Evaluation of coating mortars with addition of açaí seed (Euterpe oleracea Mart.) in different processing conditions

Abstract

The açaizeiro is a palm tree found in large scale in the northern region of Brazil and one of its main non-timber forest products, with great economic potential. However, the wastes, which represent about 85% of the total fruit, are an environmental problem, since about 365 tonnes of seeds are discarded daily, without any reuse. The objective of this research is to evaluate the potential of reuse of the açaí seed as partial replacement by mass (10%) of the fine aggregate in mortars for coating (1:3 vol ratio). The seeds were crushed and divided into groups to be subjected to different types of treatment, namely calcination and liquid paraffin. Four samples were studied, R1 (reference - without seeds), R2 (calcined seeds), R3 (untreated crushed seeds) and R4 (paraffin treated seeds). The samples were subjected to fresh state tests, hardened state tests and microstructural analyses. The results show that in the fresh state sample R2 shows the best indexes when compared to the reference mix, with only a small improvement in consistency and water retention. In the hardened state, all compositions showed a significant loss of mechanical strength, demonstrating the weakness caused by the waste in the matrix. The microstructural analyses show a slight increase in porosity and amorphism in the sample due to the presence of the waste. For the mixes, substitution ratios, water/cement ratio and treatments adopted, the characteristics of the mortars do not meet the intended use.