Effects of wettability on the film-forming property of modified cement paste

• The influence of the wettability of modified cement pastes on the film-forming property was investigated. • The modified cement paste was redistributed during the film formation process. • The reduction of wettability can improve the adhesion ability between cement paste and aggregate in wet environment. The film-forming property of cement paste is an important factor affecting the compressive strength and water permeability of permeable concrete. In this paper, the influence of the wettability on the film-forming property of stearic acid modified cement paste was investigated by using surface free energy theory and film-forming experiments. The results show that the wettability of the cement paste decreased with the addition of stearic acid. The decrease of the wettability caused the formation of a hydrophobic film on the surface of the cement paste. It is found that the hydrophobic film caused the redistribution of the cement paste. The change of cement paste wettability has a strong impact on the formation of cement paste film on the surface of aggregate other than the surface of plastic rods. In addition, the reduced wettability of the cement paste improved the adhesion energy between cement paste and aggregate in wet environment. It is expected that the proposed method may pave a new way for preparing cement-based materials with good film-forming property by varying its wettability.