Effects of post-fire curing conditions on the restoration of material properties of fire-damaged concrete

•Post-fire curing effects on increasing mass of fire-damaged concrete.•Contact-type defects could be recovered by some post-fire curing conditions.•Material properties of fire-damaged concrete were recovered at higher humidity. Under specific post-fire curing conditions, concrete regains its material properties along with the recovery of contact-type defects. An experimental study was carried out to investigate the effects of post-fire curing conditions on fire-damaged concrete. After exposing concrete specimens to three different high temperatures ranging from 300°C to 700°C, fire-damaged concrete specimens were stored in a thermo-hygrostat with 12 different post-fire-curing conditions, which were varied by the relative humidity condition and the curing time. The degree of fire damage can be estimated through an evaluation of the tensile strength and the nonlinearity parameter, which can sensitively reflect the contact-type defects in concrete. These components were measured by a splitting tensile test and the nonlinear resonance vibration method, respectively. The experimental and analytical results confirm that the recovery of material properties in fire-damaged concrete is closely related with the post-fire curing conditions, and finally this paper introduces the appropriate post-fire curing condition to restore the material properties of fire-damaged concrete.