Geotechnical behaviour and micro-analyses of expansive soil amended with marble dust

The large-scale utilization of waste materials is possible due to their comprehensive geotechnical and mineralogical characterization and their interaction behaviour with soil. No significant attempt has been made to use marble dust, a waste product resulting from the quarrying and crushing of marble, to determine its potential utilization as a geo-material. Thus, an attempt has been made here to clarify the influence of marble dust for improving the geotechnical behaviour of expansive soil and to understand the interactive mechanism. Comprehensive geotechnical tests (Atterberg limits, free swell index, compaction characteristics, swelling percentage and unconfined compressive strength), a physico-chemical examination (pH and electrical conductivity) and micro-analyses (mineralogical, microstructural, elemental, Fourier Transform Infra-Red Spectroscopy and thermal) have been performed using a wide range of marble dust contents up to 80% in order to optimize the marble dust content for soil improvement and to understand its interactive behaviour with soil. The results revealed that marble dust can be utilized effectively to improve soil plasticity and to control the swell behaviour. It is interesting to note that marble dust accelerates the strength of soil at early curing periods and that the optimum improvement in the strength behaviour of the soil is observed with a marble dust content of 20%. Hence, this amount can be considered as the Optimum Marble Dust Content (OMDC). The physico-chemical examination and micro-analyses revealed that alterations in the gradation, cohesion and interlocking among particles, the mineralogical composition, and the microstructural, chemical and elemental compositions are the key factors in controlling the interactive behaviour of soil amended with marble dust. However, the minerals present in the soil and the marble dust, as well as other factors, like the method of curing, the temperature and the longevity, seemed to affect the OMDC; and thus, they need to be investigated thoroughly. (C) 2020 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society.