Influence and effectiveness of water-repellent admixtures on pozzolana–lime mortars for restoration application

Pozzolana–lime mortars modified with water-repellent admixtures were designed and studied to obtain mortars for restoration application. Powdered silane and calcium stearates were mixed with pozzolana, lime and sand and the chemical–physical properties of the resulting mortars were evaluated by X-ray diffraction, electron microscopy (SEM-EDX), thermogravimetric analysis and FT-IR spectroscopy. The mechanical behavior, the pore structure and the hygric behavior were measured. The resistance of water-repellent mortars to the salt crystallization was evaluated. Both calcium stearates and powdered silane allowed good water-repellent protection even if the water-repellent agents and their dosage modified some physical properties and the hydration kinetic.