Department of Chemistry
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Item Recycled aggregate concrete: Particle Packing Method (PPM) of mix design approach(Elsiever, 2017-10) Barai, Sudhir KumarA sustainable and eco-friendly approach is essential for the construction industry, as it is one of the major sectors responsible for the depletion of the natural resources and the generation of greenhouse gases. In this context, the recycled aggregate (RA) is an effective alternative to natural aggregate. But, the use of RA has not gained popularity yet, because of the inferior quality of RA and yielded recycled aggregate concrete (RAC) using RA. The proposed Particle Packing Method (PPM) of design mix is executed along with the established Two Stage Mixing Approach (TSMA) to produce RAC by completely replacing the natural coarse aggregate. The synergistic effect of PPM design mix and TSMA on fresh and hardened stage performance of RAC were studied. In this context, a comparative analysis showed encouraging results for the PPM design mix as compared to the IS: 10262 (2009) method of mix design approach.Item Influence of Nano-Silica on the properties of recycled aggregate concrete(Elsiever, 2014-03) Barai, Sudhir KumarThe present work addresses the effect of incorporation of colloidal Nano-Silica on the behavior of concrete containing 100% recycled coarse aggregate. In this study, concrete mixes containing both natural and recycled aggregate are produced by replacing a fraction of Portland cement 0.75%, 1.5% and 3% of colloidal Nano-Silica respectively. The results of experimental investigation depicts that compressive strength, tensile strength and Non-Destructive parameters are enhanced due to addition of NS. Moreover, the study reveals that the characteristics of recycled aggregate concrete resembles with that of natural aggregate concrete with the addition of little amount (3%) 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 Influence of field recycled coarse aggregate on properties of concrete(Springer, 2010-05-06) Barai, Sudhir KumarThis paper investigates the influence of different amounts of recycled coarse aggregates obtained from a demolished RCC culvert 15 years old on the properties of recycled aggregate concrete (RAC). A new term called ‘‘coarse aggregate replacement ratio (CRR)’’ is introduced and is defined as the ratio of weight of recycled coarse aggregate to the total weight of coarse aggregate in a concrete mix. To analyze the behaviour of concrete in both the fresh and hardened state, a coarse aggregate replacement ratio of 0, 0.25, 0.50 and 1.0 are adopted in the concrete mixes. The properties namely compressive and indirect tensile strengths, modulus of elasticity, water absorption, volume of voids, density of hardened concrete and depth of chloride penetration are studied. From the experimental results it is observed that the concrete cured in air after 7 days of wet curing shows better strength than concrete cured completely under water for 28 days for all coarse aggregate replacement ratios.