Surface and bulk hydrophobic cement composites by tyre rubber addition

Rubber addition increases porosity, nevertheless it can hinder liquid water entrance. Abstract Penetration of water in cement composites, porous and hydrophilic materials, is cause of progressive deterioration and failure. Standard procedures for protecting building structures generally involve uniquely the modification of the surface by coating or impregnation procedures. In this work, the addition of tyre rubber (TR) to the cement paste is demonstrated to be effective for developing mortars with a pronounced hydrophobic behavior in every part of their structure. Hydrophobic performances are better in the case of finer TR grains size and for larger TR volume addition. TR mortars show higher porosity than the conventional ones, nevertheless the effect of the low rubber surface energy prevails, and the absorption of water drops is almost completely abated. These lightweight materials result to be very competitive for non-structural applications and are in agreement with the environmentally sustainable policies finalized to convert a synthetic waste to an engineering resource