Avaliação da resistência de aderência ao cisalhamento de prismas de tijolos cerâmicos maciços moldados com argamassa “eco-friendly” com adição de fibras de polipropileno

Abstract

This work aimed to evaluate the bond strength through shear testing with precompression according to BS EN 1052-3 (2002) and the cracking and breaking process of the mortar/brick interface, by image correlation in GOM Correlate® software on prisms of solid ceramic bricks produced with mortars with 0 and 5% partial replacement by mass of Portland cement by silica fume from rice husk added to 0.3 and 0.5% polypropylene fibers by volume of mortar when applied at different time intervals (15, 60 and 120 min). These mixtures were also evaluated for threepoint bending tensile strength and axial compressive strength according to ABNT NBR 13279 (2003). In the results found for the mechanical behavior, the mortar mixture with 0% partial replacement and incorporation of 0.3% polypropylene fibers was the mixture that presented the highest average maximum stress. It was 3.28 MPa for tensile strength in bending at three points, presenting no significant difference only in relation to the mixture with 5% partial replacement of Portland cement by rice husk silica and incorporation of 0.5% polypropylene fibers. And 10.90 MPa for axial compressive strength, pointing out significant difference with all analyzed mixtures. Regarding the shear tests with pre-compression of solid brick prisms, the performance of mortar mixtures in most cases did not show significant differences. Regarding the application of mortar mixtures, only the mixture added with 0.5% polypropylene fibers was not recommended to be applied in all time intervals studied. However, when evaluating the mode of cracking and rupture of the mortar/brick interface, it was possible to observe that the mixtures containing polypropylene fibers and partial replacement of Portland cement by rice husk silica showed improvement in their performance, promoting the displacements of the laying joints equal in most of the time of the tests and the behavior in an equivalent and uniform manner in the distribution of stresses in relation to the reference mixture. Keywords: Mortars; Adhesion strength; Shear strength of prisms; Polypropylene microfibers; Partial replacement of Portland cement.