Key parameter for tensile and compressive strength of fibre-reinforced soil-lime mixtures

The enhancement of local soils with fibres and cementitious materials for the construction of stabilised pavement bases, canal lining and support layer for shallow foundations shows great economic and environmental advantages, avoiding the use of borrow materials from elsewhere, as well as the need for a spoil area. A dosage methodology for fibre-reinforced, Portland cement treated soils has been previously established, based on rational criteria where the porosity/cement ratio plays a fundamental role in the assessment of the target unconfined compressive strength (q(u)). The present research has extended such work by quantifying the influence of the amount of lime, the porosity and the porosity/lime ratio in assessing the tensile (q(t)) and compressive (q(u)) strength of polypropylene-fibre-reinforced silt-lime mixtures, as well as in the evaluation of the q(t)/q(u) relationship. A programme of splitting tensile and unconfined compression tests was carried out in the present study, considering three distinct dry densities and four lime contents, varying from 3% to 9%. The results show that a linear function fits the qt and qu values well with increasing lime content, and a power function fits them well with reducing porosity of the compacted mixture. The porosity/lime ratio is shown to be an appropriate parameter to assess both qt and qu of the fibre-reinforced silt-lime mixtures studied. Finally, the q(t)/q(u) relationship is unique for the fibre-reinforced silt-lime mixtures studied, being independent of the porosity/lime ratio.