Effect of Porosity/Cement Index on Behavior of a Cemented Soil: The Role of Dosage Change

The adjusted porosity/cement index η/(Civ)a has proved its effectiveness in modeling the strength and stiffness of a variety of artificially cemented soils, being a useful tool for the dosage of soil–cement mixes. In this regard, an analogous mechanical response is expected by establishing a specific η/(Civ)a value, either by increasing the cement content and decreasing the density (or the opposite). Still, the role of this sort of dosage change has not yet been verified for triaxial testing. Particularly, the effect of different dosages assembled at the same η/(Civ)a value has not yet been evaluated considering the effective peak stress parameters. Thus, the present research fulfills this gap by conducting a series of CID triaxial tests in cemented clayey sand. Complementary small strain stiffness tests and unconfined compression strength tests were also carried out. This research comprehended five η/(Civ)a values, considering, at least, three different dosages assembled within each η/(Civ)a. The test data have revealed that both the stiffness and the strength outcomes could be properly correlated to the η/(Civ)a, regardless of the dosage type, resulting in power-type relationships having R2 greater than 98%. Yet, the effective peak stress parameters (ϕ´peak and c´peak) could not be related to the η/(Civ)a index owing to the dosage dependence of the strength mobilization mechanisms. That is, within the same η/(Civ)a, the most cemented and most porous samples presented a cement-dominant response whereas the least cemented and least porous exhibited a density-controlled behavior.