Influence of Surface Sealers on the Properties of Internally Cured Cement Mortars Containing Saturated Fine Lightweight Aggregate

Abstract

To date, internal curing (IC) has been widely accepted as a promising way to mitigate the autogenous shrinkage of high-performance concretes (HPCs). While extensive studies have confirmed the benefits of internal curing to HPCs cured under sufficient moisture, the durability implications of early-age drying remain unclear for internally cured cement-based materials. As such, this work investigates the influence of early-age drying on the properties of internally cured cement mortars containing saturated fine lightweight aggregate (LWA). The tests conducted on cement mortars with or without internal curing include: drying shrinkage, moisture loss, compressive strength, splitting tensile strength, water absorption, and gas permeability. Additionally, two surface sealers were individually applied to mortars and evaluated for their effectiveness in reducing the risk of early-age drying. The results reveal that early-age drying significantly offsets the advantages of internal curing of LWA with respect to shrinkage reduction and microstructure densification. In this case, the presence of surface treatments can preserve and enhance the benefits of internal curing of cement mortar. Observations made using a scanning electron microscope suggest that coverage and integrity of the sealer film define its effectiveness in retaining moisture. Further studies on concrete specimens with larger cross sections and with various curing conditions are recommended in order to practically evaluate the effect of early-age drying on internally cured concrete.