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Pramodini Naik Gaonkar ¹

Affiliations
1 Government Polytechnic, Bicholim-403504, Goa, IN

Abstract

Concrete is the most commonly and widely used building material applied in all forms of construction, with an annual production exceeding 2 billion metric tons per year, it is the single most widely used manufactured substance on earth owing to its remarkable versatility as a building material. But the production of raw materials of concrete has certain detrimental effects on environment, mostly the production of cement and coarse aggregated obtained from crushing plants and continuous mining of river beds for getting the natural sand. Eight to 10 percent of the world's total CO2 emissions come from manufacturing cement. The global warming gas is released when limestone and clays are crushed and heated to high temperatures. Whereas production of granitic coarse aggregates on large scales and indiscriminate mining of river beds for sand, to overcome the demand of concrete raw materials has resulted in serious environmental and social problems. Therefore there is an urgent need to find alternative or green materials of concrete to preserve and protect our natural resources for future, by replacing them partially or fully to achieve sustainable development in construction industry. Green concrete is defined as a concrete which uses waste material as at least one of its components, or its production process does not lead to environmental destruction, or it has high performance and life cycle sustainability This paper mainly discusses the potential use of ground granulated blast furnace slag (GGBS), naturally available river pebbles, crushed rock fines (CRF) as partial replacements to cement, sand and coarse aggregates for making green concrete. This research evaluates the strength of hardened concrete, by partially replacing cement by various percentages of ground granulated blast furnace slag, natural sand by CRF and coarse aggregates by river pebbles for M40 grade of concrete at different ages. From this study, it can be concluded that, since the grain size of GGBS is less than that of ordinary Portland cement, its strength at early ages is low, but it continues to gain strength over a long period. The optimum use of green materials as replacement to cement, sand and coarse aggregates is characterized by high compressive strength and good workability.

Keywords

Green Concrete, Sustainable Concrete, GGBS, Crushed Rock Fines.

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Pramodini Naik Gaonkar ¹, Satish Annigeri ²

Affiliations
1 Government Polytechnic Maem, Bicholim, Goa, IN
2 B.V. Bhoomaraddi College of Engineering and Technology, Vidyanagar, Hubli, Karnataka, IN

Abstract

Reinforced concrete buildings represent major type of concrete structures all over the world. It is observed from the past major earthquakes in India, Turkey, China,Nepal and other countries, numerous medium to high rise buildings suffered major damages including life and safety of people. This clearly implies that the design capacity of buildings designed as per codes was not enough to withstand earthquake demand. In the regions of high seismic activity,safety of these buildings occupying major population is of growing concern, as most of them are seismically deficient, as many low to medium rise buildings are designed only for gravity loading, or they are designed for earthquake forces by performing elastic analysis. When elastic analysis is performed, building structure is assumed as a linear system.This analysis is sufficed to withstand mild earthquakes but a major earthquake is expected to cause significant structural damage resulting in loss of structural stiffness. A linear elastic analysis is not applicable in this situation since these analyses do not account for change in structural properties nor they give any idea about the location and extent of damage or in elasticity. The true response is therefore determined only by non-linear analysis considering the changing stiffness of the various members and moment distribution, when structures are subjected to moderate or major earthquakes. Thus to mitigate the effects of future earthquake damages, the seismic design should be carried out incorporating non-linear analyses to calculate structural response in order to assess and design seismic retrofit solutions for existing buildings and design new buildings based on above approach. In the present study three different building models are designed for critical load combinations by considering lateral Earthquake load by Equivalent Static Analysis (ESA) and Response spectrum analysis (RSA) and then pushover analysis is carried out to assess their performance. The performance of building models, displacements corresponding to performance point (PP), and hinging pattern at PP are presented and studied. It is concluded that ESA method of analysis has satisfactory performance and RSA method of analysis design exhibits over strength using pushover analysis method for evaluation.

Keywords

Pushover Analysis, Performance Point.

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