Cement Energy and Environment

-+- 0,0,0 --- 0,20,10 0 0 20 40 eo eo 100 120 % ol light wolght aggrogato F19 3 V nation of flexu111l 'j\rength w1th Drcenta9e of light weight aggregate ll%f1brol Trlplo blanding •.. 0.5% tlbro x- 1% tlbro ao~-----------------------~~~-----­ aoo+-----------.e----7'~-----­ '700-t-------------Jf--------- JOOO )o01M-----~~~------------ ~ig. &, bPE!Q ve r~es gefle<;tiPR e;yr-v~ f~F ~0% rep(e·zemenl l)f n~tyr11( E!Q~re: g11tewith f34fl'll~?e 11ncl ct<lditioA ~?f 9 ~% e~n(;j 1 0% ef fi~Fe !Tnple ~leAglngl Weight Reduction of Concrete with Light Weight Aggregate With 25% light weight aggregate the weight of concrete is reduced by 11 .64% and with 100% light weight aggregate there is a reduction of 34.13% in unit weight. With 20% fly ash and 10% CSF respective reductions of 3.61%, 6.42%, 18.07, and 30.92%. Compared to concrete specimens without triple blending the reductions are less with triple clending as fly ash and silica fume being very fine, contribute in producing a denser concrete mix. When fibres are added in the mix, they have contributed towards increase in the unit weight of concrete. On the whole, it can be stated that mineral admixtures have increased the weight and fibres have further increased the weight. Compressive Strength of Various Combinations The 28 day compressive strength of concrete is 38.73 N/mm2 . When conventional aggregate is replaced by 25%, 50%, 75% and 100% of light weight pumice aggregate the respective strengths are reduced by 12.88%, 30.42%, 56.88%, and 60.88% respectively. It can be seen that the compressive strength of concrete is reduced because of low crushing value as well as low impact value . However 50% replacement of conventional aggregate by light weight aggregate is giving compressive strength of 26.95 N/mm2 , which is good enough for road applications. When mineral admixtures of 20%fly ash and 10% of CSF are added the respective values are 44.15, 39.18, 33.00, 23.24 and 16.48 N/mm2 Hence use of mineral admixture like fl y ash up to 20% and CSF up to 10% is contributing towards increase in the compressive strength. For replacements of 25%, 50%, and 75% the compressive strengths are increased by 17.5%, 22.44% and 39.16%, when 20% fly ash and 10% CSF are added compared to the mixes without admixtures. There are further increases marginally in the compressive strength with 0.5% and 1% fibres. Split Tensile Strength of Various Combinations Compared to reference mix (without admixture and without fibre), 0.5% and 1% fibres have increased the split tensile strength by 34.41% and 43.8% respectively. With 20% fly ash and 10% CSF in the mix the increase in the split tensile strength value of the reference mix without fibre is 80.8%. With 0.5% and 1% fibre in the mix with admixtures split tensile strength values are increased further by 9.59% and 25.04% respectively, compared to the reference mix the overall increase in the split tensile strength with admixture and with 0.5 and 1% fibres are 98.23% and 126.1% respectively. so • ' •