Abstract

Water repellents are widely applied directly to the outer surfaces of existing buildings to increase the hydrophobicity and durability of historic facades. Nevertheless, there is little control over the initial moisture content inside masonry and boundary conditions in practice. The fluctuating temperature and moisture content of a wall are inevitable when applying the treatment under natural climatic conditions, therefore the efficiency under realistic application approaches may not be as optimal as in the lab. This research aims to understand how application circumstances affect the hydrophobic efficiency of a siloxane-based water-repellent solvent on sandstone. Samples with different moisture content were treated and cured under different temperature to simulate various field climate conditions in practical applications. The experiments indicate that application temperature and relative humidity have little effect on water-repellent efficiency. The water-repellent product is also effective on saturated walls.