Porosity-to-Cement Index Controlling the Strength and Microstructure of Sustainable Crushed Material-Cemented Soil Blends

Recently, studies that introduce alternative binders or wastes for created geo-materials that can be mixed with soil to give it greater strength, are of paramount importance. Roof tile residue, for example, has been widely used to create geopolymers in mortar and concrete. However, its application to soil stabilization has been limited. Additionally, there are no recent studies on the design of soil-tile mixtures with criteria, based on the estimation indexes of mechanical resistance, durability, and microstructure. Thus, this paper introduces another new geo-material not studied in the current literature: crushed roof tile (RT) waste mixed with soil-cement. For this, sedimentary soil was mixed with cement (C) and RT in various quantities and cured under 28 days. The influence and impact of the porosity/cement index (η/Civ) on the split tensile (qt) and compressive (qu) strengths were studied. Concerning porosity, as well as the cement content, it had a strong influence on strength. Regardless of the cement content used, a decrease in the material’s porosity promoted considerable gains in strength due to a more significant number of contacts between particles and a more outstanding interlocking between the soil particles. In addition, the greater ability to distribute stresses within the geomaterial compacted specimen and the greater capacity to mobilize friction in lower porosity states to contribute to the strength of the RT-soil-cement mixture. The index split tensile/compression was calculated as 0.18, independent of cement and the RT content. During the chemical microanalysis, the soil particles and the RT detected the cementing material between the soil particles. Finally, the new geomaterial can be applied to several uses in geotechnical engineering. From an environmental point of view, the RT-soil blends are considered technically sustainable. Reconciling sustainability and the development of new materials is, without a doubt, essential for us to progress in society. Cemented soil with RT residues have emerged recently and are a potential replacement for traditional materials, as demonstrated in this paper.

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