Análise das propriedades da matriz de concreto produzida com incorporação dos resíduos de blocos de alvenaria estrutural

Abstract

The construction industry is a sector of great importance to the country's economy, driving the growth of various other sectors, such as social and technological. In the year 2022, the sector recorded significant growth of 6.90%, highlighting its relevance. However, this growth also leads to the generation of a greater amount of construction and demolition waste, resulting from construction flaws, poor construction management, and the processes of renovation and demolition. In this context, the present research aims to present a sustainable alternative by replacing the fine aggregate from a natural source with fine aggregate obtained from the crushing of structural masonry block rejects, seeking to reduce the consumption of natural aggregate and functionalize waste that could otherwise be deposited in landfills or other spaces that would not facilitate reuse. It also investigates the properties of concrete in both the fresh and hardened states, analyzing the advantages and disadvantages of the methodology employed. Given this scenario, the importance of studies focused on the development of sustainable techniques aiming to optimize mechanisms generated within the construction industry, especially those focused on reuse, the environment, and cost reduction, is understood. In light of the above, this experimental procedure sought to propose, during the concrete mix design, the gradual replacement of only the fine aggregate, keeping all other components constant. The substitutions were determined in increments of ten percent, ranging from zero to one hundred. After the mixture of each concrete matrix with its respective percentage of substitution, tests were conducted in accordance with Brazilian standards, including slump tests, simple compression strength tests at 28 days of curing submerged in a saturated calcium hydroxide solution, and capillary absorption after oven-drying. Regarding the results, it was found that in the range of 10% to 30%, there was a continuous gain in slump, compressive strength, and water absorption compared to the pilot mix (without additions). Between 40% and 70%, there were reductions in both slump and compressive strength, as well as water absorption. However, from 80% to 100%, a different behavior was observed, with a continuous decrease in slump and a significant increase in compressive strength, and results tending to reduce water absorption, but with some variability at 90%. It was also observed that the optimal content with the highest slump and compressive strength results was achieved with 30% substitution. It is worth noting that in all incorporation percentages, there was a gain in strength compared to the pilot mix. Therefore, in line with these data, it is suggested that further studies on the incorporation of concrete block waste into the fine aggregate structure should be conducted to analyze the production and economic viability for the construction market.