Effect of hydrophobization treatment on the hydration of repair Roman cement mortars

Hydrophobization agents are commonly used in conservation practice to enhance the water-repellent properties of stone and masonry structures such as bricks and restoration mortars. In this project, we have tested and analyzed the effects of various commercially-used water repellents on the hydration process of Roman cement mortars. The necessity to investigate the progress of hydration of these materials in the presence of water-proofing agents arises from the well known fact that Roman cement mortars require adequate times and conditions for curing, which gives the restoration material compatibility with the original substrates. The effects of hydrophobic treatment on the pore size distribution and some physical features, such as water absorption and capillary rise, were investigated on Roman cement mortars treated with polymer-based coatings and inner waterproofing agents. The behavior of mortars in terms of their freeze resistance was also evaluated. The surface treatment using a hydrophobization agent completely prevented water absorption and thereby interrupted the hydration process. In the case of inner water-repellent admixtures, the hydration process progressed in spite of the decrease in water capillary transportation. In such circumstances, unimodal distribution of pore sizes was observed along with a decrease in threshold pore width with increased curing time.