Evaluation of Adding Grits in the Manufacture of Soil-Cement Bricks

Abstract

The production of residues in pulp and paper industry is continuously increasing, which generates storing expenses and greater environmental impacts. The grits is an inorganic solid waste generated during the Kraft process by the pulp and paper industry, which presents in its composition the main ingredients of Portland cement. Therefore this paper aims to evaluate the feasibility of incorporating grids to the manufacture of soil-cement compressed bricks. To set the ideal amount of waste to be used, various samples with varying contents of cement, soil and grits were carried. The materials were characterized by mechanicals, physical and environmental tests and the results are consistent with the prescriptive requirements. Regarding the compressive strength at 28 days, all samples had their mean values higher than the normalization, which is 2.0 MPa. The bricks produced with higher amount of grits showed better performance in compressive strength.

The global manufacture of pulp, paper and paperboard have been increasing at constant rates since 1960. In 2012 a production of 204 million tons of pulp and 507 million tons of paper and paperboard were registered. Brazil, for instance, produced 14 million tons of pulp and 10 million tons of paper and paperboard generating 240 thousand tons of grits in 2012. Hence, Brazil is positioned as the fourth worldwide producer of pulp and the eleventh producer of paper and paperboard [1]. Grits are yellowish solid and granulated residues from calcined green liquor, composed of sintered and vitrified lime.

In this context, the pulp and paper industries are faced with the challenge of increasing the production and, simultaneously, solving the problems related to the final disposal of residues. In the search for a solution to the final destination of these residues, innumerous researches are being developed in order to minimize the economic and environmental impacts of its final disposal. An interesting alternative is the utilization of these residues as a construction material to produce new technologies to the civil construction [2, 3, 4, and 5]. The incorporation of grits residue to the manufacture of soil-cement compressed bricks is a feasible solution from the technical and economic perspectives. This is due to the facts that grits have similar granulometry of a soil considered adequate to the production of soil-cement bricks and it presents two of the most abundant components in cement (lime and silica) in great quantity.

Therefore, the aim of this paper is to evaluate the feasibility of incorporating grits residue to the manufacture of soil-cement compressed bricks, obtaining the maximum consumption of residue and respecting the regulatory requirements.