Combined use of reinforced perlite and vermiculite aggregates in lightweight mortar production

Perlite and vermiculite are natural materials of volcanic origin that are lightweight and have high insulation capacity. Their expanded forms are widely used in the construction, agriculture, and industrial sectors. However, the high water absorption rate and low mechanical strength of these aggregates limit their use, particularly in the construction sector, and prevent them from performing adequately on their own. In this study, the surfaces of expanded perlite and vermiculite aggregates were reinforced using a multi-layered coating method containing cement and silica fume, and a total of 25 different lightweight mortar designs were developed. Uncoated and reinforced aggregates with thicknesses of 1 mm, 2 mm, and 3 mm were substituted for cement-based mixtures at ratios of 0%, 25%, and 50%. The water-to-cement ratio was kept constant at 0.45 in all mixtures. Within the scope of the experimental studies, 50×50×50 mm cubes and 40×40×160 mm prismatic samples were prepared, and the fresh mortar properties were evaluated using the spread plate test. The performance of the hardened mortar was analyzed through water absorption, unit volume weight, sorptivity, compressive strength, flexural strength, and thermal conductivity tests. The findings indicate that the coating significantly improves the physical and mechanical properties of the aggregates. Compared to mortars prepared with 50% uncoated aggregates, mortars obtained with multi-layered aggregates showed a 740% increase in compressive strength, a 107% increase in flexural strength, and a 61.78% decrease in water absorption. These results demonstrate that reinforced aggregates simultaneously offer high strength and low permeability, enabling the production of lightweight and durable construction materials; thereby highlighting the potential for more efficient utilization of domestic resources such as perlite and vermiculite in the construction industry.