Effects of substitution of cement with ground granulated slag on concrete produced with different water-cement ratios

Abstract

Due to growing concerns on the need for alternative material to partially replace cement considering the high cost and environmental problems associated with its production, this study investigated the impacts of fractionalsubstitution of cement with ground granulated steel slag (GGSS) onthefeatures of concrete produced by varying water-cement ratios (w/c). Cement was replaced with GGSS at 0, 10, 20, 30, 40, and 50%. The binder, sandandgranite ratio of 1:2:4 as well as the w/c of 0.3, 0.4, 0.5, 0.6, and 0.7wereused.The X-ray fluorescence (XRF) analyser was utilized to ascertain the chemical composition of the GGSS, and its result revealed that GGSS is aclass FPozzolan. The fresh and hardened concretes containing various levelsofreplacement of cement with GGSS under varying w/c were subjected to workability and various strength tests. Response Surface Method(RSM) was employed for optimum condition analysis that maximized the results of the Compressive Strength (CS), Split Tensile Strength (STS) and Flexural Strength(FS) tests. Findings revealed that concrete becomes more workable with increasing w/c, but declined as the substitution of cement with GGSS increased. The strengths of the concrete declined with increasing w/c; however, the addition of GGSS improved its strength’s properties. The optimized 21.57%GGSS substitution for cement with w/c of 0.45 gave maximum value of 25.95N/mm² for CS, 4.24 N/mm² for STS and 5.74 N/mm² for FS. The  comparative cost analysis between the conventional concrete and the optimized OPC-GGSS concrete shows that as much as 11.2% of the  concrete constituents’ cost canbesaved if GGSS is used to substitute OPC in the concrete production. Theoptimized concrete, which can  be utilized as reinforced concrete withimprovedstrength and reduced cost, is therefore recommended for use with the target CSof 25 N/ mm².