MECHANICAL PROPERTIES OF CONCRETE WITH TYPE F FLY ASH ADDITION UNDER ACIDIC CONDITIONS

Abstract

Concrete is a fundamental construction material whose performance can be significantly improved through the incorporation of supplementary cementitious materials such as fly ash, a by-product of coal combustion. This study examines the effects of replacing 20% of cement with Type F fly ash on the mechanical properties of concrete exposed to acidic mine water over varying curing periods (28, 42, 56, and 86 days). A total of 33 cylindrical specimens (150 mm in diameter and 300 mm in height) were prepared and immersed in acidic mine water to simulate aggressive environmental conditions. The results showed that concrete with 20% fly ash reached a compressive strength of 24.67 MPa at 28 days, then increased to 26.37 MPa at 42 days, and subsequently declined at later ages. In contrast, the split tensile strength consistently increased, peaking at 2.89 MPa at 56 days. The incorporation of Type F fly ash was proven to improve the mechanical resistance of concrete under acidic exposure by reducing the detrimental effects of acid attack. These findings indicate that fly ash-modified concrete exhibits superior mechanical performance and acid resistance, with the optimal curing period observed at 42 days.