Passive of CRFS Technology in Soil-Cement Application

In Brazil, with the ban on the production, sale, and use of chrysotile asbestos, the sector's industry opted to replace asbestos with CRFS Technology-Cement Reinforced with Synthetic Wire (fiber cement); that is, another product to be disposed of in landfills. This work aimed to determine a composite based on clay, fiber cement powder, and cement that meets the technical specifications of Brazilian soil-cement application standards to contribute to a more sustainable treatment of the future disposal of fiber cement products. With the characterization analysis of the materials, we identified that the clay granulometry is heterogeneous and distributed from 0.1 mu m to 25 mu m. In comparison, 75% of the fiber cement powder has grains greater than 10 mu m. For clay, the liquidity limit is 39.67%, the plasticity limit is 25.01%, and the plasticity index is 14.66%. In the semiquantitative chemical analysis, silicon oxide (SiO2) and calcium oxide (CaO) stood out as the main oxides found, reflected in the mineralogy as quartz and calcium silicate. Therefore, we identified the percentage of organic matter in clay at 2%, using the result of the thermogravimetric analysis. The results described met the normative parameters foreseen for soil-cement applications. That said, the technological characterization was carried out by tests of linear retraction, water absorption, and simple mechanical compression on the specimens made under an axial pressure of 31.2 Mpa in the formulations defined in this work. The formulations with 10% cement and 20% and 30% fiber cement powder are suitable for use in soil-cement bricks, as they have volumetric shrinkage percentages from 2% to 2.5%, water absorption ranging from 18.66% to 19.39%, and simple compressions from 4.25 Mpa to 6.88 Mpa, meeting the requirements of Brazilian standards for soil-cement applications. It is concluded that the results showed that it is possible to produce soil-cement bricks with passive fiber cement products converted into powder, avoiding improper disposal and unwanted environmental impacts.

Automated summary

With the ban on chrysotile asbestos in Brazil, the industry turned to using fiber cement as a substitute, but this created another waste disposal issue. This study aimed to develop a composite material based on clay, fiber cement powder, and cement that meets Brazilian soil-cement application standards. The results showed that it is possible to produce soil-cement bricks from recycled fiber cement products, providing a sustainable solution for their disposal.