Effect of Curing Temperature on Mechanical Strength and Thermal Properties of Hydraulic Limestone Powder Concrete

In this study, the effect of curing temperature on mechanical strength and thermal properties of hydraulic limestone powder (LS) concrete is investigated. The hydration products and microstructure of hydraulic LS concrete are characterized through X-ray diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). The results indicate that the mechanical strength decreases with an increase in the LS dosage. The largest mechanical strength at 3 and 7 d is recorded at the curing temperature of 50 degrees C, that at 28 and 90 d is obtained at 20 degrees C, whereas the lowest mechanical strength from 3 to 90 d is obtained at 5 degrees C. The thermal conductivity and thermal diffusivity of LS concrete are positively correlated with the compressive strength. The adiabatic temperature rise decreases with an increase in the LS dosage, and the largest temperature rise is obtained at the initial temperature of 5 degrees C, followed by those obtained at 20 and 50 degrees C. The longest fibrous C-S-H and thickest plate Ca(OH)2 with the largest size at 90 d is obtained at a curing temperature of 50 degrees C, followed by those obtained at 20 and 5 degrees C. The MIP results indicate that the largest total amount of gel pores and medium capillary pores at 90 d are obtained at a curing temperature of 20 degrees C, followed by 50 and 5 degrees C.