Abstract
Ready-mix mortar is a ready-to-use mix containing air-entrained admixture (AEA) and hydration stabilising admixture (HSA) in its composition in order to increase workability and application time by up to 72 hours. This study evaluated the action of these admixtures in Portland cement pastes, employed both alone and in combination, isolating the aggregate’s effect.The properties of viscosity, specific gravity, entrained air and setting time were assessed in the fresh state. In the hardened state, capillarity, specific gravity and mechanical strength were evaluated. The results demonstrated interference and cross action between the admixtures, showing that HSA can also incorporate air into the paste and that AEA can delay setting time. Viscosity proved to be related to the stability of incorporated bubbles, but not to air content. The AEH provided greater capillary water flow, unlike the AIA. The mechanical strength of high content hydration stabilising admixture pastes decreased sharply, indicating possible delay in the formation of hydrated compounds. The intermediate AEH contents show to be more suitable for ready mix cement, which can be associated with higher AIA contents, without compromising its properties.
Keywords:
Hydration stabilising admixture; Air-entrained admixture; Portland cement paste.
