Often, the use of traditional techniques in geotechnical engineering faces obstacles of economical and environmental nature. The addition of cement becomes an attractive technique when the project requires improvement of the local soil. The treatment of soils with cement finds application, for instance, in the construction of pavement base layers, in slope protection of earth dams, and as a support layer for shallow foundations. However, there are no dosage methodologies based on rational criteria as exist in the case of the concrete technology, where the water/cement ratio plays a fundamental role in the assessment of the target strength. This study therefore aims to quantify the influence of the amount of cement, the porosity and the moisture content on the strength of a sandy soil artificially cemented, as well as to evaluate the use of a water/cement ratio and a voids/cement ratio to assess its unconfined compression strength. A number of unconfined compression tests, triaxial compression tests, and m...

Triaxial compression tests were carried out to evaluate the effect of randomly distributed fiber reinforcement and cement inclusion on the response of a sandy soil to load. Cemented specimens were prepared with cement contents of 0% and 1% by weight of dry soil and cured for seven days. Fiber length was of 12.8 mm, in the contents of 0% and 3% by weight of dry soil-cement mixture. Test results indicated that the addition of cement to soil increases stiffness, brittleness, and peak strength. The fiber reinforcement increases both the peak and residual triaxial strength, decreases stiffness, and changes the cemented soil's brittle behavior to a more ductile one. The triaxial peak strength increase due to fiber inclusion is more effective for uncemented soil. However, the increase in residual strength is more efficacious when fiber is added to cemented soil. Peak strength envelopes indicate that the friction angle is increased from 35° to 46° as a result of fiber inclusion. The cohesion intercept is affected...

Unconfined compression tests, splitting tensile tests, and saturated drained triaxial compression tests with local strain measurement were carried out to evaluate the benefit of utilizing randomly distributed polyethylene terephthalate fiber, obtained from recycling waste plastic bottles, alone or combined with rapid hardening Portland cement to improve the engineering behavior of a uniform fine sand. The separate and the joint effects of fiber content (up to 0.9 wt %), fiber length (up to 36 mm), cement content (from 0 to 7 wt %), and initial mean effective stress (20, 60, and 100 kN/m²) on the deformation and strength characteristics of the soil were investigated using design of experiments and multiple regression analysis. The results show that the polyethylene terephthalate fiber reinforcement improved the peak and ultimate strength of both cemented and uncemented soil and somewhat reduced the brittleness of the cemented sand. In addition, the initial stiffness was not significantly changed by the inclusion of fibers.

This work aims at studying the stress-strain-strength behavior of an artificially cemented sandy soil produced through the addition of portland cement. An analysis of the mechanical behavior of the soil is performed from the interpretation of results from unconfined compression tests, drained triaxial compression tests with local strain measurements, and scanning electron microscopy, in which the influence of both the degree of cementation and the initial mean effective stress was investigated. For cemented sandy soils, it was concluded that the unconfined compression resistance is a direct measurement of the degree of cementation. Consequently, the triaxial shear strength can be expressed as a function of only two variables: (1) the internal shear angle of the nonstructured material; and (2) the unconfined compression resistance. In addition, a logarithmic formulation is adopted to express the relationship between static deformation moduli and axial strain amplitude in axisymmetric conditions. Data from other reported investigation programs give to the proposed correlations a broader acceptance to general geotechnical applications.

The enhancement of local soils with cement for the construction of stabilized pavement bases, canal lining, and support layer for shallow foundations shows great economical and environmental advantages, avoiding the use of borrow materials from elsewhere, as well as the need of a spoil area. The present research aims to quantify the influence of the amount of cement, the porosity, and the voids/cement ratio in the assessment of unconfined compressive strength ( qu ) and splitting tensile strength ( qt ) of an artificially cemented sand, as well as in the evaluation of qt / qu relationship. A program of splitting tensile tests and unconfined compression tests considering three distinct voids ratio and seven cement contents, varying from 1 to 12%, was carried out in the present study. The results show that a power function adapts well qt and qu values with increasing cement content and with reducing porosity of the compacted mixture. The voids/cement ratio is demonstrated to be an appropriate parameter to a...