Precast Concrete Panels

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Efficient Building Materials

PRECAST CONCRETE PANELS

Life Cycle Assessment

ANIKET CHAUDHARI Semester 11 Rachana Sansad’s Institute of Environmental Architecture YCMOU

CONTENTS SR NO. DESCRIPTION

Acknowledgements 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. INTRODUCTION TO PRECAST CONCRETE PANELS INTRODUCTION TO CHOSEN BRAND RAW MATERIALS SOURCE OF THE RAW MATERIALS PROCESS OF MANUFACTURING ENERGY CONSUMPTION IN PROCESS AND TRANSPORTATION LABOURS APPLICATIONS COST ENVIRONMENTAL IMPACT OF THE MATERIAL BIBLIOGRAPHY

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ACKNOWLEDGEMENT This assignment would not have been possible without the help of my guides Prof. Roshni Udyavar, Prof. Ashok Joshi. I would also like to thank Mr. G. SEKHAR SINGH, Managing Director of ECOMATTE, Chennai, for helping with the collection of data.

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INTRODUCTION

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Precast Concrete Panels: A precast concrete panel is: A panel, tile, counter, Fin, wall etc that is usually poured in a controlled manufacturing facility (although it can be poured on site) into a mold of a specific shape. Whether it is mass produced or a custom shape the precast panel is usually finished (sealed) before installation (although, again this also can be done on site). There are 2 ways to install concrete products: Pour on site or precast and install. There are many pros and cons for each process. Which method to use depends on what the customer/architect/designer/engineer is trying to accomplish. Precast concrete is a form of construction, where concrete is cast in a reusable mould or "form" which is then cured in a controlled environment, transported to the construction site and lifted into place. No construction material or product can guarantee LEED Certification of our project. Precast concrete panels can help reach as many as 23 of the 26 points needed to achieve LEED certification. This translates directly into both economic and environmental savings. Using less material means using fewer natural resources and less manufacturing and transportation energy. Precast concrete components can help achieve LEED certification in a variety of ways: • • • Their ability to be recycled Local manufacturing capability Thermal mass

• Sandwich insulation

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BRAND INTRODUCTION

ECO-MATTE CONCRETE PANELS:

• •

They are the pioneers in manufacturing environmental friendly and lightweight building materials. They are not only contributing Environmental friendly building products to build a greener world, but also leaders in introducing the latest state of the art building materials and import substitutions.

ECO FRIENDLY PRODUCT: • Raw Material contains more than 70% of recycled power plant waste (Fly-Ash) • • • • • Manufacturing process is 100% recyclable-cut/use. 0% emission of Co2 Uses one third raw material from mother earth, due to low density and very low impact Good Thermal Insulation-Lower energy cost (up-to 26% power savings) Good Sound insulation– Low noise

Mainstay’s of building construction is steadily giving way to new vastly building concepts in India. Hi-Conk building slabs eco-friendly and are ideal for modern day buildings, assuring quality construction and quality living. Hi-conk building slabs have attracted leading builders Everywhere because of the many advantages they offer.

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Light Weight:
• 1/3rd the density of normal Slabs • Economic design saving in cement and steel • Enables faster construction • Suitable for low-bearing capacity and seismic zones

Fire Resistance:
• Hi-Conk Blocks are classified non combustible • High temperature barrier • No toxic fumes in case of fire • Hi-Conk building blocks are appropriate for fire-rated applications for desired safety

Easy workability:
• Hi-Conk building slabs are easy to fix.

Earth-Quake resistance:
Hi-Conk Blocks are earth quake resistance due to • Light weight-Low Inertia Forces • Tongue & Groove-Local adjustment during shaking • Flexible Jointing Material-Flexibility and shock absorbing characteristics • Top and Bottom channels-Partial Base Isolation • Strengths-Adequate to take tension, compression Flexural & shear forces. • Ductility-Roof and wall panels connected by steel components.

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High Thermal Insulation:
• Low thermal conductivity • Thermal performance 5 times better than concrete slabs . • Savings in recurring cost in air-conditioning • Ideal material for applications in cold storage room • Interiors remain cool in summer

Good Sound Insulation:
• Possess excellent sound reduction capacity • Fulfills required Sound transmission class (STC) • Up to 37-42 db sound reduction based on thickness • CLC inherent sound insulating properties make it ideal for controlling noise transmission between adjoining rooms • Higher sound insulation to be obtained based on the need by giving higher density blocks for special applications . • Reduces echo effect in an empty room.

Reduction in Cost:
• Enormous savings of time and manpower. • Substantial savings in cement and steel consumption • More carpet area and Minimal wastages • Much Cheaper than any other building blocks available in the market

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MAP OF INDIA SHOWING MANUFACTURING OF PRECAST CONCRTE PANELS PLANTS:

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RAW MATERIALS

PORTLAND CEMENT: Portland cement is made from four basic compounds, tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A), and tetracalcium aluminoferrite (C4AF). Portland cement is made by heating common minerals, primarily crushed limestone, clay, iron ore, and sand, to a white-hot mixture to form clinker. Carbon dioxide emissions from a cement plant are divided into two source categories: combustion and calcination. Combustion accounts for approximately 35% and calcination 65% of the total CO2 emissions from a cement manufacturing facility. The combustion-generated CO2 emissions are related to fuel use. The calcination CO2 emissions are formed when the raw material is heated and CO2 is liberated from the calcium carbonate. When concrete is exposed to the air and carbonates, it reabsorbs some of the CO2 released during calcination. Calcination is a necessary key to cement production; the focus of reductions in CO2 emissions during cement manufacturing is on reducing fuel and energy use. FLY ASH: Fly ash is a pozzolan waste product collected from coal-fired power plants. Fly ash contains some heavy metal (normally more than silica fume), so the heavy metal content of the concrete will increase.

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Fly ash refines the pore structure of the concrete, making it more resistant to chloride penetration. Not all fly ash is suitable for use in concrete mixtures. their use as a replacement for portland cement does not contribute to the energy and CO2 effects of cement in concrete. SILICA FUME: Silica fume is a waste product recovered from the reduction of highpurity quartz with coal in electric furnaces in the production of silicon and ferrosilicon alloys. Silica fume improves the quality, strength and durability of concrete by making the concrete much less permeable and more resistant to corrosion of the steel reinforcement SLAG CEMENT: In the blast furnace, magnetic iron ore (Fe3O4) and haematic iron ore (Fe2O3) are fed along with limestone into a high temperature chamber containing coke. Coke is partially oxidized to carbon monoxide, which reduces the ores to iron. The other product that floats over the molten iron due to its relative lightness is called slag. Slag is composed of calcium oxide (CaO), silica (SiO2) and alumina (Al203). Slag is pulverized into a fine powder called ground granulated blast furnace slag and is used in this form as a cementitious component of concrete.

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When slag cement replaces 50% of the portland cement in 50 MPa concrete, greenhouse gas emissions per cubic yard of concrete are reduced by 45%. Because the cementitious content of concrete is about 15%, these pozzolans typically account for only 2% to 5% of the overall concrete material in buildings.

SOURCES OF MATERIALS: Natural gravel and sand are usually dug from a pit, river, lake, or seabed. Crushed aggregate is produced by crushing quarry rock, boulders, cobbles, or large-size gravel. Recycled concrete is a viable source of aggregate and has been satisfactorily used in granular sub bases, soil-cement, and in new concrete Main characteristics that are considered when selecting aggregate include: • Grading • Durability • Particle shape and surface texture • Abrasion and skid resistance • Unit weights and voids • Absorption and surface moisture

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PROCESS OF MANUFACTURING: FLOW CHART SHOWING THE PROCESS OF MANUFACTURING:

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MANUFACTURING OF THE PRECAST CONCRETE PANELS: The manufacture of the components can be done in a factory for the commercial production or in a site precasting yard set up at or near the site of work. • • Factory prefabrication Site prefabrication

Semi-mechanized : The work is normally carried out in open space with locally available labor force. Fully-mechanized : The work will be carried out under shed with skilled labor. Set up for high quality, high rate of production. The various processes involved in the manufacture of precast panels may be classified as follows: Main process: 1) Providing and assembling the moulds, placing reinforcements cage in position for reinforced concrete work. 2) Fixing of inserts and tubes, where necessary. 3) Pouring the concrete into the moulds. 4) Vibrating the concrete and finishing. 5) Curing. 6) Demoulding the forms and stacking the precast products. Auxiliary process: Process necessary for the successful completion of the processes covered by the main process:

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1) Mixing and manufacture of fresh concrete 2) Prefabrication of reinforcement cage (done in steel yard or workshop) 3) Manufacture of inserts and other finishing items to be incorporated in the main precast products 4) Finishing the precast products 5) Testing of products Subsidiary process: All other work involved in keeping the main production work to a cyclic working: 1) Storage of materials 2) Transport of cement and aggregates 3) Transport of concrete and reinforcement cages 4) Transport and stacking the precast elements 5) Generation of steam

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STAGES OF PRECASTING OF ECO-MATTE CONCRETE PANELS: STAGE 1: Procurement and storage of construction materials Unloading and transport of cement, coarse and the aggregates, and steel, and storing them in bins, silos or storage sheds. STAGE 2: Testing of raw materials Testing of raw materials including steel STAGE 3: Design of concrete mix Testing of raw materials, plotting of grading curves and trial of mixes in the laboratory STAGE 4: Making of reinforcement cages Uploading of reinforcement bars from wagons or lorries and stacking them in the steel yard, cutting, bending, tying or welding the reinforcement and making in the form of a cage, which can be directly introduced into the mould. STAGE 5: Applying form release agent and laying of moulds in position Moulds are cleaned, applied with form release agent and assembled and placed at the right place. STAGE 6: Placing of reinforcement cages, inserts and fixtures The reinforcement cages are placed in the moulds with spacers, etc as per data sheet prepared for the particular prefabricate. STAGE 7: Preparation of green concrete Taking out aggregates and cement from bins, silos. Batching and mixing.

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STAGE 8: Transport of green concrete Transport of green concrete from the mixer to the moulds, In the case of precast method involving direct transfer of concrete from mixer to the mould or a concrete hopper attached to the mould this prefabrication stage is not necessary. STAGE 9: Pouring and consolidation of concrete Concrete is poured and vibrated to a good finish. STAGE 10: Curing of concrete and demoulding Either a natural curing with water or an accelerated curing using steam curing and other techniques. In the case of steam curing using trenches or autoclaves, this stage involves transport of moulds with the green concrete into the trench and taking them out after the curing and demoulding elements cutting of protruding wires also falls in this stage. In certain cases the moulds have to be partly removed and inserts, have to be removed after initial set. The total demoulding is done after a certain period and the components are then allowed to be cured. All these fall in this operation. STAGE 11: Stacking of precast panels Lifting of precast panels from the mould and transporting to the stacking yard for further transport by trailer or rail is part of this stage STAGE 12: Testing of finished components Tests are carried out on the components individually and in combination to insure the adequacy of their strength.

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FACTORY PROCESS:

MAKING OF FORMS

PLACING REINFORCEMENT CAGES

POURING OF CONCRETE

CURING PROCESS

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ENERGY CONSUMPTION IN THE PROCESS AND TRANSPORTATION: In the manufacturing process of precast concrete the major electricity and fuel energy consuming process are: • Machineries required for quarrying of coarse and fine aggregates; • Conveying equipment, such as, belt conveyors, chain conveyors, screw conveyors, bucket elevators etc.; • Concrete mixing machines ; • Concrete vibrating machines; • Erection equipments, such as, tractor-cum-trailers, dumpers, lorries, locomotives, motor boat and rarely even helicopters; • Workshop machinery for making and repairing steel and timber moulds; • Bar straightening, bending and welding machines to make reinforcement cages; • Minor tools and tackles, such as, wheel barrows, concrete buckets etc;

• Steam generation plant for accelerated curing. • If we take transportation, when a building uses precast elements, large parts of the building can be brought to the site with each transport. Larger trucks consume less fuel per ton transported. Precast concrete structures are usually lighter than the equivalent area of on-site-cast-in-place concrete this can represent significant reduction in the number of truck movements and reduced consumption of fossil fuels. The amount of energy consumed during transport of precast element is about 0.00114MJ/kg/km.

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This represents 5%to 10% of the total energy consumption during manufacturing of precast concrete panels WATER FINE AGGREGATES COARSE AGGREGATES CEMENT CHENNAI 145 KMS CHENNAI 230 KMS MILD STEEL NEAR CHENNAI 550 KMS

CHENNAI CHENNAI 125 KMS PRIMARY ENERGY 750 KGS 7230 MJ TRANSPORTATION ENERGY 125 KMS 356.25 MJ TOTAL 7586.25 MJ

750 KGS 7230 MJ

800 KGS 7712 MJ

185 KGS 1783.4 MJ

145 KMS 413.25 MJ

230 KMS 655.5 MJ

550 KMS 1567.5 MJ

7643.25 MJ

8367.5 MJ

3350.9 MJ

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LABOUR: Fully mechanized system is used in the production of the Ecomatte concrete panels. As compared to the semi mechanized process This will save the man power. All the work is done by skilled labors and self operating machines under shed. Very few 8-10 people will require in the entire process of production of precast concrete panels.

APPLICATION: Eco-matte concrete panels are used in varieties of industries now a days because people understood the importance of time, money and environmental impact as well as impact of materials on the human body, so it is used in large scale in: Residential building Commercial development Road development Hospitals Hotels Fast track projects MHADA buildings and many more. COST:

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APPLICATION AND INSTALLATION OF PRECAST PANELS:

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ENVIRONMENTAL IMPACT OF THE MATERIAL: While considering the environmental impact of the material from extraction, manufacturing and up to final installation we should consider it in following context: Environmental resources Environmental energy Environmental protection Some of the aspects while considering environmental impacts in the production and manufacturing of precast concrete panels. • Land-use and exploitation of natural resources (excavations, quarrying, ground water, lime stone). Mainly connected with the production of concrete constituents. • Waste products from concrete production (washing/mixing water, cement slurry, form oil, rejected concrete) • Emissions and energy consumption(CO2, SO2, embodied energy throughout production, transport and construction) • Working environment (noise, vibrations, dust, accidents...) ENVOIRNMENTAL IMPACTS AND SUSTAINABLE ADVANTAGES:  All the materials that go into precast concrete products come from natural and recycled sources, mainly inorganic. This means they are subject to minimal processing or chemical treatments to render them suitable for use, which results in concrete having a relatively low embodied energy value, unlike highly processed materials, such as plastics.

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It is estimated that shipping can double the carbon footprint of construction materials, so the associated environmental impact from shipping’s fuel consumption and pollution is clearly cause for concern Precast concrete products consist predominantly of natural aggregates – sand, coarse and fine stones from rock quarries or river gravels, so there is no real need to import these from elsewhere. The local availability of aggregates makes for low carbon footprint deliveries to the precast factory. Making cement in a kiln requires a great deal of heat energy, but the amount of non-renewable fossil fuels used to produce this heat is being reduced. Although water is a widely available resource and is currently in plentiful supply, it is important to manage its consumption. Water recycling and conservation is a common feature in precast factories. In many cases precast products incorporate materials such as blast furnace slag (GGBS) from the steel industry and fuel ash (PFA) from coal-fired power stations that might otherwise go to waste. Precast is produced in factories under strictly controlled conditions which means excellent resource efficiency for materials, labor, energy and processes. The local supply network for precast means travel distances are shorter and so the fuel used during haulage is minimized. With calls for travel distances from supplier to site to be reduced, precast is a viable and sensible option to reduce the carbon footprint of a project. Over 60 years, a concrete and masonry home emits up to 15 tons less CO2 than a lightweight alternative, so providing a better solution.



 











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The highly effective recycling systems used in precast factories enable virtually all process water, slurry, aggregates or cement to be safely re-captured and put back into production. This means that a closed-loop system is in operation – one which minimizes any outgoing waste materials. The energy associated with construction typically accounts for just 10% of a building’s energy use over its lifetime (or carbon footprint), so emphasis is more often placed on operational energy consumed, but it is also important to reduce embodied energy where appropriate. Both are possible with precast. During its lifetime precast concrete will effectively re-absorb much of the carbon dioxide that was used to create it in the first place. Precast units, aggregate blocks and aircrete will ultimately re-absorb the CO2 used to create them, a process called carbonation that accelerates when products are crushed for recycling at end of life. On a large scale, precast concrete is used to construct the towers for wind turbines, but even on a domestic scale precast products support the drive to use renewable technologies. Precast concrete and masonry products offer better protection against possible effects of climate change because they are robust, durable and have structural integrity In its daily use, precast concrete is an inert substance, so it doesn’t emit or give off any gases, toxic compounds or volatile organic compounds. This all means allergy sufferers can breathe easy because precast does not contribute to the symptoms of ‘sick building syndrome’ Because precast can be moulded to any shape, size and texture it can be used to deflect or absorb noise. This makes it a good acoustic













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host for music but also an effective sound barrier alongside busy roads.  Just like many other concrete and masonry materials, precast concrete does not melt in high temperatures. This means that there is no need for protective paints or special insulation Using an ingenious materials innovation, precast concrete incorporating titanium modified cement can reduce emissions from traffic fumes. These fumes are harmful to health and can trigger respiratory problems such as asthma. A process called photocatalysis occurs which entraps the SOx and NOx particles from vehicle exhausts. These, are then dispersed harmlessly when rain falls on the road surface. Today’s precast factories are clean, efficient and many use computer-controlled processes for batching, mixing and casting. Working in a factory means excellent resource efficiency





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BIBLIOGRAPHY 1. 2. 3. 4. 5. 6. 7. 8. INFORMATION FROM ECO-MATTE CATALOGUE CPCI_Precast_Concrete_LEED_08 Sustainable Precast http://www.ap.cc.basf.com/en/aboutus/Pages/default.aspx Total Precast Concrete Structures - CPCI - Canadian Precast Prestressed Concrete Institute www_cp NATIONAL BUILDING CODE OF INDIA 2005 Energy Conservation 64- Page www.toolbase.org/pdf/techinv/precastconcretepanels_techsp ec.pdf www.acp-concrete.co.uk

9. 10. http://www.4specs.com/s/03/03-4500.html

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