Efeitos da adição de resíduo de cinza de caldeira em misturas de solo e cimento na absorção de água e na resistência à compressão simples

Abstract

Due to the industrial growth and the generation of waste and biomass, measures have been taken so that the waste has as its final disposition the reuse, reuse in different materials or recycling. Biomass boiler ash is a waste whose final destination is compost or landfill. Research related to the use of waste has addressed the potential of using ash from various production processes, aiming at its incorporation into soil-cement bricks. The soil-cement technique can be used to make bricks, blocks, monolithic walls, paving, among others. In the mixture, most of it is the soil, and its properties can be modified in order to obtain the desired product. In this work, the dosage of the soil-cement and residue mixture will be done by establishing adequate proportions of soil-cement and ash residue in triplicate specimen moldings for each molding point, to verify the influence of the cement content, weight apparent dry specificity and voids/cement ratio from simple compressive strength test. The soil is composed mostly of fines and clay and the ash residue has a higher fraction of sand in its composition. In general, it was found that in soil-cement samples for a specific weight of 17 kN/m³ there were no gains in the values of resistance to simple compression, as the cement content increased, differently from what was observed for the specific weights of 16 kN/m³ and 16.50 kN/m³. The addition of ash and cement residue generated a linear growth in the values of resistance to simple compression, for the three dry specific weights. As for the influence of the dry apparent specific weight, it is noted that in soil-cement samples the specific weight was significant for lower cement contents and in soil-cement-ash residue samples the variation in specific weight did not generate resistance gains to simple compression. It was found that the addition of ash residue and cement content, improved the performance of the mixture, providing less dispersion in the points of the empty/cement ratio curve and generated gains in the values of resistance to simple compression. The incorporation of ash residue in the soil-cement mixture provided the specimens with less capacity to absorb water. Based on the analysis of the statistical results, the best dosages were established for calculating the costs of the raw material for making soil-cement-ash bricks, the most economical being the brick composed of soil, 30% gray, 11% cement with specific weight of 16 kN/m³.