For the countries with a developed stone industry the waste generated in the natural stone processing plants pose environmental and economic problems. The utilisation of stone waste in various areas is still under research. In addition, there are only a limited number of studies concerning the use of stone waste obtained from processing plants in the stabilisation of clayey soil. Furthermore, none of the studies in the literature investigated the effect of the characteristics of the stone on the stabilisation of the soil. This is the first study that compares the efficiency of the waste calcitic marble, dolomitic marble and granite powder as additives for the stabilisation of clayey soil. Artificial soil samples were prepared in the laboratory using bentonite and kaolinite. Natural stone waste powder was added to the soil samples at different percentages, and the index and compaction parameters of the stabilised soil were analysed. The results showed that the types of waste powder used in this study, like lime, could be used as stabilisers. As the percentage of additives increased, the plasticity index of the clayey soil decreased and the physical properties of the soil changed from clay to silt. In terms of compaction parameters, the use of all types of natural waste powder in the study resulted in a decrease in the optimum water content and an increase in the maximum dry unit weight. The lowest optimum water content and the highest maximum dry unit weight were obtained from the dolomitic marble powder.

Mineral carbonation based on lime (Ca(OH)2) and carbon dioxide (CO2) is a carbon sequestration and also a soil improvement method. This paper investigates the effects of varying Ca(OH)2 (1%, 5%, and 10%) and water ratios (6%, 7%, 8%, 9%, and 10%), and mineral carbonation duration (1 hr, 3 hrs, 5 hrs, and 7 hrs) on the conversion of lime to calcium carbonate in clay-free sand. Two different silicon sand samples which have different grain sizes were used in the experiments. Reacted lime ratio, used lime ratio, and unused Ca2+ ratio were calculated. The lime fixation point was determined as 1% by the total weight of the soil. The average carbonation ratio at the lime fixation point was found to be 84.10 ± 7.75%, which was the highest value. As the lime in the soil increased, the reacted lime and the use of lime decreased. The appropriate water ratio was determined as 6%. Fines supported the conversion of more lime to calcium carbonate. The conversion of lime to calcite was completed in the first few minutes (short-term), but the strength of the lime-treated soil improved over time. The progress of the mineral carbonation reaction in the solid was according to the Dome Principle (DPinC). The conversion of lime to CaCO3 ratio, reacted lime ratio, used lime ratio, and unused Ca2+ ratio was calculated for the first time.

This paper reports for the first time the use and application of a novel technique in the characterization of mineral carbonation reaction and CO2 sequestration in soil stabilization using flow meters. Soils based on SiO2 with two different sizes were tested. Lime (Ca(OH)2) was used as the reactant. Instant CO2 flow rate (L/min), total CO2 volume (L), temperature (°C), and absolute pressure (kPa) were monitored and recorded for 1 hour by flow meters connected to the mold inlet and outlet. It was determined that the mineral carbonation reaction started in the first seconds and ended before the 5th minute. The mineral carbonation is a short-term and potential reaction, and it is not a time-dependent reaction. It is separated from other carbonation reactions with these characteristics. The highest CO2 captured value was obtained in the soil mixed with 5% lime, where fines were not used. The second highest CO2 captured value was obtained in soil mixed with 1% lime, where fines were not used. CO2 captured with 1% lime is more than CO2 captured with 5% lime in the soil containing fines. Accordingly, 1-5% lime can be used in soil carbonation studies. According to the soil properties, the highest CO2 captured and the CO2 efficiency was achieved with the use of 6-7% water by weight.