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Kumar R.,Central Road Research Institute CRRI
Indian Concrete Journal | Year: 2016

As a consequence of ever increasing demand for quality aggregate for the construction of concrete based infrastructures many parts of the world are facing the problem of the scarcity of good quality aggregate for concrete. Among all alternate sources for aggregate, the recycling of construction and demolition (C&D) waste has an upper hand as it is available everywhere. A C&D waste is typically composed of wood, plaster, concrete, bitumen, roofing materials, glass, plastics, metal, insulating materials, and other similar materials depending on the locality of its origin. Recycled concrete aggregate derived from crushing of the concrete elements of C&D waste, is inhomogeneous unlike natural aggregate derived from a crushed rock. Thus, a thorough evaluation of physical and mechanical properties of such aggregate before using in concrete is needed. This study presents a comparative evaluation of recycled concrete aggregate (RCA) obtained from a commercial recycling plant with respect to a natural virgin aggregate in maximum size range of 10-20 mm. The comparison showed a significant reduction in the value of the specific gravity, bulk density, and abrasion resistance for the RCA. The water absorption of the RCA was more than eight folds to that of natural crushed aggregate. The study further presents the influence of 50% and 100% replacement of natural coarse aggregate with RCA on the compressive strength, flexural strength and water absorption of concrete mixes and concludes that 50% replacement of natural aggregate with RCA has insignificant influence on compressive and flexural strength of concrete but the overall durability of such concrete is inferior to the control concrete which limits its applicability. Source


Kumar R.,Central Road Research Institute CRRI | Bhattacharjee B.,Indian Institute of Technology Delhi
Indian Concrete Journal | Year: 2014

This paper describes the performance of Polypropylene (PP) multifilament vis - à - vis fibrillated fibre on slump, bleeding, settlement, compressive strength, flexural strength, drying shrinkage and abrasion resistance of concrete. Three different dosages of fibre i.e. 0.05%, 0.10% and 0.15% by volume were used in the study. The test results indicate that fibrillated fibre is more effective in reducing settlement of concrete in comparison with multifilament fibre. Further, a similar effect for both fibres on compressive strength, flexural strength and abrasion resistance of concrete was observed. However, a better performance for drying shrinkage control and energy absorbing capacity for the concrete reinforced with fibrillated fibre than multifilament fibre were noted. Source


Kumar R.,University of Wisconsin - Milwaukee | Kumar R.,Central Road Research Institute CRRI | Naik T.R.,Center for By Products Utilisation
Indian Concrete Journal | Year: 2014

Similar to other industrial manufacturing process, the production of Portland cement and concrete implies emissions of GHGs to the atmosphere in addition to a significant amount of consumption of natural resources. Consequently, cement and concrete industry is being held responsible as a significant contributor to the global climate change and a cause for unsustainable rate of depletion of natural resources. Manufacturing of concrete and its products have a significant impact on the environments since the manufacturing of the main constituent of concrete, Portland cement, is responsible for emission of about 7% of the total global anthropogenic carbon dioxide. The success of such technology depends on local conditions, norms, and practices. Understanding of the environmental issues in the manufacturing activities of concrete and its products are the main driving force for the advent of greener concrete. Source


Shah Y.U.,Indian Institute of Technology Roorkee | Jain S.S.,Indian Institute of Technology Roorkee | Tiwari D.,Central Road Research Institute CRRI | Jain M.K.,Indian Institute of Technology Roorkee
Airfield and Highway Pavement 2013: Sustainable and Efficient Pavements - Proceedings of the 2013 Airfield and Highway Pavement Conference | Year: 2013

Serviceability is an indicator that represents the level of service a pavement provides to the users. This subjective opinion is closely related to objective aspects, which can be measured on the pavement's surface. Modelling the present serviceability index is very important in pavement management systems. In the present study, the present serviceability index (PSI) has been analyzed using artificial neural networks (ANN) for the flexible pavements of urban roads. The study area considered constitutes 21 urban road sections for Noida city in the NCR of New Delhi, capital of India. Field data collected include slope variance, rut depth, patches, cracking, and longitudinal cracking for two consecutive years on the selected road network. The developed ANN model was also compared with a model developed using multilinear regression analysis. © 2013 American Society of Civil Engineers. Source


Kumar R.,University of Wisconsin - Milwaukee | Kumar R.,Central Road Research Institute CRRI | Naik T.R.,Center for By Products Utilisation
Indian Concrete Journal | Year: 2014

Manufacturing of greener concrete requires judicious use of natural resources and lower environmental impact in comparison with conventional concrete. This is generally achieved through reduced mining of natural resources required for manufacture of a concrete. tire derived fuel (TDF) is popular as the energy provided by the burning of tires is comparable to that of oil and greater than that of coal. tires are low in sulfur and have low NOx gas emissions, and can produce a cleaner ash than coal. In addition, end users can often get tires at a lower price compared to other fuels, making it a very cost effective option. By utilizing cement kilns controlled combustion environment scraped tire are being used as environmentally sound source of energy for the manufacturing of cement. tire rubber is ground to a particulate form termed as crumb rubber modifier (CRM) because its inclusion modifies properties of the asphaltic material. Source

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