The Effects of Curing Temperature on CH-Based Fly Ash Composites

Abstract

Curing temperature affects the compressive strength of cement paste systems via the pozzolanic reaction. However, different processes, climates, and weather conditions often result in different initial curing temperatures. The relationship between curing temperature and compressive strength is still an underexplored domain. To explore the effect of curing temperature on calcium hydroxide (CH)-based fly ash composites, fly ashes from different carbon sources were used to make CH-based composites, and the compressive strength, reaction rate, CH content, and C-S-H generation were analyzed. The correlation between the reaction rate and C-S-H content was analyzed. High-temperature curing improved the compressive strength of the cement paste system by affecting the CH-based reaction rate in the initial stage, with the highest initial reaction rate reaching 28.29%. However, after cooling to constant temperature, high-temperature curing leads to a decrease in CH and C-S-H content. The average decrease rate of calcium hydroxide content under high temperature curing is 38%, which is about 2.38 times that of room-temperature curing conditions. This led to a decrease in the compressive strength of the cement paste. Therefore, the performance of CH-based fly ash composites produced by low-temperature curing was superior to that of composites produced by high-temperature curing.

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

“…The primary phases in all samples under ambient conditions were identified as portlandite (CH), calcium-silicate-hydrate (C-S-H), and quartz (Q) [64,65]. However, distinct from the R0 control sample, the FA-doped R1, R4, and R7 samples exhibited crystal phases of calcite (CaCO 3 ) and mullite (Al 6 Si 2 O 13 ) in addition to these primary phases [66,67]. Further, the YP and RP-doped R4 and R7 samples showcased crystal phases of goethite (FeOOH) and hematite (Fe 2 O 3 ), respectively, alongside the earlier mentioned phases [68,69].…”