Internal curing of mortar with low water to cementitious materials ratio using a normal weight porous aggregate

• A normal weight porous aggregate, with SSD density of 2.3 g/cm3, was prepared.
• Normal weight porous aggregate absorb water faster than expanded clay.
• Normal weight porous aggregate increase the compressive strength of mortar.
• Normal weight porous aggregate could effectively diminish the shrinkage of mortar.
• Normal weight porous aggregate reduce the heterogeneity of mortar after vibration.

A normal weight porous aggregate (NWPA), with the saturated surface dry density of 2.3 g/cm3, was prepared. Impact of NWPA on performance of mortar with water to cementitious materials ratio of 0.3 was presented in this paper. The results show that NWPA has smaller pores and higher water absorption speed than expanded clay, but lower desorption speed. Strength of mortar accompanying NWPA is higher than or close to that of a plain one. Mortar containing NWPA expand less than that with expanded clay under sealed condition, which suggests the lower internal curing efficiency of NWPA. However, still it could diminish the shrinkage of low w/c mortar and be used as internal curing agent. Variation of water absorption and dynamic modulus from top to bottom of mortar with NWPA is similar to that of plain one, and lower than that of expanded clay mortar, which certifies that NWPA could promote the uniformity of internally cured mortar.