Usability of Kayseri volcanic slags as filling material on flexible paved roads

Kayseri Volcanic slag (VC) is a natural material containing soil-sized rock fragments, pozzolanic minerals and volcanic ash formed as a result of explosive volcanic activity. Volcanic slag exists as ready aggregate in nature in the form of conical slag hills or as waste from building foundation excavations. The purpose of this study is to demonstrate the usability of the volcanic slag aggregates, which are naturally abundant in Kayseri, and after stabilization with cement in the construction of road or airport pavements and to encourage the diversification of filling materials in regions where resources are limited. The results have shown that VC is suitable for road fill and subbase layer, but it does not have sufficient strength to be used in road base layers and cannot be used in fill of base layer of highways without soil improvement. In order to investigate the use of VC in the base layer of highways, strength tests were conducted by stabilizing it with 3% and 5% cement. As the best result, with 5% cement mixture by weight, 7 and 28 days UCS strength of 3.1 MPa and 4.97 MPa were obtained, respectively, and CBR strength was obtained at 108.4% and 148.6%, respectively. These values meet the strength requirement specified in the standards for the base layer of the highways. As a result, it has been demonstrated that the geotechnical properties of volcanic slags can be improved by stabilizing them with cement, and can be used as a construction material in base fill, subbase and base layers of flexible paved roads and in all kinds of fillings.