Utilization of demolished waste as fine aggregate in Concrete

J. Acad. Indus. Res. Vol. 1(7) December 2012 398RESEARCH ARTICLEISSN: 2278-5213Utilization of demolished waste as fine aggregate in ConcreteMohd Monish 1 , Vikas Srivastava 1 , V. C. Agarwal 1 and Rakesh Kumar 21 Civil Engg. Department, SHIATS (formerly AAI-DU), Allahabad-211007, UP2 Civil Engg. Department, MNNIT, Allahabad-211004, UP, Indiagautam.civil2009@gmail.com; +919415369170______________________________________________________________________________________________AbstractDemolition of old structures to make way for new and modern ones is common features in metropolitan areasdue to rapid urbanization. Very little demolished concrete is recycled or reused. Due to strict environmentallaws and lack of dumping sites in urban areas, demolished waste disposal is a great problem. The study is apart of comprehensive program wherein experimental investigations have been carried out to assess the effectof partial replacement of fine aggregate by demolished waste on workability and compressive strength ofrecycled concrete for the study, at a period of 7 and 28 d. The compressive strength thus observed has beencompared with strength of conventional concrete. Test results showed the compressive strength of recycledconcrete with 10% fine aggregate replacement by demolished waste at the end of 28 d has been found to bemarginally lower than that of conventional concrete.Keywords: Old structures, workability, recycle aggregate, compressive strength, conventional concrete.IntroductionAmidst growing awareness on protection of environmentand conservation of natural resources and this study is anattempt to explore recycled concrete as a material ofhope for 21 st century. Demolished waste obtained from astructure mainly made up of concrete has several foreignmatter such as various type of finishes, claddingmaterials, lumber, dirt, steel, hardware’s, woods, plasticsetc, attached to them directly or indirectly. The process ofremoval of impurities and crushing of rubble into suitableand desirable aggregate particle size can be carried outin a continuous and sequential manner using appropriatemechanical devices such as jaw crushers, impactcrushers, swing hammer crushers etc. There are threeprocesses, for processing of demolished waste: Dry, Wetand Thermal, which are used individually or incombination with one another. Due to high waterabsorption of recycled aggregates, it is sometimessuggested to use pre-soaked aggregates for productionof recycled aggregate.Hansen and Marga (1992) found that based on equalslump, the water requirement of recycled aggregateconcrete made with both coarse and fine recycledaggregate was 14% higher than that of control concretesmade with natural sand and gravel. When concrete wasproduced with coarse recycled aggregate and naturalsand, the increase in water demand was only 6%.Masood et al. (2001) compared the strength andeconomy of standard and recycled concrete with partialreplacement of cement and fine aggregates. Therecycled concrete achieved up to 77% compressivestrength, and above 90% for splitting tensile andflexural strength and a cost saving of 15%.These indicate the potential of C and D wastes asvaluable building materials on technical,environmental and economic grounds. Khalaf andDeVenny (2004) concluded that concrete can besuccessfully produced using recycled aggregates thathave been produced from demolition and constructionwaste. Concrete produced with these aggregates doesnot perform as well as concretes produced with naturalaggregates in terms of strength. However, concrete stillhas a strength that would make it suitable for someapplications, with the added benefit that density valuesare much lower; making it suitable in situations whereself-weight is a problem and very good fire resistance isrequired. Against these backdrops, this study was aimedto assess the effect of partial replacement of fineaggregate by demolished waste on workability andcompressive strength of recycled concrete for t a periodof 7 and 28 d.Materials and methodsDemolished waste: Demolished waste was collectedfrom IIT Building near Jhalwa Allahabad, India.Demolished waste on being tested in laboratory showedpozzolanic properties. Demolished waste as a pozzolanicmaterial was used to partially replace cement andsimilarly fine aggregate. Properties of recycledaggregates are given in Table 1.Cement: In this work, ordinary Portland cement of Birla(43 grade) brand obtained from a single batches troughout the investigation was used. The ordinary cementcontent mainly has two basic ingredients namely,argillaceous and calcareous. The physical properties ofOPC as determined are in Table 2. The cement satisfiesthe requirement of IS: 8112-1989.©Youth Education and Research Trust (YERT) Mohd Monish et al., 2012

J. Acad. Indus. Res. Vol. 1(7) December 2012 399Table 1. Physical properties of recycled aggregate.PropertiesObserved valuesColourPinkish brownSpecific gravity 2.5Water absorption (%) 3.03-4.5Table 2. Properties of cement.PropertiesRequirementObservedas pervaluesIS:8112-1989Normal consistency - 28%Initial setting time 30 min 113 minFinal setting time 600 min 317 min3 d compressive strength 23 N/mm 2 23.67 N/mm 27 d compressive strength 33 N/mm 2 34.67 N/mm 228 d compressive strength 43 N/mm 2 44.33 N/mmSoundness test Up to 10 mm 2.5 mmFineness test (90 µ sieve) Up to 10% 0.98%ISsievesizeTable 3. Sieve analysis (Fine aggregate).Weight Cumulativeretained weight(g) retained (g)% cumulativeweight retained10 mm 0 0 0.004.75 mm 110 110 11.002.36 mm 52 162 16.201.18 mm 175 337 33.70600 µ 128 465 46.50300 µ 250 715 71.50150 µ 240 955 95.50ISsievesizeTable 4. Properties of fine aggregate.PropertiesObserved valuesFineness modulus 2.74Specific gravity 2.63Table 5. Sieve analysis (Coarse aggregate).WeightCumulativeretainedweight retained (g)(g)% Cumulativeweightretained16 mm 0 0 0.0012.5 mm 124 124 2.4810 mm 1186 1310 26.204.75 mm 3520 4830 96.602.36 mm 115 4945 98.901.18 mm 55 5000 100.00600 µ - 5000 100.00300 µ - 5000 100.00150 µ - 5000 100.00Table 6. Properties of aggregate.PropertiesObserved valuesFineness modulus 6.22Specific gravity 2.64Fine aggregate: The fine aggregate is locally availableriver sand, which is passed through 4.75 mm sieve.Result of sieve analysis of fine aggregate and physicalproperties are given in Table 3 and 4 respectively.Coarse aggregate: The coarse aggregate locallyavailable crushed stone aggregate, 12 mm maximum ofsingle lot size has been used trough out the experimentthe specific gravity of coarse aggregate was 2.7. Thegrading of coarse aggregate are given in the Table 5 and6.Water: Potable water is used for mixing and curing. Onaddition of higher percentage of demolished waste therequirement of water increases for the same workability.Thus a constant slump has been the criteria fir waterrequirement but the specimens having 0% demolishedwaste, w/c of 0.50 has been used.Concrete: The concrete mix design is done inaccordance with IS: 10262 (1982). The cement contentin the mix design is taken as 380 kg/cu. m 3 whichsatisfies minimum requirement of 300 kg/cu. m in orderto avoid the balling effect. Good stone aggregate andnatural river sand of zone-II was used as coarseaggregate and fine aggregate respectively. Maximumsize of coarse aggregate was 12.5 mm. a sieve analysisconforming to IS: 383-1970 was carried out for both thefine and coarse aggregate. This study is a part ofcomprehensive programme wherein experimentalinvestigations have been carried out to assess the effectof replacement of regular material by a cheaper substitutei.e. demolished waste on strength of concrete. For thisstudy cubes of 100 mm size were cast by replacing fineaggregate by demolished waste. Compressive strength ofthis recycled concrete were observed and compared withthose of natural aggregate concrete. To achieve thiscomparative study, cubes were cast replacing fineaggregates by 10%, 20%, and 30% with demolishedwaste for a comparative study with respect toconventional concrete. These specimens were testedafter 7 and 28 d. To identify cube strength, a mixproportion of 1:1.67:3.33 was used during theinvestigation.Results and discussionThe observations made during the test of cubes aresummarized as workability and compressive strength arepresented in tabular form (Table 7). Three specimens eachhaving 0%, 10%, 20%, and 30% demolished waste as fineaggregate replacement for mix of 1:1.67:3.33 were castand tested after 7 days and 28 d in order to have acomparative study.Workability: Workability is the relative ease with whichconcrete can be mixed, placed, compacted and finished.While casting specimens, slump test were carried out todetermine the workability of different samples as perIS: 6461-1973 (Fig. 1).©Youth Education and Research Trust (YERT) Mohd Monish et al., 2012

J. Acad. Indus. Res. Vol. 1(7) December 2012 400Table 7 shows the variations of slump with water cementratio for recycled concrete mixes.Table 7. Slump and average compressive strength of concrete.Types of concreteAverage compressivestrength (N/mm 2 Slump)(mm)7 d 28 dConventionalconcrete (0% DW)33 38 3010% F.A.R. concrete 31 36 2620% F.A.R. concrete 28 33 2530% F.A.R. concrete 27 31 22Compressive strength: Cubical specimens were cast forthe determination of compressive strength. Theseobservations are presented in tabular form as compressivestrength values (Table 8). Cubes up to 20% of fineaggregate replaced by demolished waste give strengthcloser to the strength of plain concrete cubes and strengthretention of 86.84% for recycled concrete mix (Fig. 2).Table 8. Comparative statement of strength andeconomy (mix 1:1.67:3.33).ItemsStrength(KN/mm 2 )Cost per m 3(Rupees)Decreasein cost(%)Natural concrete 38 3613.32 -Recycled concretewith 10% fineaggregatereplacementRecycled concretewith 20% fineaggregatereplacementRecycled concretewith 30% fineaggregatereplacement36 3537.52 13.1833 3559 1.5031 3390 6.18ConclusionThe following conclusions are drawn from the experimentalstudy.1. Recycled aggregate concrete may be an alternative tothe conventional concrete.2. Water required producing the same workabilityincreases with the increase in the percentage ofdemolished waste.3. Optimum replacement level of fine aggregate withrecycled aggregate is 10%.Fig. 1. Workability of various percentage of F.A.R. concrete.Slump (mm)Compressive strength (KN/mm 2 )353025201510500% F.A.R.Concrete10% F.A.R.Concrete20% F.A.R.Concrete30%F.A.R.concreteFig. 2. Compressive strength of various percentage ofF.A.R. concrete.40353025201510507 Days Compressive strength 28 Days Compressive strength0% F.A.R.Concrete10% F.A.R.Concrete20% F.A.R.Concrete30% F.A.R.ConcreteReferences1. Hansen, T.C. and Marga, M. 1992. Strength of recycledconcrete made from coarse and fine recycled concreteaggregate. Ibid .135: 605-612.2. IS: 456-1978. Code of practice for plain and reinforced concrete.Indian Standard Institute, New Delhi.3. IS: 6461-1973. Properties of concrete (part VIII). Indian StandardInstitute, New Delhi.4. IS: 8112-1989. 43 Grade ordinary Portland cement. IndianStandard Institute, New Delhi.5. Khalaf, F.M. and DeVenny, A.S. 2004. Performance of brickaggregate concrete at high temperatures. J. Mater. Civil Engg.16(6): 556-565.6. Masood A., Ahmad, T., Arif, M. and Mahdi, F. 2001. Wastemanagement strategies for concrete. Environ. Engg. Policy. 3:15-18.©Youth Education and Research Trust (YERT) Mohd Monish et al., 2012