Investigation usage of tuffite stone with lime in soil stabilization by standard tests and computed tomography method

Bayburt Stone (BS), a kind of tuffite stone and natural pozzolan, has large reserve around Bayburt City in Turkey. The stone appears green, yellow and white colors because of various physicochemical features. Waste material, up to 70% of total stone, is produced during mining and processing of the stones due to the absence of modern technology . BS has never been used in soil stabilization studies despite its pozzolanic feature. Therefore, usage of BS wastes for soil stabilization is investigated in this study. Test mixtures, for stabilization of high plasticity clayey soil, were prepared with 6% lime (optimum lime ratio) and without lime by adding 0%, 5%, 10%, 15% and 20% of green, white and yellow BS wastes. Index, strength, durability and swelling features of the test mixtures were examined. Besides the experimental studies, micro structure of test mixtures were investigated with scanning electron microscopy and computed tomography analyses. Experimental results revealed that when BS wastes used with lime, it causes better improvement with respect to the soil-lime or the soil-BS mixtures. Maximum strength values, in comparison of white, green, and yellow BS, were obtained from white BS mixtures with lime or without lime. According to unconfined compressive strength test, the optimum results were achieved with ZKB10 mixtures including 10% of white BS wastes and %6 of lime, and according to durability tests, maximum results are attained from ZKY10 mixtures including %10 of green BS wastes and %6 of lime. In the light of the experimental study, white, yellow and green BS wastes have been found to be usable with lime for soil stabilization works and computed tomography has been found to be usable to analyze micro structure of soil.