paper done by, 1. Abdul Basit Khan ,2. TusharRaju, 3. Raunak Singh Suri “1, 2- Students of S.
I.R.T.S. , 3.- Student of N.I.T.
T.T.R. Abstract — The concrete is made up thecombination of fine aggregate, coarse aggregate, cement and water. And is themajor part of construction. A large amount ofdemolished waste is generated every year in India due to the rapid developmentof infrastructure. Since a very small amount of this waste is recycled, soplacing this waste is a very serious problem because it requires a large amountof space. This paper is a part of comprehensive program where the experimental arecarried out to evaluate the effect of partial replacement of coarse aggregateby demolished waste concrete on compressive strength and workability of DAC(Demolished Aggregate Concrete).
For that 7, 14 and 28 days compressivestrengths were recorded. The earlier study on this project shows that thecompressive strength of the DAC (Demolished Aggregate Concrete) somehowresembles with the conventional concrete if used in a proper amount up to 30%.So in this study we have taken the demolished concrete aggregate 10%, 20%, 30%by weight of the approved coarse aggregate and the concrete cubes were casted bythat demolished concrete aggregate then further tests conducted such as workability,compressive strength for that DAC and the result obtained are found to becomparable with the conventional concrete. OVERVIEWDue to development ofindustries and urban areas waste generation is also increased, which isunfavorable for the environment. This study deals with recycling and reusing ofwaste concrete that is collected from buildings that are demolished andcollapsed. The main aim of this paper is to reduce the use of naturallyavailable river soil which is used as fine aggregate for producing concrete. Thereis a shortage of about 55,000 million m3 due tothe construction of new infrastructure which shows that the demand of theaggregates in future increases. 750 million m3 additionalaggregate is required to fulfill the demand of the road sector.
There is a hugegap between the demand and the During construction waste generated is about 40kg per m2 to 60 kg per m2. Similarly, during renovation,repair and maintenance work 40 kg/m2 to 50kg/m2 waste is generated. The waste generated due to demolition of thebuilding is highest among all the wastes.
If we demolish permanent buildingabout 300kg/m2 waste is generated and in case of demolition of semi-permanentbuilding 500kg/m2 waste is generated. The current concrete construction practice isthought unsustainable because, not only it is consuming enormous quantities ofstone, sand, and drinking water, but also two billion tons a year of Portlandcement, which releases greenhouse gases. Experiments has been conducted forwaste materials like- rubber tires, e-waste, coconut shell, blast furnace slag,waste plastic, demolished concrete constituents Environment must be protectedfor the survival of the human beings and other lives on earth. So environment consciousness,sustainable development and preservation of natural resources should be kept inmind during the construction work and industrialization. At present, demolishedmaterial are dumped on land or treated as waste, which means they cannot beutilized for any purpose. If we put the demolished waste on land then thefertility of the soil get decreases. 23.75 million tons of waste is generated annuallyin India in the year of 2007 according to Hindu Online.
According to CPCB(Central Pollution Control Board) Delhi, 14.5 million tons out of 48 million wasteis generated from the construction waste from which only 3% is utilized in theconstruction of the embankment. In 100 parts of the construction waste 40 partsare of concrete, 30parts of ceramics, 5 parts of plastics, 10parts of wood, 5parts of metal and 10 parts of some other mixed compounds. But the currentmethod adopted for the management of this waste are landfill mainly whichcauses a giant amount of the construction and demolished waste deposition andsuch huge amount affects the environment adversely. In India concrete, bricks,sand, mortar and tile residues are the main materials found in the demolishedwaste of buildings.
This waste can be recycled or process in to the recycleddemolished aggregates which can be utilized in the concrete mixes. Demolishedconcrete aggregate (DCA) is generally produced by the crushing of concreterubble, then screening and removal of contaminants such as plaster, paper, reinforcements,wood, plastics. Concrete made with this type of recycled demolished concreteaggregate is called Demolished aggregate concrete (DAC). The main purpose of This study is todetermine the basic properties of DAC made of coarse recycled demolishedconcrete aggregate then to compare them with the properties of concrete madewith natural aggregates concrete. Fine recycled aggregate cannot be applied inthe concrete which is used for structures so we can ignore its amount 70-75%aggregates are required for the production of concrete. Out of this 60-67% isof coarse aggregate & 33-40% is of fine aggregate. India is in the top 10 usersof the concrete due to rapid growth of infrastructure. As the demolishedaggregate is lighter than the natural aggregate so the concrete made from suchaggregate possesses low density but the water absorption of the demolished aggregateis higher than the natural aggregate and the strength of the demolishedaggregates is somehow lesser than the natural aggregates.
So concrete made fromthese demolished aggregate can be utilized where more strength is not required e.g.in low rising buildings, in reinforced concrete pavements etc. MATERIALSAND METHODOLOGYDemolished waste: Demolishedconcrete waste is collected from /residential building in Rajatnagar Bhopal(m.p.). It is light grey in color. Fig(a)DemolishedConcrete Aggregate Properties ofDemolished Aggregates: i.
Specific Gravity:The crushed concrete is taken andis sieved through 4.75mm sieve and the amount passed is taken for testing. The specific gravity in saturated surface dry condition of demolishedconcrete aggregate was found from 2.
45 which is less but satisfying theresults. If specific gravity is less than 2.4, it may cause segregation;honeycombing & also yield of concrete may get reduced. ii.
Water Absorption:The aggregate isimmersed in water for 24 hours and then the weight of the wet aggregate isnoted. The aggregate is placed in an oven anddried for 24 hours and the dry aggregate weight is noted. This gives the waterabsorption of aggregate. The water absorption of aggregate is 1.8%, which iscomparatively more than that of the natural aggregates.
The DCA from demolishedconcrete be made of crushed stone aggregate with old mortar adhering to it.Thus the water absorption results are satisfactory. iii. Bulk Density:The bulk density ofdemolished aggregate is lower than that of natural aggregate, thus results arenot satisfactory;due to low Bulk Densitythe mix proportion gets affected. iv. Crushing and Impact Values:The demolishedaggregate is comparatively weaker than the natural aggregate against differentmechanical actions.As per IS 2386 part(IV), the impact and crushing values for concrete wearing surfaces should notexceed 30% &for other than wearingsurfaces 45% respectively. The crushing & impact values of recycledaggregate satisfythe BIS specificationslimit.
From crushing and impact test it is found that use of recycled aggregateis possiblefor application otherthan wearing surfaces. MIX DESIGN A mix design is a method ofcalculating the amount of coarse aggregate, fine aggregate, cement content andwater content is calculated by using the experimental values obtained. DESIGN STIPULATIONS: Mix of concrete is M20 The fck valve is 20N/mm2 Consider maximum aggregate sizeis 20mm Degree of workability = 0.90(compaction factor) Type of Exposure = Mildexposure Test data of material(to be determined in the laboratory): Specific gravity of cement =3.
15 Specific gravity of CA = 2.63 Specific gravity of RFA = 2.84 Water absorption: CA = 0.5 % RFA (recycled fine aggregate) =1.8 % Free (surface) moisture: CA = nil RFA = 1% Fine aggregates confirms tozone 2 IS-383 MIX DESIGN CALCULATIONS: TARGET STRENGTH: Constant for 5% risk factor is1.65. In this case standard deviation is taken from IS:456 against M 20 is 4.0.
ftarget =fck + 1.65 x S= 25+ 1.65 x 4.
0 = 31.6 N/mm2Where,S = standard deviation in N/mm2 =4 (as per table -1 of IS 10262- 2009) WATER CEMENT RATIO: From Table 5 of IS 456,(page no 20)Maximum water-cementratio for Mild exposure condition = 0.55Based on experience,adopt water-cement ratio as 0.5.0.
5<0.55, hence OK.DETERMINATION OF COURSE AND FINE AGGREGATE: CA = 1181.65kg FA = 579.
80 Kg Selection of Cement ContentWater-cement ratio = 0.5Corrected water content = 191.6 kg /m3Cement content =From Table 5 of IS 456,Minimum cement Content for mild exposure condition = 300 kg/m3383.2 kg/m3 > 300 kg/m3, hence, OK.This value is to be checked for durability requirement from IS: 456.In the present example against mild exposure and for the case ofreinforced concrete the minimum cement content is 300 kg/m3 whichis less than 383.
2 kg/m3. Hence cement content adopted = 383.2 kg/m3.As per clause 8.2.4.2 of IS: 456Maximum cement content = 450 kg/m3 MIX RATIO: The mix proportion of M25 found to be: Cement replaced aggregate coarse aggregates 372kg 579.80kg 1181.
65 kg 1 : 1.6 : 3.2 Actual quantities required for the mix per bag of cement: The mix is 0.
50: 1: 1.6: 3.2 For 50 kg of cement, thequantity of materials are worked out as below: Cement = 50 kg RFA = 77.
5 kg Coarse aggregates =159 kg Water = 25 lit Correctiondue to absorbing / moist aggregate:-Since the aggregate is saturated surface dry condition hence nocorrection is required. FRESHCONCRETE TEST: SLUMP CONE TEST: This test is used to measure the properties of fresh concrete. This is anempirical test that measures the workability of fresh concrete. It is used todetermine the consistency of the concrete. True slump achieved.
Slump 300mm Compaction factor 0.95. High workabilityconcrete, for sections with congested concrete, not normally suitable forvibration, Concrete Mixes Conventional Cubes: Volume of each cube = 3.375 x 10-3 m3 Volume of 3 cubes = 10.125 x 10-3 m3 Quantity of materials required (considering 10 % loss) Cement = 5 kg Sand = 7.7 kg Coarse aggregates =15.7 kg Water = 2.
5 litThe mix design is calculated and the amount of aggregate need for 9 cubesis calculated. The mix is done by hand by adding water at different intervalCOMPRESSIVESTRENGTH: The compressive strength of the concrete is tested for 7, 14 and 28 daysand the average value is taken. The compressive is done in compressive machineand the values are plotted in a graph along with the corresponding strength ofconventional M20 grade concrete at the same days of curing.
Compressivestrength N/mm2 CONCLUSION: Thus this paper clearly depicts the advantages of replacement ofaggregates with C&D waste concrete. The results of the compressive andtensile strength are comparatively higher than the conventional concrete. Thusby replacing the natural aggregate with the replaced waste can reduce theamount of pollution as well as preserve nature at all cost. Further test arebeing conducted for more research values. From the calculated results we canconclude that whatever is destroyed can be reused in a more effective mannerwithout causing any damage to the environment. Demolished aggregate possessrelatively lower bulkcrushing, density andimpact standards and higher water absorption as compared to natural aggregate.Tests conducted on demolished aggregates and results compared with naturalcoarse aggregates are satisfactory as per IS 2386.
The compressive strength ofdemolished aggregate concrete is relatively lower up to 15% than naturalaggregate concrete. Usingdemolished aggregate concrete as a base material for roadways reduce thepollution involved in trucking material. FUTURESCOPE1. Sustainabledevelopment of structures can beachieved by using wastedemolished concreteaggregate.2.
We can use theplastic waste also as a coarseaggregate in concrete.3. Fine aggregate in thedemolished concrete can alsobe utilized in future.
4. Demolished bricks andstones possess the sameproperties as coarseaggregates. III.RESULTS AND DISCUSSIONCompressive strength isthe maximum compressive stress that, under a gradually applied load, a certainsolid material can carry on without fracture. Compressive strength of 3, 7 and28 days of the DAC shown in the TABLE (III) for 0%, 10%, 20%, 30% replacementof the coarse aggregate by demolished concrete aggregate for M-30 mix. Threespecimens for each proportion were cast and tested for comparative study. For 30%replacement of coarse aggregate the 28 days compressive strength is 82.
65% ofthe compressive strength of conventional concrete. A concrete is termed asworkable if it is easily placed, transported, compacted, and finished without anysegregation. This property is tested by slump test. The results of slump testare mentioned in TABLE (IV) for different percentages of demolished concreteaggregate. The workability of the DAC is lower than the conventional concretebecause the rate of absorption of DA is higher than nominal aggregate. REFERENCES 1 Katz, A. (2003), “properties of concete made with recycled aggregate from partially hydrated oldconcete”, Cement Concrete Research, 33,703-11 2 “Demolition andReuse of Concrete and Masonry “, proceedings of Third International RELIMSsymposium,1993 3 Yuan, H. and Shen,I.
(2011), “Trend of the research on construction and demolition wastemanagement”, Waste Management 31 (4), 670- 679 4 Rao,A, Jha,K.N. andmisra S.
(2005), “Use of aggregate from recycled construction and demolitionwaste in concrete”, Recourses Conservation & recycling , 50(1)71-81. 5 Padmini,A. K .
,Ramamurthy. K, and Mathews ,M.S (2008), ” Influence of parent concrete on theproperties of recycled aggregate concrete”, Construction and Building Material,23 (2), 829-836.
