Comportamento tensão – deformação e resistência ao cisalhamento de uma areia de duna cimentada artificialmente

Abstract

In recent decades a number of studies have been conducted in order to understand the behavior of soil with cementation (natural or artificial) between particles. The sands studied here generally exhibit good bearing capacity. However, it is often necessary to improve the soil to increase static support capacity or even to consider the effect of natural cementing that occurs in some sands. To that end, it is important to understand the mechanical behavior of cemented soils. The general aim of this study was to describe stress-strain-strength behavior of artificially-cemented sand from the Dunes of Natal, Brazil by means of unconfined compression and drained triaxial compression tests. The influence of cement content, molding moisture, void ratio and confining stress on strength was assessed and the validity of using the void/cement factor in estimating unconfined compressive strength, shear strength in drained conditions and stress-strain behavior was determined. Unconfined compression test samples were molded using different molding moisture levels (6%, 9% and 12%), different cement content (2.5%; 5.0%; 7.5% and 10%) and a void ratio of 0.6. In triaxial compression tests, all the samples were molded in 6% moisture with three void ratios (0.6; 0.7 and 0.8) and four cement contents (0.0%; 2.5%; 5.0% and 7.5%), and rupture occurred under different confining stresses (50, 100, 200 and 300 kPa). The cementing agent used was high-early-strength Portland cement, with sulphate resistance (CP-V ARI – RS). It was concluded that unconfined compressive strength rises with an increase in cement content and a decline in molding moisture. It was found that shear strength increases with a rise in the amount of cement and a decrease in void ratio. It was also observed that the variation in friction angle values was practically negligible when compared to the change in cohesion intercept. Finally, it was found that the void/cement factor was a very effective and reliable parameter for predicting the behavior of Natal Sand in order to determine the soil-cement dosage.