Study on the feasibility of using agricultural waste in the production of concrete blocks

Abstract

The construction industry demands a huge extraction of natural resources along with ample energy consumption; hence the search for new technologies is essential to minimize environmental impacts. The incorporation of natural by-products as reinforcement elements in cement matrix composites production has been studied as an alternative to reduce the use of non-renewable raw materials. The most common natural by-products in Brazil are coffee husk and sugarcane bagasse, which, despite their use by some industries, have yet large non-used amounts, needing adequate disposal of and new ways to add value to waste. This work aimed at evaluating the feasibility of producing concrete blocks partially replacing the crushed stones by sugarcane bagasse and coffee husk agricultural waste. For each residue, the replacement percentages of 2.5%, 5%, 7.5% and 10% (V/V) were evaluated (separately), in addition to a formulation without the use of agricultural residues. Agricultural waste was treated for extractive removal and later evaluated based on their morphological, chemical and physical characterization. The mass mix used was 20: 100: 170: 17.05 (cement: sand: crushed stone: water). The blocks were evaluated for their bulk density, water absorption, compressive strength, thermal and microstructure properties. Agricultural waste used as reinforcement improved physical, mechanical and thermal properties of concrete blocks. Sugarcane bagasse showed a greater potential for its use as reinforcement in concrete blocks than coffee husk. The formulation using 5% sugarcane bagasse offered the best results, which allowed the blocks to present the lowest water absorption values and the highest compressive strength values, as well as being one of the best treatments when evaluating thermal properties, meeting all the commercialization standards criteria.