Estudo das propriedades mecânicas e físicas de um traço comercial de concreto autoadensável com e sem substituição de cinza de casca de arroz

Abstract

In this work the physical, mechanical, acoustic and thermal properties of a Self-consolidating concrete (SCC) mix design already used by a concrete plant and others three mix design with Portland cement (PC) replacement by Rice husk ash (RHA) were studied. The reference mix design (without replacement) was used in the construction of a concrete wall building. The experimental tests were defined in order to allow the analysis of both the compressive strength and diametral tensile strength, as well as the thermal and acoustic comfort presented by this material, Thus, the tests were realized in the fresh state, guaranteeing the specifications of all properties required for a concrete to be considered self-consolidating. After this characterization, the necessary specimens were molded for all the hardened state tests, being cylindrical specimens (100x200mm) for mechanical tests, cylindrical (20x100mm) for acoustic tests and rectangular (300x300x100mm) for thermal tests. The compressive strength exceeded the fck established at 28 days, which was 25 MPa. Analyzing the values found for absorption and acoustic insulation, it can be said that they presented satisfactory results in the lower frequency range and, in the higher, presented some problems that are believed to be referring to the equipment used. In the thermal performance, all the mix design present close results among themselves and other studies of the bibliography and norms, not being influenced by replacement of the RHA. The tests results demonstrated that it is possible to replacement PC for RHA without impairing the mechanical features of the SCCs as well as to obtain economic gains. The best concrete, taking into account all aspects studied, was with a 20% replacement of PC for RHA.