A performance analysis of conventional reinforcement methods for “exotic” building stones according to the current technical requirements

Standard methods for dimensioning stone applications have increased their importance in new construction projects. Natural stones are unique in their structure, and thus, one would expect larger differences in properties when compared with other synthetic competitors. To pursue the objective of meeting technical requirements, very heterogeneous stone slabs (such as exotic materials with high market value) are usually reinforced using epoxy resins embedded in low-density glassfiber, a process showing low mechanical efficiency. In the present work, four types of thermoset resins and two types of glass fibers were used to reinforce a pegmatitic stone from Brazil, in order to determine the flexural strength and compare it to a sound sample. Results after 4-point bending tests show that relative stiffness is not affected by the use of glassfiber solutions, and the standard dimensioning requirements are only attained in accordance to mechanical strength when high-density glassfiber systems are employed in the surfaces submitted to tensile stresses under a flexural loading. This work allows concluding that, when using such exotic and highly heterogeneous stones, conventional reinforcement methods are not adequate, especially for more demanding cladding and flooring applications.