Nanotechnological evaluation of volcanic clays with application in bitumen improvement

Abstract

Clays are raw materials for modern industry and today they are even used for medicines. In an area of 4000 km2 , the San Tadeo geological formation, Ecuador, has a nano clay deposit arranged in six levels (A1 to A6). Physicochemical studies of field samples showed the presence of more than 60% of aluminosilicates in the upper levels A1, A2. Laser granulometry found an average particle size of 30 to 250nm. Nitrogen adsorption-desorption isotherm determined the average specific surface area of 280.3m2 /g. IFTR, XRF, SPECMIN-TSG showed the spectra with the presence of vermiculite, allophane and bentonite minerals. With TGA/DCS a mass loss of up to 42.5% was observed for clays A1, A2, A3, at the final calcination temperature of 1000°C, with endothermic and exothermic manifestations. High adsorption capacity was found for A1 and A2 clays over 30% in their order, and over the other geological horizons; the property was activated when the clay was calcined in the temperature window of 250 to 300°C. EDS, energy dispersive spectroscopy found the presence of Si and Al in the sample of bitumen mixture enhanced with additive A1. SEM confirmed the presence of exfoliated and dispersed A1 additive in the enhanced bitumen mix prepared with 3% by weight of active agent. With DSR (T= 70°C operational) the complex modulus G*= 2326pa (640pa original) and δ = -8.7° points (85° original) were measured, with an improvement of 363%. The new material is applicable as road pavement in medium and high ambient temperature areas due to its higher stiffness