Long-term performance and hydration of cement mortars with hydroxyethyl methyl cellulose cured at 5℃ low temperature

•HEMC has a content inflection point of 1% for the mid-late flexural and compressive strengths.•HEMC has an optimal content range of 0.3–0.5% for tensile bond strength at 5℃.•Incorporating HEMC shows the limited effect on the final hydration degree at 5℃.•Incorporating HEMC significantly increases macro pores and total porosity. As one of the special curing regimes, low temperature environment is considered to be crucial to the development of various properties of cementitious materials. This work focuses on the long-term performance and hydration of cement mortars with hydroxyethyl methyl cellulose (HEMC) cured at 5℃. The results show that the mid-late flexural and compressive strengths decrease with the HEMC content increasing, to get the lowest values at 1% HEMC. Afterwards, with the HEMC content increasing to 3%, the above strengths gradually increase, still being lower than those of the control. The tensile bond strength increases with the HEMC content increasing, to reach the maximum value at 0.3–0.5% HEMC, and then decreases with the HEMC content increasing to 3%, which is still much higher than that of the control. The drying shrinkage presents a significant increase with the HEMC content increasing. Moreover, HEMC significantly retards the early hydration of cement pastes. But the final hydration degree of cement pastes with HEMC tends to be close to that of the control. In addition, macro pores and the total porosity increase with the HEMC content increasing at 0–1%, and then decrease to some extent at 3% HEMC. Obviously, due to its better long-term properties at 5℃, the cement mortars with HEMC are still applicable at low temperatures.