Estabilização de solos expansivos com cinza do bagaço da cana-de-açúcar.

Abstract

Sugarcane bagasse ash (CBCA) is an industrial residue from sugarcane processing plants, whose improper disposal is harmful to the environment. In this research, CBCA was studied as a sustainable application in the stabilization of expansive soils, to investigate the advantages of this residue in the control of high rates of soil expansion. Expansive soils present volumetric instability when suffering humidity variation and their behavior is characterized by the volume increase (expansion) when there is an increase in humidity and volume reduction (contraction) when they lose moisture, therefore, when used as support capacity in constructions, without being treated and stabilized properly, cause several problems in road works, canals and buildings. The physical, chemical and mineralogical characteristics of the expansive soil (activated calcium bentonite + sand misture), the SCBA and the SCBA/soil mixtures of this research were investigated through the tests of specific gravity of the grains, granulometric analysis, compaction, Atteberg limits, pH, adsorption of methylene blue, X-ray diffraction (XRD), X-ray fluorescence (XRF), single compressive strength and unidirectional expansion. The results revealed that the soil is highly expansive, with expansion potential of up to 20%, plasticity index of 37,80%, presence of the clay mineral montmorillonite, high cation exchange capacity (CEC) and a colloidal activity indicating the presence of a clay active to very active. The CBCA presented a percentage of approximately 23% of magnesium and calcium oxides in its composition. Both materials studied here present alkaline pH and the addition of BCCA contents to the soil caused a 4% increase in soil pH. The addition of contents from 12,50% of SCBA reduced the expansion potential by 99% and the CEC value of the studied soil by approximately 67%. The results of the simple compressive strength tests did not present consistent and satisfactory data for additions below 25%, however, for additions above 25%, the samples tested indicated the possibility of potentially cementing characteristics of CBCA. Finally, it can be seen that CBCA is an industrial waste with great potential for new applications in the stabilization of expansive soils.