Characterization of Structural Mortars Reinforced with Sisal Fibre, Recycled Rubber and Expanded Vermiculite

The construction of cisterns — reservoirs specifically designed for the collection, storage, and conservation of water — has emerged as a significant strategy for mitigating water scarcity in arid regions. A widely adopted form of cistern construction involves the use of cementitious composite panels. This study investigates the mechanical properties of cementitious composites incorporating rubber waste, expanded vermiculite, and sisal fibres. Three distinct mortar formulations were developed and evaluated in terms of water absorption, voids index, specific mass, compressive strength, flexural tensile strength, dynamic modulus of elasticity, and damping factor. Relative to the reference mixture, the incorporation of sisal fibres (SF) in conjunction with rubber and vermiculite resulted in a 12–16% reduction in density, a 29.5–30.4% decrease in the dynamic modulus of elasticity, and a 2.5–9.0% increase in the damping factor. Despite an observed reduction of approximately 40% in compressive strength, the values remained within the acceptable range for structural applications. These findings substantiate the technical viability and environmental benefits of the proposed mortars for the sustainable construction of cisterns.