Utilization of Earthquake Demolition Wastes and Afşin–Elbistan Fly Ash for Soil Improvement after the Kahramanmaraş Earthquake (6 February 2023)

Abstract

Türkiye is surrounded by active faults that have the potential to produce big earthquakes. Recently, one of these faults has become active. Two earthquakes of magnitude 7.7 and 7.6 occurred 9 h apart on 6 February 2023 in Kahramanmaraş. It is reported that 150 million tons of earthquake demolition waste (EDW) is estimated to be produced as a result of those natural hazards. This waste poses a serious risk to both the environment and human health. Its use in geotechnical applications will provide serious environmental benefits. In this study, Afşin–Elbistan fly ash (AEFA) and EDW were used to stabilize weak clayey soils in different proportions. Samples were prepared by separately adding 5, 10, 15, and 20% AEFA and EDW to high-plasticity clay. The AEFA used in this study was used because the production of AEFA is too high, and it is not used in concrete production because it does not comply with the standards and causes serious environmental problems for the region. The Atterberg limit, standard compaction, unconfined compression strength (UCS), triaxial, and California bearing ratio (CBR) tests were performed on soil samples, and samples were prepared from soil mixtures with various proportions of AEFA and EDW added. In addition, clay mixtures were prepared with EDW by keeping the AEFA ratio constant at 15% and their effects were also investigated. According to Atterberg test results, the natural soil class was determined as high-plasticity clay, the soil class of the mixtures created by adding EDW and AEFA was determined as low-plasticity clay, and all ternary mixtures were determined as low-plasticity silt. In addition, the maximum dry density increased for all mixtures, while the optimum water content decreased. A significant increase was observed in UCS test results, especially in ternary mixtures. While cohesion increased in AEFA mixtures, it decreased in ternary mixtures as the EDW ratio increased. It was observed that the internal friction angle increased in all mixtures. According to CBR test results, it was determined that the binary AEFA mixture ratio was 20%, the binary EDW mixture ratio was 10% and above, and all ratios of the ternary AEFA + EDW mixtures could be used as road sub-base material. After the major earthquake disaster, the use of EDW is of great importance for the environment. As a result, AEFA and EDW were found to enhance the geotechnical properties of clay.