Avaliação de propriedades físicas e mecânicas em concretos produzidos com materiais da cidade de Manaus com o uso de redutores de permeabilidade por cristalização

Abstract

The durability of concrete structures has become one of the main concerns of the construction industry, especially after ABNT NBR 15.575: Housing Buildings - Performance comes into force. One of the major bottlenecks of concrete structures is their low resistance to cracking, which jeopardizes their durability, in addition to allowing liquids and aggressive agents to penetrate the matrix and cause damage. These cracks can have their dimensions increased and expose the reinforcement to aggressive environments and consequently lead to structural collapse. Thus, constant inspection, maintenance and repairs to the structures are essential. However, these repairs are often costly and difficult to perform. The self-healing of concrete cracks has gained notoriety as an alternative to these factors, which consists of a phenomenon whose concrete itself has the ability to repair small cracks spontaneously, without any external intervention. The objective of this study is to evaluate the effects of the ADDITIVE REDUCING POROSITY BY CRYSTALLIZATION - ARPC on the durability of concretes produced with materials from the city of Manaus, through experimental research, analyzing the autogenous healing. Four concretes were produced with a fixed water / cement ratio of 0.58, addition of ARPC and cement, CPII Z-40-RS and CP II E-32 were used. In these concretes, the properties of compressive strength at 28 days under 100% and 90% rupture load were analyzed for the induction of micro-cracks in concretes and subsequent evaluation of healing at 84 days by means of compressive strength. The properties of voids index, total absorption, capillarity absorption, chloride ion migration and concrete microstructure were also evaluated. As a result, it was found that ARPC performs better in concretes produced with CP II Z-40 RS, mainly at the age of 84 days. In addition, concretes with the addition of ARPC present better performance in the percentage of recovery of compressive strength. In the voids and total absorption indices, the concrete with ARPC and CP II Z-40 RS presented the lowest values. In capillarity absorption, concretes with the addition of ARPC showed lower absorption rates and lower capillary rise. The microstructure showed typical crystals of self-healing concrete such as etringite and calcium carbonate. In the migration of chloride ions, the concretes produced with CP II E-32 showed the lowest concentrations, which is due to the fact of the cement composition with the presence of blast furnace slag.