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.