Porosity/Cement Index Controlling Flexural Tensile Strength of Artificially Cemented Soils in Brazil

When the soil does not attain a target mechanical behaviour, modifying the project, removing and replacing the material or improving the soil is necessary. Adding Portland cement to soils and performing densification through compaction are effective approaches for ground improvement. Tensile strength is a mechanical property employed to evaluate the performance of cemented materials, and it can be assessed by flexural tensile strength tests and splitting tensile strength tests. The porosity/cement index has been shown to govern the splitting tensile strength of artificially cemented sands, but no attempt was made to find a relation between this ratio and flexural tensile strength. Hence, this study aims to quantify the influence of porosity, Portland cement content and the porosity/cement index on the flexural strength of three artificially cemented soils (sand, silt and silty sand). An experimental program of flexural and splitting tensile strength tests, as well as unconfined compression tests, was carried out to assess that influence on specimens with different porosities and cement contents. Results demonstrate that the porosity/cement index is an appropriate parameter to assess the flexural strength of the artificially cemented silty and sandy soils. The ratio between flexural tensile strength and splitting tensile strength was found to be 3.31, 4.59 and 5.19 for artificially cemented sand, silt and silty sand, respectively, being independent of porosity, cement content and porosity/cement index.