Variables controlling strength of fibre-reinforced cemented soils

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 (q_t) and compressive strength (q_u) of fibre-reinforced and non-reinforced artificially cemented sand, as well as in the changes of q_t/q_u relationships and particular increases in q_t and q_u 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/C_iv). 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 q_t and q_u. Both q_t and q_u increased linearly with the amount of cement (C) and a power function fitted well as the relation between splitting tensile strength (q_t) and porosity (η) and unconfined compressive strength (q_u) 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 q_t/q_u 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, q_t increased 86% due to fibre insertion and q_u increased just 34·5% due to fibre addition.