Influence of Natural Perlite Fineness Variation on the Physico-Mechanical Properties of Mortars

This study investigates the influence of natural perlite fineness on the physical and mechanical properties of cement mortars. Natural perlite was ground for 2, 4, and 6 h, producing Blaine fineness values of 3040, 5900, and 8030 cm2/g, respectively. Standardized mortars were prepared by replacing 15% and 25% of the cement mass with perlite. The effects of perlite fineness were evaluated through superplasticizer dosage, semi-adiabatic calorimetry, and compressive strength at curing ages from 1 to 180 days, and water-accessible porosity at 180 days. The results showed that perlite fineness influenced the fresh and hardened properties of the mortars. Increasing fineness generally reduced the superplasticizer dosage required to achieve the target consistency. Perlite-containing mortars exhibited lower early heat release than the reference mortar, and increasing perlite fineness partially enhanced heat evolution. The finest perlite improved compressive-strength development and produced the lowest water-accessible porosity at both replacement levels, particularly at later ages. These findings demonstrate that natural perlite fineness is an important parameter influencing the physical and mechanical properties of mortars.