitting right on the water table. With 58 rain days on the site so far, the water table was constantly fluctuating. This caused the last of the excavation and the compaction processes to lengthen. To overcome this problem the water was continuously pumped out from the excavation. Following the excavation, the exposed sand subgrade was compacted using a 4 tonne roller, together with moistening of the subgrade, to achieve a minimum density index of 70%. To avoid bogging the roller, the first few passes were carried out with no vibration. Neighbouring buildings where monitored during subgrade compaction to asses vibration levels. If vibration levels were considered excessive, compaction continued using static mode only. To reduce loosening effects in the sands and to provide a suitable working platform, the basement on-grade floor slabs were provided with a sub-base layer of fine crushed rock. This was compacted to a minimum density of 100% of Standard Maximum Dry Density. Compaction on the Barker Lodge site also occurred after backfilling behind free-standing retaining walls and of the demolished swimming pool and spa excavations. All backfilling was required to be carried out in maximum 100mm thick loose layers and compacted to a minimum density index of 70%. It was suggested in the geotechnical report that this compaction should be carried out using a small 1 to 2 tonne deadweight nonvibratory roller, or by using a large hand operated vibrating plate compactor. Each method should be


complemented by moistening of each layer. Hand operated vibratory-plate compactors are better for confined areas and will probably be used in the finishing stages of the overall construction. The geotechnical report also states density testing for a minimum density index of 70% to be carried out using a Dynamic Cone Penetrometer (DCP), with DCP blow counts of at least 5 blows per 100mm below 0.3m depth. DCP testing is conducted according to Illinois Test Procedure 501, in which the number of blows to achieve 150 mm of penetration is counted. The 8-kg weight is raised to a height of 575 mm and then dropped, driving the cone into the soil or other material being tested. The frequency of density testing should be at least one test per two layers per 50m^2 for the backfill compaction and at least one test per 500m^2 for the compaction after excavation. The costs involved for the compaction process in the Barker Lodge Construction are minimal compared to the other major processes of excavation and haulage that were carried out. The largest compaction effort required was carried out with one 4 tonne roller which is a relatively small piece of machinery. Costing was not included for compaction in the information we received from the Barker Lodge site office. This also suggests that the time required to complete the compaction effort was only a couple of days with a few workers needed.


4. CONCRETE As one of the most widely used materials in the world; concrete is a vital component in any construction project. Concrete was used extensively throughout the barker street lodge apartment’s project. Since the majority of the structure is composed of concrete, extreme detail was taken into the properties of the concrete. The concrete mix used consisted of Portland cement mix, aggregates and water with a maximum water to cement ratio of 0.46 and without the use of admixtures .33% of fine and coarse aggregates were used as to minimize the cost of the concrete. The concrete strength is approximately 32 mPa. A slump test was performed onsite to ensure that the correct workability of the cement was obtained with the specific water to cement ratio used. The standards that were followed were the Australian standards AS3600. Reinforced concrete walls have been placed around the building which is separated from the soil using sheet piling. This can be seen in the basement 2 slab plan layout.

During the process of designing the various beams and slabs, deflection limits obtained from the Australian standards were taken into consideration. Using this information, the dimensions of the beams and slabs were able to be determined


4. CONCRETE PROCESSES Batching the materials volume of each component of concrete is determined by dividing the weight of the component by the specific gravity of water multiplied by the specific gravity of that component. This was done at the central batch plant from which the Mixing There are two types of mixing, transit mixed central mixed. In this project, concrete is batched in a central batch plant and transported to the job site in trucks. The contractors responsible for the delivery of concrete were ‘Metromix’, situated in Alexandria. This was not the most economical choice however the close proximity made it feasible. The actual mixing of the concrete is done in the truck on the way to the jobsite so that it is ready to be used at arrival. Transporting Cement trucks were used to transport the ready mixed concrete (RMC) to the jobsite. Placing Concrete Pumps were used in this project as it is able to cover the whole of the worksite and also because large amounts of concrete was used. The pump was fed concrete of uniform workability and consistency at a sustained rated ranging between 7.7-115 m3/hr. Effective pumping distance was horizontal 21 meters. Consolidating Concrete contains a large proportion of air voids and therefore needs to be consolidated. Two Mechanical vibrators were used at a time to achieve this. Finishing This process is essential due to the weakening of the concretes strength during the consolidation stage. Surface strength is important for the floor slabs used in the basement car park as heavy loads will be placed on them (cars) as well as the concrete floors of the apartment levels. Requirements for the finished product was a ‘dense homogeneous mass, completely filling the form-work thoroughly embedding the reinforcement and free of stone pockets and compacted thoroughly’ [C9] A bond breaking material was placed between contacting surfaces at contraction joints. Smoothing of concrete surface was achieved using an aluminium magnesium float Curing Curing of all concrete was a achieved by keeping surfaces continuously wet for a period of 3 days, and preventing the loss of moisture for a total of 7 days followed by gradual drying out. Some problems that arose included assigning workers to hold up traffic while the cement trucks were unloading cement. This was due to limited space on site and lead to traffic congestion on Barker Street. Productivity was hard to estimate due to unpredictable traffic conditions. Relationship to other processes Curing of all concrete was a achieved by keeping surfaces continuously wet for a period of 3 days, and preventing the loss of moisture for a total of 7 days followed by gradual drying out. Some problems that arose included assigning workers to hold up traffic while the cement trucks were unloading cement. This was due to limited space on site and lead to traffic congestion on Barker Street. Productivity was hard to estimate due to unpredictable traffic conditions.


5. DRILLING Drilling is a cutting process used to remove long cylinders from a rock or soil mass. It is used to gather data about the rock, provide drainage, sink a well and prepare the site for blasting if needed. The drill consists of a bit (the part actually cutting through the rock/soil) and the shank (short steel striking bar that attaches to the drill piston and transfers the blow and energy to the steel bit) The bit is very important as the efficiency of the operation depends on its ability to remain sharp during the impacts. The selection of the drilling equipment depends on the purpose of the holes, the nature of the terrain, the required depth of the holes, hardness of the rock, extent to which the rock formation is broken or fractured, the size of the project, and the availability of water for drilling purposes.

During a preliminary geotechnical investigation by Jeffery and Katauskas Pty Ltd (“20081ZAlet�), assessment of the subsurface conditions were required to recommend excavation conditions, retention, footings, basement slabs-on-grade, and soil aggression. One borehole (BH101) was auger drilled to 6.23m below the existing grade using a track mounted JK250 drill rig. This track mounted drill rig was used as these small-diameter holes were used. This was done so the relative compaction/density of the subsoil could be assessed. Groundwater observations could also be done. Deeper drilling was not possible due to the large fragments from the overlying fill collapsing into the borehole. Track mounted-drills were used for the smaller diameter and shallow blasthole as they are easy to move and position. The drilling production rate is estimated through the knowledge of the depth of the hole, penetration rate, drilling time, the time to blow hole and move to the next one, aligning the steel and changing the bit. The operating rate, production efficiency and hourly production hour will allow a more accurate rate to be estimated. Sub-drilling is necessary.


REFERENCES Alexander Fluegel, last updated December 7, 2007, 'Statistical calculation and development of glass properties, http://glassproperties.com/glasses/, accessed: Sunday23rd August' Menai Civil Contractors, ‘Barker Street Lodge Geotechnical Report.pdf’ Linx Group http://www.linxgroup.com.au/CMS-News/10-Barker-Lodge.htm


CVEN2101