As mechanical characteristics are one of the most important indexes that represent the backfill effect of CPB, curing stress is less considered, thus, establishing a damage constitutive model under the effect of curing stress has great significance for the stability of CPB. Firstly, a multifield coupling curing experiment was developed, and a uniaxial pressure testing experiment was used to test the mechanical parameters. Then, the evolution rule of mechanical characteristics of CPB, considering the effect of curing stress, was analyzed. Secondly, combined with elastic mechanics and damage mechanics theory, a damage constitutive model of CPB was explored. Thirdly, based on the laboratory results, an established damage constitutive model was verified. The results indicate that uniaxial compressive strength (UCS) of the CPB was significantly improved because of increasing curing stress and was also influenced by curing age. It was also shown that there existed four stages for the stress-strain curve of the CPB specimens. Moreover, the stress-strain curves of the model and the experiment’s results were the same. There were also good validity and rationality for the established two-stage damage constitutive model, which can provide a good reference for engineering applications of CPB.

Today, seepage control in tailings dams has become an important problem due to the increased production in mining sites. Although very techniques have been developed to solve this problem, research in this field continues. The reason for this is that there is an ongoing search for a one hundred percent successful method to prevent seepage. In this study, the geochemical and geomechanical properties of paste material stored by the surface paste disposal (SPD) method were investigated by pilot field tests. To determine the effects of cement and pozzolanic materials on the geochemical and geomechanical properties of the paste, 2 different pilot-scale storage designs were observed for about 1 year, with no additives (reference) and binder added to some layers (cement and fly ash). Based on the data derived from the former laboratory investigations and with no additives and with a few layers of cement and fly ash, the two different designs were applied on a pilot scale near the existing tailings dam of a currently active mining enterprise. These designs were observed in inland conditions for about 1 year to determine the effects of seasonal changes on the material. The seepage analysis, surface crack densities, microstructural properties, consolidation, and cohesion values of these designs, which are directly exposed to atmospheric effects, were determined during the study period. According to the results obtained, the use of cement improved the volume compressibility coefficient of the material by approximately 25% compared to the reference design. However, the use of fly ash alongside cement improved the volume compressibility coefficient by about 75%. In conclusion, the use of cement made the material more resistant to external factors, and the usability of fly ash, which was used at a 50% replacement ratio with cement to bring down the cost, for long-time storage in the industry was demonstrated within the scope of the study.

In this study, Afşin Elbistan C-type fly ash (FA) was used, which protects against the sulphate reaction that damages concrete. The detrimental effects of post-reaction decrease with increasing fly ash fineness. The study used 10%, 30%, and 50% weight substitutes of cement. The fly ash was ground in a ball mill for 0, 10, 20, 30, 45, and 60 min, and Blaine fineness values of 1555, 1632, 2347, 2589, 2766, and 3433 cm²/g were obtained, respectively. The effect of the samples on the sulphate resistance was investigated by exposing the samples to 5% or 10% added sulphate solutions, and the compressive strength and ultrasonic pulse velocity of the concrete were tested. The compressive strength values obtained decreased with the increase in sulphate content, and the increase in the grinding time and the amount of substituted FA increased the compressive strength values. It was observed that weight loss increased with increasing sulphate content and decreased with the addition of FA with a high Blaine fineness. It was determined that as the Blaine fineness value increased, the sulphate content, FA substitution amount, and ultrasonic pulse speed decreased. This study was carried out to determine the effects of fly ash used at different fineness and replacement ratios on the performance and strength of concrete after exposure to external influences such as sulphate. The use of fly ash instead of cement will reduce the use of waste materials and natural resources and prevent environmental pollution. The cost of cement and concrete will be reduced.

In this study, by using the texts describing the hazards and precautions taken during text mining, the necessary processes were carried out to first estimate the probability value and severity value of the risk and then calculate the risk values by Natural Language Processing analysis. In order to be used within the scope of the study, two data sets were generated from the data in the risk assessment report prepared by applying the L-type matrix risk assessment in marble quarries between 2015 and 2021. Stochastic Gradient Descent (SGD) was used for classification and prediction by analyzing text data. One data set was used to analyze the probability value of the risk and the other was used to analyze the severity value of the risk. In light of the results, when a text containing hazard and precaution information was entered, a system was developed that analyzed this text, estimated the probability and severity values, and calculated the risk assessment score. The application of the SGD algorithm to learning models developed on text data yielded an accuracy rate of 91.2% in the risk probability data set and 97.5% in the risk severity data set. The results indicated that the models were capable of conducting automatic risk assessment on text data and of effectively predicting the requisite probability and severity values. Due to the high accuracy rates obtained during the study, this risk assessment software was recommended for use in marble quarries.

Too much CO2 is released during cement production. In many researches, the use of natural or recycled compounds plays an important role in the cement composition. The use of these components contributes both to reducing the amount of waste and to protecting the environment in nature. It is possible to produce an environmentally friendly concrete, thanks to its being a fly ash thermal power plant waste and its use as mineral additive in terms of its composition. In this study, it is aimed to produce impermeable concretes with the use of C type fly ash as substitutes for cement in concrete composition in substitution rates of 10 %, 30 % and 50 %. In order to reduce the permeability of concrete in this direction, as a result of grinding the fly ash in the ball mill for 0, 10, 20, 30, 45 and 60 minutes, concrete samples were prepared with and without admixture (Reference). Capillarity test was performed to determine the permeability at the end of cure periods of 28 and 90 days on concrete samples. According to the results obtained at the end of 28 days, the best impermeability was achieved in the mixture with 50 % fly ash replacement and 60 minutes grinding time. In 90 days, the best impermeability was obtained in the mixture with 30 % fly ash replacement and 0 minutes of grinding time. As a result, it was seen that permeability decreased with increasing thinness and substitution rate of fly ash in concrete composition.