Variables controlling strength of fibre-reinforced cemented soils

Abstract

This study aimed to quantify the influence of the amount of cement, the porosity and the porosity/cement ratio in the assessment on tensile strength (qt) and compressive strength (qu) of fibre-reinforced and non-reinforced artificially cemented sand, as well as in the changes of qt/qu relationships and particular increases in qt and qu due to fibre insertion. The controlling parameters evaluated were the fibre content (F), the cement content (C), the porosity (η) and the porosity/cement ratio (η/Civ). A number of splitting tensile and unconfined compression tests were carried out in fibre-reinforced and non-reinforced artificially cemented sand specimens. The results showed that fibre insertion in the cemented soil, for the whole range of cement studied, caused an increase in both qt and qu. Both qt and qu increased linearly with the amount of cement (C) and a power function fitted well as the relation between splitting tensile strength (qt) and porosity (η) and unconfined compressive strength (qu) and porosity (η) for both the fibre-reinforced and non-reinforced specimens. It was also shown that the porosity/cement ratio, in which volumetric cementitious material content is adjusted by an exponent (0·28 for all the fibre-reinforced and non-reinforced cemented soil mixtures of this study) to end in unique correlations for each mixture, is a good parameter in the evaluation of the splitting tensile strength and unconfined compressive strength of the fibre-reinforced and non-reinforced cemented soil studied. Finally, the unique qt/qu relationships equal to 0·14 (fibre-reinforced sand cement specimens) and 0·10 (non-reinforced sand–cement specimens) were found, being independent of the porosity/cement ratio, qt increased 86% due to fibre insertion and qu increased just 34·5% due to fibre addition.