Evaluation of the shear strength of residual limestabilized soils from the Antioquian batholith

Abstract

In general, the construction of roads demands the exploitation of high amounts of granular materials, and this generates important economic and environmental impacts. The use of materials from excavations for the construction of fills and embankments is an ideal solution to reduce the exploitation of virgin materials. However, the use of excavation materials may be limited when these materials are fine-grained or have low mechanical specifications. In this sense, soils stabilized with quicklime have become a viable alternative for road construction, reducing the use of quarry materials. Although there are standards and techniques for the use of soils improved with quicklime for pavements, today the process for evaluating these materials for the construction of embankments and fills is not well established. This research presents the evaluation of the resistance behaviour of residual soils resulting from the weathering of the Antioquian Batolito (Antioquia-Colombia) when are subjected to quicklime stabilization. The optimal percentage of quicklime was determined by means of unconfined compression tests for dosages of 1%, 2% and 3%. Direct shear tests were used to study the influence of quicklime in soil properties like cohesion and friction angle in both natural and stabilized soils. The soil studied corresponds to a silty sand (SM). A factorial 2 x 3 experiment design was made to determine the number of tests with density, quicklime percentage and curing temperature as independent variables and unconfined compressive strength (qu) as response variable. A total of 54 unconfined compression tests and 27-seven direct shear tests were conducted. The results showed a significant increase in the strength of the materials treated with quicklime in relation to the natural state. There were increases greater than 100%, 50% and 15% in cohesion, unconfined compression, and friction angle respectively. The larger increment was calculated with 2% and 3% of quicklime dosage. However, due to cost benefits the optimum percentage of quicklime considered was set to 2%.