AN INVESTIGATION ON COMBINED REPLACEMENT OF CEMENT BY GGBS AND NATURAL SAND BY SLAG SAND ON STRENGTH OF CONCRETE

The utilization of waste materials from the industries has been continuously emphasized in the research work. The present work is to use GGBS (Ground Granulated Blast Furnace Slag) and Slag sand as combined replacement for ordinary Portland cement and river sand respectively. M20 grade of concrete with W/C 0.5 is carried out with two percentages of cement replacement by GGBS i.e, 35 % and 45%, along with this the slag sand is varied from 0 % to 100 % in step of 20%. In first variation, 35%GGBS is replaced by cement and slag sand is varied as 0%, 20%, 40%, 60%, 80 % and 100%. In second variation, 45 % GGBS is replaced with cement and slag sand is varied as 0%, 20%, 40%, 60%, 80%, and 100%. For all mixes compressive strength, split tensile and flexural strength are determined at different days of curing. The strength of cube specimens varied from 21.55N/mm to 33.61N/mm. The optimum strength of concrete Mix (30.19N/mm) having 35%GGBS and 60 % slag sand and strength of concrete Mix (33.16 N/mm) having 45 % GGBS and 40 % slag sand replacements was considered to cast reinforced concrete beams. The beams are tested for flexure, under two point loading condition. Different parameters were investigated