Research on the performance of composite cementitious materials under low temperature conditions

CHEN Yanwen; WANG Yunfeng; ZHANG Qiang

doi:10.3969/j.issn.1001-702X.2025.06.005

Abstract：Selecting ultrafine powder with a mass ratio of 1∶1 between fly ash and finely ground mineral powder to replace some cement,comparing the mechanical properties,pore size distribution,and hydration heat characteristics of composite cement-based materials under different curing temperatures and curing methods,and combining microscopic analysis to study the effect of ultrafine powder substitution rate on the properties of composite cement-based materials under low temperature conditions.The re-sults show that the compressive and flexural strength of mortar decreases with the decrease of curing temperature.When the re-placement rate of ultrafine powder is 20%,the compressive strength of the composite cement-based material cured at-10℃for 28 days increased by 10.6%compared to the blank group.After 3 and 7 days of low-temperature curing and 28 days of standard curing,the composite cement-based materials with blank group and ultrafine powder replacement rate of 20%have higher flexural and compressive strength.The addition of ultrafine powder can inhibit early hydration reaction of cement,reduce accumulated heat release,and the hydrated calcium silicate produced by secondary hydration can effectively fill the internal pores of cement,and im-prove the compactness of mortar.However,low temperature inhibits its activity.Under the same curing method,the average pore size of the mortar increases with the decrease of the curing temperature.