Effect of Sulfoaluminate Expansive Additives on Early-age Creep and Internal Relative Humidity of Cement Mortar

The addition of sulfoaluminate expansive additives(SEA)can reduce the shrinkage of cementitious materials,however,the effect of SEA on materials’creep and internal relative humidity is still unclear,which is not conducive to the accurate crack assessment of concrete structures. This work conducted an experimental study on the early-age creep,internal humidity,and pore information of cement mortars with 0%, 4%,and 8% SEA,and a simulative analysis about the effects of porosity and pore size on the creep property based on a finite element model with randomly-distributed pores. The results show that the mortar creep changes inversely with the increasing SEA content,and the reduction effect of SEA on the creep property of mortar loaded at a later age is more significant. There can also be found an inverse variation of internal relative humidity with increasing SEA content. SEA addition can reduce the porosity of cement mortar and refine the pore size. A 1% increment in mortar porosity results in 4% rise of creep,while the refinement of pore size has a limited effect on reduction of creep. The effect of SEA addition on mortar’s creep reduction can be attributed to the decreases in calcium silicate hydrate,internal relative humidity,and porosity,as well as the refinement of pore size. © 2025 Cailiao Daobaoshe/ Materials Review. All rights reserved.