Issuu on Google+

CONCRETE RECYCLED AGGREGATE: CRUSHED CONCRETE ROHIT C. BELSARE PRAJAKT KARMARKAR

A REVIEW OF RECYCLING PROCESS OF CONCRETE WITH ITS MANUFACTURING PROCESS, ULTILSATION AND TAILEND OF THE CYCLE.

Advanced Building Systems- Spring 2012 - SCI-Arc - Instructors: Jeffrey Landreth / Ilaria Mazzoleni


CONTENTS: INVESTIGATION 05 CONSTITUENTS WHY RECYCLE CONCRETE AGGREGATE? SITE VISIT I SITE VISIT II

EVALUATION 10 CONCRETE RECYCLING SUBSYSTEM LIFECYCLE OF CONCRETE PRODUCTS LIFECYCLE OF CONCRETE SITE VISIT II

OPTIMIZATION 13 OBSERVATIONS MATERIAL MANAGEMENT METHODOLIGIES LIMITATIONS OF METHODOLOGIES CONCLUSIONS SOLUTIONS

CREDITS AND BIBLOGRAPHY

16


You can tell how high a society is by how much of its garbage is recycled.� -- Dhyani Ywahoo 4


THE CONCRETE CONSITS OF THE FOLOWING COMPONENTS: CEMENT: CEMENT IS PREFERABLY PORTLAND CEMENT. CEMENT IS MADE BY HEATING LIMESTONE (CALCIUM CARBONATE) WITH SMALL QUANTITIES OF OTHER MATERIALS (SUCH AS CLAY) TO 1450 °C IN A KILN, IN A PROCESS KNOWN AS CALCINATION, WHEREBY A MOLECULE OF CARBON DIOXIDE IS LIBERATED FROM THE CALCIUM CARBONATE TO FORM CALCIUM OXIDE, OR QUICKLIME, WHICH IS THEN BLENDED WITH THE OTHER MATERIALS THAT HAVE BEEN INCLUDED IN THE MIX. THE RESULTING HARD SUBSTANCE, CALLED ‘CLINKER’, IS THEN GROUND WITH A SMALL AMOUNT OF GYPSUM INTO A POWDER TO MAKE ‘ORDINARY PORTLAND CEMENT’, THE MOST COMMONLY USED TYPE OF CEMENT (OFTEN REFERRED TO AS OPC). IT IS THE MAIN BINDING AGENT.

INVESTIGATION

CONSTITUENTS:

SAND: SAND IS USED AS A BINDING AGENT. IT IS MADE UP OF FINE GRAINS OF EARTH AND STONES. THE MOST COMMON SOURCES ARE STONE QUARRIES AND RIVER BEDS.IT HELPS IN MAKING THE CONCRETE STRONG. AGGREGATE: AGGREGATE IS THE ADDDDITIVE MATERIAL. THE MOST COMMON SOURCES ARE STONE QUARRIES AND MINES. THEY ARE NOTHING BUT CRUSHED STONE FRAGMENTS. ITS RATIO DEPENDS ON THE PURITY OF THE MIXTURE DESIRED. WATER: WATER IS USED AS A MIXING COMPONENT AND IT ALSO HELPS IN CEMICAL REACTION OF CONCRETE WHICH HELPS IN MAKING IT HARD. REINFORCEMENT: REINFORCEMENT MADE OF STEEL IS USED FOR STRUCTURAL MEMEMBER CASTING LIKE COLUMNS AND BEAMS.

WHY RECYCLE CONCRETE AGGREGATE ? • • • • • • • •

CONCRETE AGGREGATE IS HIGH QUALITY - MEETING OR EXCEEDING ALL APPLICABLE STATE AND FEDERAL SPECIFICATIONS CONCRETE AGGREGATE IS AN ACCEPTED SOURCE OF AGGREGATE INTO NEW CONCRETE BY MAJORITY OF THE NORMS. CONCRETE AGGREGATE IS CURRENTLY BEING USED IN CONCRETE AND ASPHALT PRODUCTS WITH BETTER PERFORMANCE OVER COMPARABLE VIRGIN AGGREGATES. CONCRETE AGGREGATE PROVIDES FOR SUPERIOR COMPACTION AND CONSTRUCTABILITY. CONCRETE AGGREGATE IS HIGHER YIELD - RECYCLED AGGREGATES ARE LIGHTER WEIGHT PER UNIT OF VOLUME, WHICH MEANS LESS WEIGHT PER CUBIC YARD, RESULTING IN REDUCED MATERIAL COSTS, HAUL COSTS, AND OVERALL PROJECT COSTS. CONCRETE AGGREGATE WEIGHS TEN TO FIFTEEN PERCENT (10%-15%) LESS THAN COMPARABLE VIRGIN QUARRY PRODUCTS. CONCRETE AGGREGATE OFFERS A WAY TO REDUCE LANDFILL WASTE STREAMS. CONCRETE AGGREGATE MEANS MINIMIZATION OF ENVIRONMENTAL IMPACTS IN AN URBAN QUARRY SETTING.

5


INVESTIGATION

SITE VISIT: I DOWNTOWN DIVERSION INC.

ABOUT: DOWNTOWN DIVERSION INC. ARE ONE OF THE LEADING RECYLCING SORTING COMPANIES IN LOS ANGELES,CALIFORNIA. THEY ARE LOCATED ONT HE CROSSSING OF EAST OLYMPIC AND SOUTH SANTA FE CROSSING. THEY COLLECT AND PROCESS ALL KINDS OF TRASH FROM DIFFERENT SOURCES THROUGHOUT LOS ANGELES. WHAT THEY DO: DOWNTOWN DIVERSION COLLECT THE TRASH AND SORT IT OUT BY USING DIFFERENT PROCESSESS. THEY MAINLY DEAL WITH ALL KINDS OF CONSTRUCTION AND DEMOLITION WASTE. WHAT THEY COLLECT: THEY MAINLY COLLECT THE FOLLOWING MATERIALS: METAL: ALUMINUM, STEEL, COPPER, BRASS PLASTIC: DOMESTIC AND INDUSTRIAL CONCRETE AND CONSTRUCTION WASTE WOOD AND WOODEN PRODUCTS. WHAT IS THE PROCESS: DOWNTOWN DIVERSION IC. COLLECT THE WASTE THEY MEASURE IT BY WIEGHT AND THEY BUY THESE WASTES EITHER BY THEMSLEVES OR JUST SORT OUT THE WASTE ACCORDING TO THE MATERIALS FOR THE CLIENT. THEY USE DIFFERENT PROCESSES LIKE: A) MANUAL SORTING ALONG A CONVEYOR BELT FOR WOOD AND CONCRETE WASTE. B) MAGNETIC SORTING FOR STEEL AND IRON BASED WASTES. C) CHEMICAL SORTING FOR PLASITCS. D) INCENARATION FOR FLAMABLE MATERIALS. TAILEND OF THE PROCESS: THE TAILEND OF THE PROCESS LIES IN THE SEGGREGATION OF THESE MATERIALS AND SORTING THEM ACCORDINGLY. THE MOST COMMON RESULTS OF THE SORTING PROCESS ARE AS FOLLOWS: A) PLASTICS ARE SENT FOR RECYCLING TO RECYCLING PLANTS AND EXPORTED TO COUNTRIES LIKE CHINA. B) WOODEN COMPONENTS ARE EITHER BURNT OR CONVERTED INTO SAWDUST FOR MAKING OF ITEMS LIKE PAPER, CHIPBOARDETC. C)CONCRETE WASTE IS SORTED OUT OF THE DEMOLITION WASTE AND CLEANED OUT OF SUBSTANCES LIKE METAL AND PLASTIC PARTS AND IS SEND TO CONCRETE AGGREGATE RECYCLING PLANTS LIKE 25TH STREET RECLYCLING INC.

6


25TH STREET RECYCLING INC.

INVESTIGATION

SITE VISIT: II

ABOUT: 25TH STREET RECYCLING INC. IS A RECYCLING COMPANY WHICH DEALS MAINLY WITH RECYCLING OF COCNRETE AGGREGATE. THEY ARE A SUBSIDARY OF SECURITY PAVING CO. WHICH IS A PAVING TILING MANUFACURING COMPANY AND A ROAD CONSTRUCTION COMPANY. WHAT THEY DO: 25TH STREET RECYCLING INC. COLLECTS CONSTRCUTION AGGREGATE WASTE FROM DIFFERENT VENDORS LIKE DOWNTOWN DIVERSION AND PRIVATE WASTE COLLECTORS, WEIGHS THEM AND SORTS AND CRUSHES IT INTO FINE AGGREGATE FOR RECYCLING COMMONLY KNOWN AS ‘BASE’ .

WEIGH BRIDGE FOR CONCRETE WEIGHING AND COLLECTION

7


INVESTIGATION

WHAT THEY COLLECT: CONCRETE AND ASPHALT AGGREGATE.

CONCRETE AGGREGATE WASTE ON SITE. WHAT IS THE PROCESS: THEY COLLECT THE WASTE FROM VARIOUS SOURCES WHICH IS PREFERABLY SORTED AND CLEANDED OF METAL AND OTHER IMPURITITES.THEN THEY SORT OF THE WASTE AND CLEAN IT IF NOT CLEANED. THEY WEIGH IT AND BUY THE WASTE FOR THE PARENT COMPANY OR PROCES IT FOR OTHER VENDORS. THIS WASTE COLLECTED IS CRUSHED INTO FINE GRANULES CALLED AS BASE BY A STONE CRUSHER. THIS IS THEN SOLD OFF TO DIFFERENT SOURCES AT A PRICE OF AROUND 5$ PER TON. TAILEND OF THE PROCESS: THE CRUSHED BASE IS EITHER USED FOR MANUFACTURING OF FREEWAY DIVIDER BEAMS, PAVING AND OTHER ROAD LANDSCAPING PRODUCTS. THE CRUSHED BASE IS ALSO USED FOR AS FILL IN ROAD CONSTRUCTION OR FOUNDATION CONSTRUCTION OR IS USED AS LANDFILL.

SITE PHOTOGRAPH

8


INVESTIGATION STONE CRUSHER

STEEL WASTE

FREEWAY COMPONENTS FROM BASE CRUSHING OF AGGREGATE INTO BASE BY USING STONE CRUSHER INTERVIEW WITH MR. CARLOS, SITE MANAGER: Q: FROM WHERE DO YOU COLLECT WASTE? A: FROM PRIVATE COLLECTORS AND C & D WASTE MANAGEMENT PROGRAMS. ARE CHARGED ONLY FOR THE PROCESSING. Q: HOW DO YOU SORT OUT CONCRETE WASTE FROM OTHER WASTE LIKE STEEL AND METALS? A: WE DO IT EITHER BY MANUAL SEPERATION OR BY MAGNETIC SEPERATION MACHINES. Q: WHAT DO YOU DO OF THE CRUSHED WASTE? A: WE SELL IT TO OTHER VENDORS AS BASE OR USE IN OUR OWN PRODUCTS. Q: WHAT IS THE SELLING PRICE OF BASE? A: IT IS AROUND 5 TO 6 DOLLARS PER TONNE. Q: WHY IS NOT THE BASE USED IN REGULAR CONSTRUCTION? A: IT HAS CONTAMINATION LIKE LEAD AND PAINT CONTAMINATION WHICH MAKE THE NEW MIXTURE WEAK IN STRENGTH AND UNFIT FOR REUSE. Q: THEN WHERE IS THE BASE USED? A: IT IS USED IN OUR OWN PRODUCTS LIKE FREEWAY DIVIDER BEAMS OR ROAD CONSTRUCTION OR IN LANDFILLS.

9


EVALUATION

CONCRETE RECYCLING SUBSYSTEM THE FOLLOWING IS THE SUBSYSTEM OBSERVED THROUGHOUT THE TWO SITE VISITS

New Construction

Renovation

Resource Material

Demolition

LA City waste

Individual Vendors

Resources of Energy ( Transportation and Process)

Raw Material to Parent Industry Downtown Diversion Inc. (Sorting and seperation)

Other Co-Products (Steel)

Wastes

25th Street Recycling Inc.

10

Emissions (To Air, Water and Soil)


EVALUATION

LIFE CYCLE OF CONCRETE PRODUCTS:

11


EVALUATION

12

LIFE CYCLE CONCRETE:


FOLLOWING ARE THE OBSERVATIONS DURING THE WHOLE PROCESS: • THERE IS A WHOLESOME UTILIZATION OF ENERGY WHEN COMPONENTS OF CONCRETE LIKE CEMENT ARE PRODUCED. • PRODUCTION OF CEMENT ITSELF EMITS A LOT OF HARMFUL EFFLUENTS DISTURBING AND DAMAGING THE ENVIRONMENT. • THE PREPERATION OF CONCRETE IS ALSO A VERY ENERGY CONSUMING PROCESS. MIXING OF CONCRETE REQUIRES DEPENDIBLITY ON RESOURCES LIKE FOSSIL FUELS, ELECTRICITY AND MANPOWER. • OTHER NATURAL RESOURCES LIKE WATER, STONE AND EARTH ALSO CONSUMED WHILE MANUFACTURING CONCRETE. • IN THE RECYCLING OF CONCRETE, A LOT OF ENERGY IS NEEDED. • THERE IS A LOT OF ENERGY AND RESOURCES UTILIZATION IN THE PROCESS OF EXTRACTION AND SEPERATION OF THESE WASTES AS PER DIFFERENT MATERIALS.

OPTIMIZATION

OBSERVATIONS:

MATERIALS MANAGEMENT METHODOLOGIES SOURCE REDUCTION: WHEN A MATERIAL IS SOURCE REDUCED (I.E. LESS OF MATERIALS IS MADE), THE EMISSIONS ASSOCIATED WITH MAKING OF THE MATERIAL AND MANAGING HTE POSTCONSUMER WASTE ARE AVOIDED. ALTHOUGH CONCRETE MAY BE USED OR REUSED IN WAYS THAT COULD REDUCE THE OVERALL DEMAND FOR NEW CONCRETE STRUCTUTRES, THE BENIFITS OF THIS TYPE OF ACITIVITY HACE NOT YET BEEN QUANTIFIED. RECYCLING: WHEN A MATERIAL IS RECYCLED, IT IS USED IN PLACE OF VIRGIN MATERIALS AND INPUTS IN THE MANUFACTURING RATHER THAN BEING DISPOSED OUT AS WASTE .THE CONSTRCUTION MATERIALS RECYCLING ASSOCIATION OF AMERICA (CMRA,2010) INDICATES THAT APPROXIMATELY 140 MILLION TONNES OF CONRETE ARE RECYCLED AND REUSED INT HE UNITED STATES. WHEN THE STRUCTURES ARE DEMOLISHED, THE WASTES CAN BE CRUSHED AND REUSED FOR VARIETY OF APPLICATIONS LIKE ROAD BASE, LANDFILL AND AS INGRADIENT IN CONCRETE AND ASPHALT PAVEMENT. COMPOSTING: CONCRETE CANNOT BE SUBJECTED TO AEROBIC BACTERIAL DEGRADATION AND HENCE CANNOT BE COMPOSTED. COMBUSTION: CONCRETE CANNOT BE COMBUSTED. LANDFILLING: IN GENERAL, EMISSIONS FROM LANDFILLING CONSIST OF LANDFILL CH4; CO2 EMISSIONS FROM TRANSPORTATION AND LANDFILL EQUIPMENT OPERATION; LANDFILL CARBON STORAGE; AND AVOIDED UTILITY EMISSIONS THAT ARE OFFSET BY LANDFILL GAS ENERGY RECOVERY. HOWEVER, SINCE CONCRETE IS NOT SUBJECT TO AEROBIC BACTERIAL DEGRADATION AND DOES NOT DEGRADE IN LANDFILLS, IT DOES NOT PRODUCE ANY CH4 EMISSIONS ASSOCIATED WITH LANDFILLING CONCRETE. STUDIES HAVE INDICATED THAT, OVER TIME, THE CEMENT PORTION OF CONCRETE IS CAPABLE OF ABSORBING CO2 (GADJA, 2001). THE AMOUNT OF CARBON STORED IS AFFECTED BY AGE, CEMENT CONTENT AND THE AMOUNT OF EXPOSED SURFACE AREA. WHILE THIS EFFECT WOULD REPRESENT LANDFILL CARBON STORAGE WHEN CONCRETE IS DEPOSITED IN A LANDFILL, THE RESULTS OF THIS WITH RESPECT TO THE EMISSION FACTOR ARE DIFFICULT TO QUANTIFY AND ARE CONSIDERED TO BE BEYOND SCOPE. THEREFORE, ONLY THAT COUNTS IS THE TRANSPORTATION EMISSIONS: TRANSPORTATION OF CONCRETE TO A LANDFILL AND OPERATION OF LANDFILL EQUIPMENT RESULT IN ANTHROPOGENIC CO2 EMISSIONS DUE TO THE COMBUSTION OF FOSSIL FUELS IN THE VEHICLES USED TO HAUL AND MOVE THE WASTES.

13


OPTIMIZATION

LIMITATIONS OF METHODOLOGIES: ALTHOUGH THIS ANALYSIS IS BASED UPON THE BEST AVAILABLE LIFE‐CYCLE DATA, UNCERTAINTIES DO EXIST IN THE FINAL EMISSION FACTORS. THIS LIFE CYCLE ASSESSMENT HAS THE FOLLOWING LIMITATIONS: •

LANDFILL CARBON STORAGE BY THE CEMENT COMPONENT OF CONCRETE DEPOSITED IN A LANDFILL IS DIFFICULT TO QUANTIFY AND CONSIDERED TO BE BEYOND THE SCOPE OF WARM. BETTER DATA AND MORE INFORMATION ON THIS STORAGE PROCESS WOULD HELP ENHANCE THE LANDFILL EMISSION FACTOR. THERE IS A CURRENT LACK OF SUFFICIENT DATA TO QUANTIFY THE GHG BENEFITS OF “CLOSED‐LOOP” RECYCLING OF CONCRETE. CONCRETE MAY BE RECYCLED AND REUSED AS AGGREGATE IN NEW CONCRETE SUCH THAT IT REHYDRATES SOME CEMENT IN THE USED CONCRETE, THUS REDUCING THE NEED FOR CEMENT IN THE NEW CONCRETE, AND RESULTING IN ADDITIONAL BENEFITS. MORE INFORMATION RELATED TO A DECREASE IN NEED FOR VIRGIN CEMENT DUE TO THIS KIND OF RECYCLING WOULD HELP IMPROVE THE RECYCLING EMISSION FACTOR. IF UPDATED INFORMATION COULD BE OBTAINED TO ADDRESS THESE LIMITATIONS, THE LIFE‐CYCLE EMISSION FACTOR FOR CONCRETE COULD BE FURTHER REFINED. IT IS IMPORTANT THAT WE CONTINUE TO ASSESS THE ASSUMPTIONS AND DATA USED TO DEVELOP THE EMISSION FACTORS. AS THE COMBUSTION PROCESSES, MANUFACTURING PROCESSES AND RECYCLING PROCESSES CHANGE IN THE FUTURE, THESE CHANGES WILL BE INCORPORATED INTO REVISED EMISSION FACTORS. IN ADDITION, IT SHOULD BE NOTED THAT THESE RESULTS ARE DESIGNED TO REPRESENT NATIONAL AVERAGE DATA. THE ACTUAL IMPACTS OF RECYCLING OR LANDFILLING CONCRETE WILL VARY, DEPENDING ON INDIVIDUAL CIRCUMSTANCES.

CONCLUSIONS: A)ENVIRONMENT: 1) THE PROCESSES OF QUARRYING, CRUSHING, AND GRINDING OF NATURAL AGGREGATES PRODUCES A GREATER ENVIRONMENTAL BURDEN THAN THE PROCESSES OF CRUSHING AND RECYCLING OF CONCRETE, ESPECIALLY CONCERNING CO2. THIS IS PROBABLY DUE TO THE FACT THAT, IN ALL PROCESSES OF PRODUCING NATURAL AGGREGATES, THE EXTRACTION PROCESSES MUST ALSO BE CONSIDERED, WITH THE CONSUMPTION OF ENERGY IMPLICIT IN THESE. THE AMOUNT OF CO2 EMITTED IS APPROXIMATELY 3,000 G PER TON OF RECYCLED AGGREGATE, WHILE THIS VALUE VARIED FROM AROUND 6,900 TO 7,700 G PER TON FOR THE GRAVEL AND SAND EXTRACTION PROCESSES CONSIDERED. 2)THE MAJOR PART OF THE ENVIRONMENTAL BURDENS PRODUCED IN THE DIFFERENT SYSTEMS IS THE RESULT OF TRANSPORT. THESE PROCESSES ARE RESPONSIBLE FOR THE MOST ENERGY USAGE AND EMISSIONS OF GASES AND PARTICULATES. 3) THE IMPORTANCE OF REDUCING THE CONSUMPTION OF FOSSIL ENERGY IS EMPHASIZED IN ORDER TO REDUCE POTENTIAL IMPACTS ON THE ENVIRONMENT.

CARBON FOOTPRINT

WATER FOOTPRINT

ECOSYSTEMS QUALITY

NATURAL RESOURCES

HUMAN HEALTH

14


B) APPLICATIONS

CREDITS

CONCLUSIONS: IN GENERAL, APPLICATIONS WITHOUT ANY PROCESSING INCLUDE: 1) MANY TYPES OF GENERAL BULK FILLS 2) BANK PROTECTION 3) BASE OR FILL FOR DRAINAGE STRUCTURES 4) ROAD CONSTRUCTION 5) NOISE BARRIERS AND EMBANKMENTS AFTER REMOVAL OF CONTAMINANTS THROUGH SELECTIVE DEMOLITION, SCREENING, AND /OR AIR SEPARATION AND SIZE REDUCTION IN A CRUSHER TO AGGREGATE SIZES, CRUSHED CONCRETE CAN BE USED AS: 1) NEW CONCRETE FOR PAVEMENTS, SHOULDERS, MEDIAN BARRIERS, SIDEWALKS, CURBS AND GUTTERS, AND BRIDGE FOUNDATIONS 2) STRUCTURAL GRADE CONCRETE 3) SOIL-CEMENT PAVEMENT BASES 4) LEAN-CONCRETE 5) BITUMINOUS CONCRETE C) SUSTAINABILITY 1) RECYCLING THE CONCRETE REDUCES THE AMOUNT OF MATERIAL THAT MUST BE LANDFILLED. 2) RECYCLED CONCRETE AGGREGATES REDUCES THE NEED FOR VIRGIN AGGREGATES. 3) RECYCLED CONCRETE AGGREGATES ABSORB A LARGE AMOUNT OF CARBON DIOXIDE FROM THE SURROUNDING ENVIRONMENT. THE NATURAL PROCESS OF CARBONATION OCCURS IN ALL CONCRETE FROM THE SURFACE INWARD. IN THE PROCESS OF CRUSHING CONCRETE TO CREATE RECYCLED CONCRETE AGGREGATES, AREAS OF THE CONCRETE THAT HAVE NOT CARBONATED ARE EXPOSED TO ATMOSPHERIC CARBON DIOXIDE.

SOLUTIONS: THE FOLLOWING COULD BE SOLUTIONS: • • • • • •

USING OF MODULAR CONSTRUCTION. SUBSTITUTION OF BIO-DEGRADABLE SUBSTANCES FOR REGULAR SUBSTANCES IN CONCRETE MAKING PROCEDURE. SUBSTITUTION OF MATERIALS WHICH REQUIRE LESS ENERGY IN THE PROCESS OF PRODUCTION AND MANUFACTURING. USAGE OF SUSTAINABLE MATERIALS AND MATERIALS FROM NATURAL AND RENEWABLE SOURCES. IMPLEMENTATION OF DESIGN TECHNIQUES TO DECREASE THE TOTAL MATERIAL VOLUME USED PER STRUCTURE. USING OF SUBSTANCES LIKE FLY-ASH IN STRUCTURAL CONSTRUCTION.

15


OPTIMIZATION

CREDITS AND BIBLOGRAPHY www.concreterecycling.org www.wikipedia.org http://www.epa.gov/climatechange/wycd/waste/downloads/ClayBrickandConcrete_11_07.pdf

16



Concrete Aggregate Recycling