Effect of Alkaline Environment on the Behavior of High-Density and Low-Density Concrete

Abstract

Concretes that are exposed to high alkalinity suffer from strength deterioration, leading to the requirement for designing new concretes with enhanced durability. In this paper, a comparison study has been done for the mechanical properties and durability of high-density concrete (HDC) and low-density concrete (LDC) subjected to the same alkaline curing conditions (pH = 13). The HDC was prepared by using aggregates of barite and haematite, whereas the LDC was prepared by using aggregates of pumice and vermiculite, with the M60 conventional concrete used as a control. The mechanical and durability properties were tested by using compressive strength, split tensile strength, flexural strength, and the Rapid Chloride Penetration Test (RCPT). The alkaline curing decreased the compressive strength of barite, haematite, pumice, vermiculite, and conventional concrete by 2.80%, 3.99%, 11.30%, 10.60%, and 5.60%, respectively. Similar reductions were found in the split tensile strength (2.80–8.90%) and flexural strength (0.93–12.41%). Results from the RCPT test revealed that barite concrete had the least chloride permeability (999 Coulombs), followed by haematite concrete (1126 Coulombs), regular concrete (2284 Coulombs), and vermiculite concrete (3247 Coulombs). It is clear from the results that barite-based high-density concrete is more durable in aggressive alkaline environments and therefore a good choice for such industrial constructions.