Desempenho estrutural de um protótipo edificado com blocos de gesso – pó de pedra e propriedades desse compósito

Abstract

Gypsum is one of the oldest building materials known. As it is a less aggressive binder to the environment than Portland cement, its use should be encouraged, and new applications studied. This work presents a technological innovation concerning new use of plaster in civil construction: in structural blocks for use in buildings. Thinking about the sustainability of the construction, stone dust is used as a partial replacement of gypsum, as it is a waste with excellent characteristics and little used in conventional constructions. Initially, the work addresses the physical and mechanical characteristics of the materials used. Then, emphasis is placed on the study of the composite (plaster/stone powder). Gypsum replacement contents from 0% to 50% with intervals of 10% and the water/gypsum ratio varying from 0.5 to 0.9 in intervals of 0.1 were used. The initial and final setting time, calorimetric curves, density, water absorption by immersion and by capillary, Shore hardness, resistance to compression and flexion were obtained for each mixture. Some images of the microstructure are presented, as well as the propagation velocity of the ultrasonic wave in some mixtures. Based on the results, the composite (plaster/stone powder), with a water/gypsum ratio equal to 0.6 and 40% replacement of gypsum by stone powder was chosen, for casting blocks to build a prototype taking into account the construction system already developed at the Federal University of Paraíba, which practically eliminates losses. The prototype was submitted to Brazilian Standard ABNT NBR 15.575 performance tests. Resistance to suspended loads, rigid body impact strength, soft body impact strength and behaviour under sudden door closing were obtained. The results indicate that the constructive system could be classified with superior performance level. Thus, it can be said that the work resulted in the approval of a new composite, block type and construction system for use in building masonry with minimization of losses and waste generation.