The effect of curing methods on the mechanical and microscopic properties of ultrahigh-performance concrete (UHPC) was investigated at different curing temperatures (i.e., 20, 40, 60, and 90 ℃) and with thermal insulation. The results show that the compressive strength of UHPC is positively correlated to the early curing temperature, but the difference decreases with the age. The 28 d compressive strength difference of UHPC is less than 4%, and the tensile strength is high after curing with thermal insulation or at 90 ℃ in early stage. The peak value of heat flow of each samples increases with the increase of the ambient temperature and occurs in advance, and the cumulative heat release becomes stable in a shorter time. At 4 d, the intensity of Ca (OH)₂ diffraction peak in UHPC matrix after curing with thermal insulation is reduced, compared to that after curing at 20 ℃, indicating that the admixture is well involved in the hydration. The mean chain length of Si-O chain in the C-S-H gel for UHPC after curing with thermal insulation in early age is similar to that for the samples after curing at 90 ℃, and the matrix density is extremely high.

ultrahigh-performance concrete  /  early-age curing  /  thermal insulation  /  mechanical properties  /  microstructure