USE OF RECYCLED AGGREGATE IN CONCRETE CONSTRUCTION: A NEED FOR SUSTAINABLE ENVIRONMENT

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1 USE OF RECYCLED AGGREGATE IN CONCRETE CONSTRUCTION: A NEED FOR SUSTAINABLE ENVIRONMENT Y P Gupta*, Chairman, ICI UP Allahabad Centre Technical Advisor, New Yamuna Bridge Information Centre Professor (Rtd.) Civil Engineering, MNNIT, Allahabad, India 34 th Conference on OUR WORLD IN CONCRETE & STRUCTURES: August 2009, Singapore Article Online Id: The online version of this article can be found at: This article is brought to you with the support of Singapore Concrete Institute All Rights reserved for CI Premier PTE LTD You are not Allowed to re distribute or re sale the article in any format without written approval of CI Premier PTE LTD Visit Our Website for more information

2 34 th Conference on OUR WORLD IN CONCRETE & STRUCTURES: August 2009, Singapore USE OF RECYCLED AGGREGATE IN CONCRETE CONSTRUCTION: A NEED FOR SUSTAINABLE ENVIRONMENT Y P Gupta*, Chairman, ICI UP Allahabad Centre Technical Advisor, New Yamuna Bridge Information Centre Professor (Rtd.) Civil Engineering, MNNIT, Allahabad, India Abstract In INDIA and world over, huge amount of demolished waste is generated by construction Industry which is not put to re-use, except it is disposed off it as land fill for low lying areas. Dumping of wastes on land is not only causing shortage of space, but also environmental problems near cities. Further, due to urbanization growth, distance between demolition waste generation area and disposal land area has also become longer and therefore, transportation cost for disposal has increased and thus the excessive use of energy. Recycling of demolished waste can offer not only the solution of growing waste disposal problem, but will also help to conserve natural resources for meeting increasing demand of aggregates for long time to come for construction industry and give sustainable environment. This paper describes the outcome of tests carried out about the use of Recycled in Construction. A process to get aggregate from demolition waste is developed and its basic properties are determined. These properties are compared with conventional and local aggregate. Such recycled aggregate is tried to produce concrete of grades equivalent to M25 or similar other uses. It is found that Recycled from demolition Waste can be gainfully used in making fresh Concrete for general construction purposes, Concrete Blocks / Bricks and for rigid pavements in under layers like DLC etc. The most useful item is making Conventional Bricks similar to burnt clay bricks. INTRODUCTION For sustainable environment, development of green and environment friendly infrastructure is necessary. It is also necessary for the better growth of any Country s Economy. In India, the industrial growth is reaching nearing 9% of GDP. Therefore, rapid development of Buildings, Highways, Bridges, Power Plants, etc is needed in a big way. Generally, Construction has a major share in developing infrastructure in any Country. Accordingly, in the next five years, infrastructure in India will need an expenditure of more than $ 20,000 billion. Rapid infra-structural development requires huge construction materials, in which Concrete is preferred as it has longer life, low maintenance and better performance. Concrete is also the largest construction material used all over the world, as this can be used in any shape, grade or strength and any where on land or sea.

3 Presently, the construction industry is using more and more natural resources for producing aggregate required to make Concrete which come from breaking of stones in hills. Waste material generated from Building demolition etc is not put back to use. Huge quantity of demolition waste generated can be collected and put to use in construction. Recycling of demolished waste can offer not only the solution of growing waste disposal problem, but will also help to conserve natural resources like stones from hills, crude oil/energy which is required in Operation and Transportation at hillocks and throwing the Construction Waste (Called MALWA in India) as land fill. This will also Percentage of concrete ingradients help in meeting increasing demand of aggregates; protect environment and maintain ecological Water 6% balance in hilly areas Cement 13% CONCRETE CONSTRUCTION Concrete is a heterogeneous material which is made with Cement, (Stone Chips), Sand & Water. A typical distribution of constituent materials in concrete is given in figure 1. Out of the total ingredients in mix, about 50% is Coarse. As all these materials are not available in plenty and some of them are energy intensive, so their use should be economized. Sand 32% Sand Cement Water 49% Figure 1- A Typical distribution of ingredient materials in Concrete Mix AVAILABILITY OF FRESH AGGREGATE & DEMOLITION WASTE (MALWA) FOR PRODUCING CONCRETE Presently, the construction industry world wide is using natural resources to make aggregate or collect them from river bed as pebbles. Environmentally such rocks / material should not be disturbed as far as possible. If we break more & more hillocks, then there will be indirect effect on environment like deforestation, floods etc. Further, the cost of construction is continuously increasing due to increasing cost of materials and energy. In many places, supply of good quality aggregate is depleting, and is to be brought from longer distances which greatly increase the hauling cost and hence Fuel Energy required, which increases the construction cost. Presently, due to huge developmental work being carried out and construction to go on for ever, stone aggregates are required for the many Centuries to come and there may be a shortage of natural aggregates after few centuries. Therefore, for conservation of natural resources and protection of environment, it is necessary that alternate sources of aggregates be searched which is necessary for any developing/developed country. Figure 2 Dump of Demolition/Solid Waste On the other hand, huge amount of demolished waste is generated everyday. Central Pollution Control Board has estimated current quantum of solid waste generation in India to the tune of 50 million tons; out of this, waste from construction industry accounts for more than 35%. A typical demolition waste dump is shown in figure 2. Disposal of such high quantum of waste puts enormous pressure on solid waste management system and energy required for processing. The basic composition of Solid waste or Garbage varies in composition from place to place and from time to

4 time, but a typical distribution of basic constituents in solid waste is shown in figure 3. Though, the organic waste can be put to use for making Bio-gas & Manure and Metal pieces & Polyurethane for recycling, but demolition waste or MALWA is not put to use anywhere. However, to do all these ORGANIC MATTER 10% SOIL / DUST 25% METAL 2% PLASTICS 1% WOOD 2% OTHERS 10% MALWA 50% Figure 3- Typical composition of Solid waste or Garbage processes, it is necessary to sort the Solid waste in different categories. This is also the need of hour and is being done in most advance Countries. In general, demolition waste (MALWA) gets mixed up with organic waste or garbage, so it becomes difficult to process the garbage even for organic manure or biogas or for any other proposes. However, by observing little precaution during demolition or renovation of Buildings, the sorting process or recycling can be easier. It is also desirable to recycle demolition waste (MALWA) on the spot itself to save energy in transportation and product produced in the form of Recycled can be economically used in nearby places of Construction itself. NEED FOR PRESENT STUDY AND IMPLEMENTATION Coarse : Normally coarse is the fractured stone obtained from rocks in hills or pebbles from river bed, and because of depletion of good conventional aggregate in certain regions, the need for development of Recycled technology should be taken up commercially. It is similar to fly ash, which is available from electrostatic precipitators of various super thermal power stations which is an industrial waste material. It is chemically reactive when, mixed with cement for use in concrete. This is also useful as partial replacement of cement, as it gives concrete having better impermeability. Thus, it has a wider use in Construction Industry. Similarly, large scale recycling of demolished waste will offer, not only the solution of growing waste disposal problem and energy requirement, but will also help construction Industry in getting aggregates locally. Such demolition waste can be crushed to required size, depending upon the place of its application and crushed material is screened in order to produce recycled aggregate of appropriate sizes. An aggregate produced by demolished buildings will be called Recycled s. EXPERIMENTAL INVESTIGATIONS Materials and Material Properties: Experimental investigations are carried out by the author, so as to develop the methodology for conversion of demolition waste to recycled aggregate. In the present investigation, conventional and local aggregate are also taken on parallel basis. Thus, following three materials are tried. 1. Conventional ; (Dolomite stone from DALA Quarry in UP). 2. Local ; (Sand stone from MEZA Quarry in UP). 3. Recycled ; (Broken Building Part MALWA). Typical photographs of these aggregates are shown in Figure 4. All these materials have been tested for their physical properties like aggregate impact value, specific gravity, water absorption, bulk density etc. These are given in table 1. It is seen that specific gravity of Recycled aggregate is about 73% of DALA aggregate and 90% of local aggregate. These values of recycled aggregates will very from place to place and from time to time.

5 MALWA AGGREGATE MEJA AGGREGATE DALA AGGREGATE Figure 4- Typical Shape & Color of Three Different Source of Demolition Waste was collected from buildings being broken for renovation. The foreign matter was sorted out from solid waste (MALWA) and broken into the pieces of approximately 20 & 10 mm size with the help of hammer. On large scale this can be done by light Crusher. Then such aggregate was mechanically sieved through IS sieve of 26.5 mm and 4.75 mm to remove higher & finer particles. The higher size can be broken again and finer particles separated out can go back to river bed in the same trucks which bring sand from river. Table 1 Physical Properties Of MALWA And Other Used In Concrete Mix Description of Material Material Source Specific Gravity Water Absorption (%) AIV (%) Average FM 20 mm 10 mm Bulk Density (gm/cc) Conventional Local Recycled Sand DALA Quarry MEJA Quarry Dismantl ed House JAMUNA River (Zone II) 1.65 PROPOSED USES OF DEMOLITION WASTE: Recycled aggregate has been tried for the following three uses. In each case Concrete mix was prepared with OPC 53 grade cement, river sand and bore well water. No chemical admixture was used in any of the concrete mix. a. Recycled aggregate for making conventional Bricks b. Recycled aggregate in general concrete Construction c. Recycled in Construction of Highway Pavement. All these options are discussed here. A) USE OF RECYCLED AGGREGATE IN MAKING BRICKS / BLOCKS: The MALWA concrete was tried for making conventional Bricks. A typical concrete mix was designed in Recycled aggregate at different cement contents. Finally cement content of 160 Kg/cum of Concrete was chosen. The details of mix are given in table 2. Table 2 - Concrete Mix Design for Casting Bricks in Recycled Description Cement Sand Cement W/C (Kg) 20 mm (Kg) 10 mm (Kg) (Kg) Ratio (%) MALWA

6 Figure 5 - Typical Shape of Bricks made with MALWA Concrete All these material were taken for a smaller batch of concrete and weighed as per design requirement. Materials were mixed in laboratory mixture. Bricks were cast as per the conventional brick making. Bricks were cured in open with water spray a few times in the day. Shape of typical bricks is shown in figure 5. The Bricks were tested after 7 days. Each Brick was also weighed and concrete density calculated. Then these bricks were used in layers for wall making as shown in figure 6. The wall is performing well. Discussion of Results: For the comparison of efficiency of MALWA concrete bricks, the conventional burnt clay bricks in Ist quality were also taken and tested. The details of investigation are discussed in the following heads. 1. Compressive Strength 2. Density of Bricks 3. Failure Pattern / Fracture Mechanism Figure 6 - Typical Shape of Bricks put in layers as brick work i) Compressive Strength: After curing, the bricks were tested in compression in CTM. Few Conventional Clay bricks were also tested in the same procedure. Compressive strength in each case is summarized in Table 3. It is seen that Bricks made with Recycled aggregate, attains good strength and it is comparable with good quality clay bricks. Such strength of Brick is good for normal Construction of Buildings. Table 3: Comparative Strength of MALWA Concrete Bricks and Conventional Bricks Description Av. Strength (MPa) Density of Brick (g/cc) MALWA Concrete Bricks Conventional Bricks ii) Density of Bricks: Each Brick was weighed and its density was calculated. The density in both cases is also given in Table 3. It is seen that density is more when recycled aggregate is used. Such value is advantageous in the case of its use in load bearing wall, lining or on road Shoulders etc. iii) Failure Pattern / Fracture Mechanism: 1. The shape of crushed Recycled aggregate bricks is shown in figure 7. It is seen that the failure pattern of Recycled Bricks is similar as for typical Concrete. 2. It is generally seen that the failure occurs at the interface of aggregate & mortar and plaster lump pieces are broken Figure 7 - Failure Pattern of Crushed Bricks

7 B) Use of Recycled in General Concrete Construction A concrete mix with Conventional, Local and Recycled aggregate was designed in the grade of M 20 and M 25 with cement content of 250 & 300 Kg/cum. The quantities of ingredients are given in table 4 for M 25. All these materials were taken for a smaller batch and weighed as per design requirement. Materials were mixed in laboratory mixture. Cubes (150 x 150 x 150 mm size) were cast. They were cured and tested after 7 & 28 days. Each cube was also weighed and concrete density calculated. Table 4 - Design of general Concrete mix in different s (M 25) Description Cement River Sand W/C of (Kg) 20mm (Kg) 10mm (Kg) (Kg) Conventional Local Recycled Discussion of Results: The details of investigation are given in following heads. 1. Compressive Strength 2. Density of Concrete 3. Failure Pattern 4. Permeability of concrete i) Compressive Strength: Compressive strength in each case is summarized in Table 5. It is seen that all concrete mixes attain more than design strength (including recycled aggregate) ie more than 25 MPa in 28 days. The compressive strength further increases with time as seen in the table. It is found that such concrete with recycled aggregate can be used conveniently upto 25 MPa (equivalent to 1:1-1/2:3 concrete Mix) in general building construction. Table 5 - Compressive Strength of Concrete mix in different materials Average Compressive Strength (MPa) at Avg. Density Impermeability Material 7 day 28 day 60 day 90 day Weight of Coeff. (10-04 ) of cubes concrete (as defined) Conventional Local Recycled ii) Density of Concrete: Each cube was weighed and density of concrete calculated. The variation of density in each case is also given in Table 5. It is seen that density is maximum when conventional (DALA) aggregate is used and it is minimum when recycled aggregate is used. The maximum density is 2.51 g/cc and minimum is 2.25 g/cc. which is about 90% of fresh aggregate. iii) Failure Pattern: It is similar to what is given under bricks. iv) Permeability of concrete: Permeability of concrete is determined using method described in Specifications for Road & Bridge Works of Indian Road Congress. For this 3 cylinders, of 150mm diameter & 160mm height were cast and cured. They were fixed in permeability apparatus as shown in figure 8. Water pressure of 7 Kg/cm 2 was applied for 96 hours in the Permeability Apparatus. Figure 8 - Permeability Apparatus After 96 hours cylinders were taken out and split under line load in Compression Testing Machine. A typical split cylinder is shown in figure 9. In this figure, the effect of water penetration is shown at top and marked by black line. The depth of penetration of water in cylinder was observed & measured as well as volume of water lost from original level in the intake tube is recorded. The results are calculated as:

8 1. Measure the depth of penetration of water in permeability cylinder. 2. Coefficient of impermeability is calculated as Impermeability coefficient = vol. of water lost in tube / (Average depth of water penetration in concrete x X-area of cylinder) The impermeability of concrete, as defined above, is shown in table 5. It is observed that impermeability coefficient is comparatively low and this is comparable with other type of aggregates. Figure 9 - A typical shape of split cylinder Use in Some Utility Items: Such concrete can be used in general residential buildings and similar other places. Few utility items like Shallow tubs, Flower pots etc were cast with such Recycled Concrete. They are shown in figure 9 and used at site. Figure 10 A typical Shallow Tub and Flower Pot made with such Concrete C) Use of Recycled In Highways Construction: Highways are the biggest user of aggregate, so to see the possibility of its use in Highway construction, investigations are carried out for use in the following components. 1. DLC (Dry Lean Concrete). 2. Embankment Drainage Components. a) DLC (Dry Lean Concrete): The Concrete mix parameters of Recycled aggregate along with conventional and local materials were determined for DLC mix as given in table 6. The effectiveness of concrete mix of conventional aggregate is compared with Local and Recycled aggregate and its usefulness is seen from strength and compacted density consideration. Using these aggregates as in table 6, concrete mix was prepared in the smaller batch in laboratory requiring a minimum compressive strength of 10 MPa at 7 days (as required in Highway Construction) as per method described for DLC mix. Cubes were also caste and cured as usual. Table 6 - Design of Concrete mix for DLC in different materials Description of Cement (Kg) 20mm (Kg) 10mm (Kg) River Sand (Kg) Cement Ratio Conventional :1 Local :1 Recycled :1

9 Discussion of Results: The investigations are discussed in the following heads. 1. MDD & OMC of Mix 2. Compressive Strength and concrete density. i) MDD & OMC of DLC Mix: The DLC Mix was filled in the cubes with the help of vibratory hammer at different moisture contents. The weight of cubes was taken. The values of Maximum Dry Density and moisture content were calculated as per conventional procedure. Several trials were made at different moisture contents. All these values compare very well as given in table 7.So the aggregates can be effectively used in highways. Table 7 - OMC, MDD and Compressive Strength of DLC Cubes Observation / Units Conventional Local Recycled Average 7 day Strength MPa Avg. Weight of cubes Kg Density of concrete g/cc OMC % Maximum Dry Density (MDD) g/cc ii) Compressive Strength: Cubes were tested after 7 days. It is seen that all the mix attain more than required Cube strength of 10MPa. It is seen that even the Recycled aggregate mix attains more than the design strength. Each cube was also weighed and concrete density calculated as given in Table 7. b) Use of Recycled In Embankment Drainage Components: With the success of its use in DLC, the MALWA concrete as per design (Table 8) was tried for casting chute drain, median drain & side drain components. Few Chute drain Components were precast in laboratory with M25 mix and is shown in figure 11. This has also been used at site as shown in figure and is performing very well. Table-8 - Design of Concrete mix in different materials (M 25) Description Cement (Kg) (Kg) Sand (Kg) W/C Conventional Recycled Figure 11 - A typical shape of Drainage Component made with Recycled in single and assembled form

10 CONCLUSIONS AND ADVANTAGES OF USING RECYCLED AGGREGATE Based on the present investigations on Recycled s, the following conclusions can be drawn. Some advantages of using Recycled aggregate in Concrete Construction are also given. 1. Disposal of Demolition Waste / GARBAGE becomes easier. 2. We can make concrete blocks, like burnt clay bricks out of this type of concrete. By making bricks, the manufacture of conventional clay bricks can be reduced & hence top Soil, which is suitable for Agriculture, can be conserved. This will automatically preserve green environment and save energy. 3. Recycled aggregate can be used in reinforced concrete or Plain Concrete in foundation, Retaining walls, Panel walls etc. 4. Highways are the biggest user of aggregates where it can be used for dry lean concrete (DLC), Shoulder, and paving blocks and in side drains etc. 5. Finer material after crushing of demolition waste and sieving through 4.75 mm IS sieve; can go back to river beds in the same trucks which bring sand from river. 6. It will save the natural resources like Hillocks, River Pebbles etc from extinction. 7. Stone queries or Hillocks will not be affected and hence environment can be preserved. Resulting floods and droughts will be minimized & thus less Deforestation of hilly areas. 8. It can keep the roads and streets clean by not dumping Demolition Waste on the road side as in India. This will also minimize Road accidents because of fewer obstructions. 9. It can generate work for unemployed people like collecting MALWA by Rag pickers and deposit it at Ready Mixed Concrete Plants (shown in Fig 12) who will get some. 10. For enforcing the use of Recycled in Construction, studies on long term properties of the Recycled should be done for their properties. 11. Based on such studies, Formulation of Specifications and Codal provisions be done. REFERENCES 1. Marek, C. R. Gallaway, B. M. and Long, R. E., Look at Processed Rubble It is a Valuable Source for s, Roads and Streets, Vol. 114, No. 9, Sept. 1971, p Barra, M and Vazquez, E, Properties of Concrete with Recycled s : Influence of the Properties of the s and Their Interpretation, Proceedings of the International Symposium organized by the Concrete Technology Unit, London, Ghosh, S. N., Progress in Cement and Concrete, Science & Technology, Thomas Telford, Pt. I, Vol. I, Rao, Akash; K.N Jha, and Sudhir Misra; A framework for use of construction and demolition waste as recycled aggregate in India, The Indian Concrete Journal, January, ACKNOWLEDGEMENTS The work has been carried out in the site laboratory of M/s HCC, Allahabad Bypass project.

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