In this study, the size effect on the tensile properties of compacted clay was investigated by using deep beam specimens. The equation for calculating tensile strength considering the effect of specimen thickness was established based on the results of finite element analyses. By using deep beams, Brazilian discs, and three-point bending beams, the tensile strength of compacted clay was tested to verify the rationality of deep beam specimens. Furthermore, differences in the tensile properties of deep beams of different sizes (widths of 50, 75, 100, and 125 mm) were explored. The results showed a significant size dependence of the peak load and peak displacement. As the specimen size increased, the tensile strength of the soil exhibited a linearly decreasing trend, whereas the energy required for tensile damage gradually increased. The Ba & zcaron;ant size effect model was used to predict the strengths of compacted clays, and a peak load prediction model that considers the structural parameters of the specimens was developed.

As a result of the development of concrete structures, supplementary cementitious materials have become very important, particularly in structural engineering. Hematite powder, a common iron oxide (Fe2O3) found in rocks and soils, exhibits black, brown, and red colors. After treatment, it enhances the mechanical properties of concrete. This paper aims to highlight the influence of hematite powder on the behavior of high-strength RC deep beams. The experimental program consists of testing twelve deep beams under two symmetrical concentrated loads with different shear span-to-depth ratios of 1, 0.67, and 0.33. The deep beams are divided into three groups according to the shear span-to- depth ratio. Each group has four deep beams that differ in the proportion of hematite powder. Four replacement ratios of hematite powder were used in this study (0%, 1%, 1.5%, and 2%) based on the weight of cement. The experimental results showed that adding hematite powder by 1%, 1.5%, and 2% to the weight of cement increased concrete strength by 5.5%, 18.3%, and 4.16% respectively; splitting tensile strength by 37.8%, 63.4%, and 25.3% respectively; and increased concrete density by 1.86%, 3.4%, and 3.47% respectively. In addition, the experimental test results demonstrated that the ultimate load increases with a decrease in the (a/h) ratio and increases with increased concrete compressive strength. Diagonal crack width and mid-span deflection increase with an increase in the (a/h) ratio and decrease with an increase in concrete compressive strength.