Enhancing water resistance of plaster mortar with cement additives

Global research on waterproofing admixtures has progressed significantly over decades, driven by the need to enhance structural durability against water-induced degradation. In Vietnam, such investigations are particularly relevant due to the challenges posed by tropical monsoon climates on building integrity. This study evaluates the effect of cement-based waterproofing additive dosage (0–20% by weight) on cement–sand mortar performance. Experimental testing of compressive strength and water permeability revealed that additive incorporation up to 10% improves both mechanical properties and water resistance. Beyond this threshold, waterproofing efficiency declines, with some mixtures exhibiting inferior performance to additive-free controls. The findings emphasize the necessity of optimal additive dosage to maintain equilibrium between mechanical strength and water resistance in construction applications.