Sodium Oleate and Styrene-Acrylate Copolymer Emulsion-Modified Cement Mortar: Functional Combination of Physical Barrier and Hydrophobicity

Abstract

Styrene-acrylic emulsion (SAE)-modified mortar is typically used as an impermeable cement-based material. Although high-volume SAE-modified mortar shows excellent penetration resistance performance, this property can also cause compressive strength loss. In this work, sodium oleate (SO) is used as a hydrophobic agent to enhance the antipermeability of mortar with low SAE content. The influence of the incorporation of hydrophobic agent on the mechanical properties, hydration characteristics, water absorption, and impermeable and hydrophobic properties of low content polymer emulsion-modified cement mortars was investigated. The results show that the mortar with 5% SAE and 1% SO has better impermeability, hydrophobicity, and compressive strength than a mortar with 15% SAE only, which is attributed to the physical barrier of SAE and the hydrophobicity of SO. SO works well with 5% SAE-modified mortar, and the improvements in all aspects of the performance are greater than that of the high content SAE-SO–modified mortars. However, increasing the amount of SO will not bring continuous improvement in antipermeability, as the air-entraining effects of SO increase the porosity of the matrix.