Department of Chemistry
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Item Influence of incorporation of nano-silica and recycled aggregates on compressive strength and microstructure of concrete(Elsiever, 2014-11-30) Barai, Sudhir KumarThe present investigation deals with the study of compressive strength and characteristics of the Interfacial Transition Zone (ITZ) of concrete containing recycled aggregates and nano-silica. For this purpose, compressive strength at 7, 28, 90 and 365 days are determined for fully natural and recycled aggregate concrete mixes made with or without nano-silica. In addition to above, Vickers microhardness test and backscattered-mode scanning electron microscopic analysis is carried to characterize ITZ of concrete mixes. The results of study depict that full replacement of natural coarse aggregates with recycled ones have significant effect on compressive strength and ITZ characteristics of concrete. However, compressive strength and microstructure of concrete mixes improves with the incorporation of nano-silica.Item Behaviour of recycled aggregate concrete under drop weight impact load(Elsiever, 2011-01) Barai, Sudhir KumarThis paper presents the experimental results of recycled aggregate concrete (RAC) beams prepared with different amount of recycled coarse aggregate (RCA) subjected to low velocity impact. The recycled coarse aggregates are obtained from a demolished RCC culvert. Four concrete mixes with 0%, 25%, 50% and 100% RCA respectively are prepared. With each mix three beam specimens of size 1.15 × 0.1 × 0.15 m are prepared and tested under drop weight impact load. The behavior of the RAC beams are studied in terms of acceleration, strains and support reaction histories under impact load in addition to the physical and mechanical characteristics of RCA and RAC. It is observed that 25% RCA does not influence the strength of concrete. In addition, it is found that for a given impact energy (the energy imparted by the hammer per blow) the reactions and strains of RAC with 50% and 100% RCA are significantly lower and higher respectively than those of normal concrete and RAC with 25% RCA.Item Assessment of the influence of Nano-Silica on the behavior of mortar using factorial design of experiments(Elsiever, 2014-10) Barai, Sudhir KumarThe influence of water/cement ratio and addition of Nano-Silica as partial replacement of cement on the compressive strength and water absorption of mortar mixes is a topic of current research. For this purpose, 32 factorial design is selected with water/cement ratio and Nano-Silica (%) as factors. The levels of water/cement ratio are kept at 0.40, 0.45 and 0.50. The levels of other factor Nano-Silica (%) is kept at 0%, 1.5%, and 3%. Compressive strength at 3, 7, and 28 days and water absorption at 28 days are selected as responses. The Analysis of Variance (ANOVA) of test results for aforementioned responses considering the factors depict that the selected factors are significantly affecting the test results. However, the analysis indicates that interactions of factors are not statistically significant. In addition to the above, the study illustrates that consistency and setting time of cement paste is considerably affected by the incorporation of Nano-Silica.