Caracterização e aplicação da cinza da casca de arroz visando o melhoramento da resistência mecânica no concreto autoadensável.

Abstract

CAA concrete stands out for its essential characteristics: form-filling capacity, passing ability and resistance to segregation, thus allowing for an increase in the quality of structural concrete pieces, as well as optimizing their execution. Rice husk ash (RHA) is an agricultural waste whose use as a mineral addition in concrete production has been widely studied characterization and application of rice husk ash aimed at improving mechanical strength in self-compensating concrete. The following techniques were used to characterize the resulting material: X-ray fluorescence (XRF) and X-ray diffraction (XRD). The results obtained showed that rice husk ash has pozzolanic characteristics, which allows it to be used in the manufacture of SCC. In order to evaluate this use, this study proposed a series of tests which were carried out on cylindrical specimens (10x20cm) with 5%, 10% and 15% cement substitution by mass, as well as a reference specimen with no substitution. The tests sought to evaluate the behavior of the concrete in its fresh state and in its hardened state, with the partial replacement of cement by CCA. The results showed that the characterization of the fresh-state FAC, conducted in accordance with the requirements of ABNT NBR 15823:2017, revealed the positive influence of CCA on the mixtures, which met the criteria established by the normative document. Compared to the reference concrete, the SCCs with the incorporation of pozzolan remained with adequate filling capacity and passing ability. As for the mechanical behavior, which was also verified by Brazilian standards, the presence of silica again caused changes compared to the control SCC. Thus, the data showed the technical feasibility of replacing cement with CCA, especially at 5% and 10%. The CAA produced in this study can be used in structures with a high reinforcement ratio, in parts that are difficult to access and, in the recovery, and repair of structures.