Effect of Accelerated Curing and Normal Curing Regimes on UFGGBFS-Based Semi-Lightweight Concrete

Abstract

This paper deals with the performance of semi-lightweight concrete (sLWC), prepared by using calcite powder pellets as coarse aggregates which was improved by partial replacement of cement with UFGGBFS (ultrafine ground granulated blast-furnace slag). Cement could be replaced by UFGGBFS as 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, and 70% to enhance the strength and durability properties of concrete. High-range water-reducing admixtures (HRWA) were used in these mixes which were dosed up to 1.5% weight of the total cementitious material content. It also develops the weaker transition zone into more impermeable layers. Specimens were subjected to accelerated curing (AC) method as well as conventional curing method. Experimental results were compared and reported that a maximum 28th-day compressive strength of 32.6 MPa has achieved at 30% replacement level with a density of 2200 kg/m3 in conventional curing, while in AC, the maximum compressive strength of 29.5 MPa has achieved at 40% replacement level. From the experimental results, the conventional curing method shows the better compressive strength when compared with the AC method. Therefore, rapid chloride penetration test (RCPT) was conducted on conventional cured specimens. The RCPT test results show that the replacement level at 70% gives the charge passed of 545.6 coulombs which comes under “very low” category of penetration of chloride ions when compared with 0% replacement level of 3296.7 coulombs which comes under “high” category. From the test results, it was concluded that the increase of UFGGBFS percentage improves the resistance of sLWC against aggressive chloride ions.