Relação entre expansão unidimensional e tensão de expansão em solos expansivos tratados com cal e cinza do bagaço da cana-de-açúcar.

Abstract

The expansive soils, characterized by significant volumetric variations in response to changes in moisture content, pose a significant challenge. By absorbing water, these soils expand considerably, potentially causing structural damage due to the uplifting forces resulting from the stresses generated by expansion. To mitigate the issues associated with volumetric variation, one can employ chemical stabilization of expansive soil, which involves the addition of materials rich in calcium and magnesium. This research aimed to investigate the expansive behavior of a soil treated with lime and sugarcane bagasse ash (SCBA), focusing on the relationship between the swelling pressure and the free one-dimensional swell of soil/CBCA/lime blends. To achieve this, tests were conducted using an oedometer apparatus to determine the free swell and swelling pressure of the studied mixtures. The evaluated dosages included 6.5% of CBCA, maintaining an initial moisture content of 19%, while varying the lime content (2%, 3%, and 4%) and the compacted dry unit weight (14, 15, and 16 kN/m³). The adopted methodology relied on the porosity/volumetric lime content ratio (η/Liv) to assess the predictability of free swell and swelling pressure, aiming to establish a correlation between these variables through η/Liv. The results indicated a trend of reduction in both free swell and swelling pressure of the soil. This reduction occurred as the lime content increased and lower values of dry unit weight were observed, also demonstrating a decrease with increased porosity. This trend remained consistent when analyzing the parameter η/Liv and was supported by the analysis of η/(Liv) -0.26, both within the same lime content range and for the dry unit weight. Methylene Blue Adsorption tests were carried out for both the soil without additives and for the soil/CBCA/lime blends. A decrease in the average Cation Exchange Capacity (CEC) values was observed with the increase in lime content, correlating with the reduction in free swell of the soil. The statistical analysis using ANOVA and the Ordinary Least Squares (OLS) method confirmed significant correlations between the variables of swelling pressure and free swell, being statistically significant and directly proportional to each other, concurrently varying with changes in lime content and dry unit weight. Finally, a parametric equation was developed to establish a direct relationship between the parameters of swelling pressure and free swell of soil/CBCA/lime blends.