Análise da aplicação de cinzas de café arábica na produção de blocos de solo-cal

Abstract

The large number of tailings generated in different human activities and their strict consequences in relation to the environment and the scarcity of natural resources have led to the search for energy efficient materials. In this context, the soil-lime block produced from a homogenized mixture of soil, lime and water presents itself as an alternative, since it does not require burning, avoiding deforestation and air pollution. Studies developed by Milani (2008) and Ferrari et. al. (2014) indicate the possibility of using agricultural residues, such as ash from rice husk and sugar cane bagasse, in the construction of construction elements, thus contributing to reduce the inappropriate disposal of these materials in nature. The present work aimed to study the effects of the incorporation of coffee bark ash (Coffea arabica), on the physical and mechanical properties of soil-lime bricks, in different proportions in two curing periods, in order to rescue the use of raw earth as a sustainable constructive element and provide the residual ash from the coffee husk with an appropriate final destination. The blocks were produced with 7% of lime, inserting percentages of residue, equal to 0%, 5%, 10% and 15% in relation to the dry soil mass. The mixtures were subjected to water absorption, resistance to simple compression, shrinkage and durability by wetting and drying tests. Through the obtained results it was observed that the use of coffee husk ash as a stabilizing agent in soil-lime mixtures is not interesting. In general, the manufactured blocks did not present satisfactory durability and all the compositions containing ash showed lower compressive strength than the control sample. Although some compositions meet the recommendations of the literature for the shrinkage test, most of the mixtures containing ash failed the test because of cracking. The performance of the mixtures evaluated in this study can be attributed to the sensitivity of the soil-lime mixtures, as well as to the chemical composition of the coffee husk ash.