Evaluation of the Contact Angle of Hydrophobised Lightweight-Aggregate Concrete with Sewage Sludge

The aim of the research presented in the paper was to evaluate the feasibility of using hydrophobic preparations based on organosilicon compounds for protection treatment of lightweight aggregates modified with municipal sewage sludge. Issues related to the wettability of the surface layer of hydrophobised lightweight-aggregate concrete supplemented with sewage sludge are discussed in the paper. The experimental part of the study is focused on the physical and mechanical characteristics of lightweight-aggregate concrete and the effect of two hydrophobic preparations on the contact angle of the material. The contact angle for lightweight concrete (θ_w) was determined as a function of time using one measurement liquid. The hydrophobic coatings in the structure of lightweight concrete modified with sewage sludge were shown using electron microscopy. The investigations demonstrated the effectiveness of hydrophobisation of porous lightweight concretes. On the hydrophobic surfaces, the contact angles decreased with time and depended on the preparations used. The results of the research confirm the possibility to produce lightweight aggregate-concretes modified with sewage sludge with appropriate surface protection against external moisture.