Evaluating Sustainable Colored Mortars Reinforced with Fly Ash: A Comprehensive Study on Physical and Mechanical Properties under High-Temperature Exposure

Abstract

This research primarily delves into a comprehensive investigation concerning the synergistic effects of fly ash (FA) with yellow pigment (YP) and red pigment (RP) in the workability, physical characteristics, and mechanical properties of colored mortars, both pre-and post-exposure to high temperatures. Within the experimental design, FA was employed as a 20% substitute for cement, while YP and RP were systematically incorporated into the cement mixtures at varying concentrations (1%, 3%, and 5% by weight). The specimens underwent controlled exposure to high temperatures, ranging from 300 °C to 800 °C. This study’s outcomes unveiled that while the introduction of FA positively influenced mortar workability, including YP and RP adversely impacted spreading diameters (SD), resulting in a discernible reduction in overall workability. Despite these effects, FA emerged as a pivotal factor to enhancing the residual compressive strength (RCS) and residual flexural strength (RFS) of the colored mortars. For instance, after 90 days at 800 °C, the control concrete (R0) exhibited a notable 66.13% decrease in RCS, and the sample solely incorporating FA (R1) demonstrated a reduced reduction of 55.39%. Similarly, mortars with YP additives (R2–R4) and RP additives (R5–R7) showcased RCS reductions within the range of 53.32% to 55.12% and 54.51% to 56.04%, respectively.