The objective of this paper is to investigate the effect of nano-calcined clay (NCC) and nano-lime (NL) on some engineering properties of the expansive clayey soil. Three soil samples quarried from three different sites in the south of Syria have been investigated. They were thermally treated up to three different levels (450, 650 and 850°C) for 3 hours. Then, they were ground to have a particle size of less than 100 nano-meter. Three replacement levels of NCC were used, i.e. 0%, 1% and 2%. XRD technique has been employed to detect the phases occurring in the clayey samples before and after the thermal treatment. Pozzolanic activity of the calcined clayey soil has been studied using the modified Chapelle test. Atterberg limits, compaction, free swell, swelling pressure, linear shrinkage, shear strength and CBR have particularly been investigated. Test results revealed the positive effect of NCC. Plasticity index (PI) was reduced by more than 50% when 2% NCC was added to the natural soil. In addition, 0.6% NL was added to further investigate the combined effect of NL and NCC on the properties of the clayey soil. All investigated properties were significantly improved when NCC and NL were added together, i.e. swelling pressure and linear shrinkage values were reduced to less than 15% when compared with those of the natural soil.
The objective of this study is to investigate the optimum nano-natural pozzolan (NNP) content in the NNP-based binder concrete. NNP was obtained by grinding a local volcanic scoria for six hours. Twenty-four concrete mixes with four w/b ratios (0.4, 0.5, 0.6 and 0.7) and six-replacement levels of NNP (0%, 1%, 2%, 3%, 4%, and 5%) have been produced. The investigated concrete properties were the compressive strength, the water penetration depth, the concrete porosity and the chloride ion permeability. The efficiency factor (k) of NNP in terms of compressive strength was calculated using the Bolomey equation. Durability indicators have been used to globally evaluate the behavior of NNP-based binder concrete versus control concrete. The results revealed that the efficiency factor (k) decreased to some extent when the NNP content was more than 4%. The calculated durability indicators showed that NNP contents of 3-4% had approximately the highest indicators values. These indicators would be helpful for concrete mix designers. Some correlations between the investigated properties were derived from the analyzed data. The modification of the microstructure of NNP-based cement paste has been observed, as well.
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