Investigation of the usability of shales in building brick production and their effects on the final product properties

In this research, the effects of schist additive on the raw material recipe used in the production of a brick factory operating in Afyon province were investigated. It was deemed appropriate to make schist additives at different rates and to use schist with two different grain size distributions in order to detail the research. The raw materials in the raw material recipe used by the company were taken from the company's stock area in accordance with the random sampling method. The schist raw material to be used as additive was also taken from the company's licensed mine site. Since the clay raw materials other than schist are micron-sized, only the lumps due to humidity were dispersed with a hammer and then dried in the oven until they reached a constant weight and sieved below 1 mm. Schist, on the other hand, was crushed with a hammer due to its flaky and occasionally hard structure, dried in the oven until they reached a constant weight, and prepared in two different grain sizes, below 1 mm and below 2 mm. Schists were mixed in the raw material recipe used by the company at 10%, 15% and 20% in both grain sizes. In addition, another recipe was prepared by adding 10% of schist below 2 mm and 10% of schist below 1 mm to the company's recipe. Thus, a total of 8 recipes were prepared together with the reference recipe without additives. Water was added to these mixtures by spraying and kneaded by hand until it reached a plastic consistency, and the material that reached a plastic consistency was left to rest in a closed sample bag for 2 days. As a result of resting, it was shaped in 40-45 gr pieces with a hydraulic hand press, its wet weights and wet dimensions were measured and recorded. The samples, which were kept at room temperature for one day, were then dried in an oven until they reached a constant weight, their dry weights and dry dimensions were measured. The samples were sintered at the determined sintering temperature and their cooked weights and dimensions were measured, they were left in water and their weights in water were recorded with the Archimedes principle. Then, the physical, mechanical and microstructure analyses planned at the beginning of this study were carried out. As a result of these evaluations, it was concluded that the two most ideal recipes are the recipe with 20% schist additives below 2 mm (T4) and the recipe with 20% schist additives below 1 mm (T7). With the increasing schist additive and decreasing grain size; decreases in water absorption and porosity, plasticity water, dry shrinkage and fire loss values, and increases in unit volume weight and compressive strength values were observed. When the firing shrinkage values were examined, it was determined that there were expansions instead of shrinkage. When the SEM analyzes were examined; It was determined that there were smaller and fewer pores in the T4 and T7 samples compared to the R coded sample, and therefore the % water absorption values were lower and the strength values were higher in these samples. In addition, it was seen that there was a more irregular microstructure and pore size in the R coded sample, while a more homogeneous structure was formed in the pores and microstructure in the T4 and T7 samples. As a result of the XRD analyzes; it was determined that quartz, anorthite, illite, muscovite and hematite minerals were formed in the structure of the test samples. As a result, it was concluded that the more we can reduce the grain size of the schist raw material below 2 mm, the more it can be used in certain proportions in recipes as a desired alternative raw material in the brick and tile industry.