Producing a gypsum-based self-leveling mortar for subfloor modified by polycarboxylate admixture (PCE)

Abstract

Self-leveling mortar is a layer applied on a surface without the need for thickening. This type of mortar has large fluidity and is often cement-based, with low productivity. The production of a self-leveling gypsum-based mortar provides shorter execution times, as well as better thermal and acoustic properties and eliminates the need for expansion joints in large areas. This article aims to develop a gypsum-based mortar with self-leveling properties for application in the subfloor layer. In this sense, water/gypsum ratios of 0.45, 0.475, and 0.5 were used, in addition to plaster/sand ratios of 1:1 and 1:0.5 for each consistency. The content of superplasticizer additive (PCE) was adjusted to consistency suitable for self-leveling through the fluidity test. The set of mortars were characterized by considering tests of fluidity, enthalpy of hydration, setting times, compressive and flexural strength, and experiments of scanning electron microscopy (SEM). The results revealed that the PCE increased the setting times, reduced the water content, and modified the crystalline structure of the dihydrate. Finally, the mortar with water/gypsum ratio of 0.5, gypsum/sand ratio 1: 0.5 and 1% PCE presented satisfactory properties, with the exception of setting times.