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.

Shear strength is the key index to determine the stability of a soil slope, and cementation between iron oxide and clay minerals is one of the internal factors affecting soil shear strength; however, the effects of the form of iron oxide on the shear strength of granite-weathered red soil are still unclear. Kaolinite, which is the main clay mineral of granite red soil, was selected as the research object, and the effects of three different forms of iron oxide (hematite: HT, goethite: GT, and amorphous iron oxide: AIO) on the soil microstructure, microscopic quantitative parameters, cohesion, internal friction angle, and shear strength were analyzed by scanning electron microscopy, X-ray diffraction, and the shear strength test. The results revealed that the iron oxide promoted the cementation of soil particles, and the cementation characteristics differed with the different forms of iron oxide. Hematite mainly showed flocculent cementation, poor cementation, and simple soil microstructures. Goethite mainly exhibited acicular cementation and the best cementation effect. The degree of aggregation of the soil particles was increased by the coatings, thus forming larger aggregate particles. The cementation effect of amorphous iron oxide was between those of hematite and goethite but included both the flocculation cementation of hematite and acicular cementation of goethite. Amorphous iron oxide and goethite effectively increased the contact area and friction degree between soil particles, while hematite had the opposite effect. The addition of three kinds of ferric oxide reduced the fractal dimension of soil, increased the apparent porosity, and promoted the irregularity of particles to a certain extent, among which hematite had the most significant growth on the long and short axes of the particles. At a content of 10 g kg-1, the addition of AIO and GT increased the soil cohesion and internal friction angle, and therefore increased the soil shear strength, and it was mainly determined by the soil microstructure: the contact area, apparent porosity, and particle short axis. These results indicated that GT and AIO are the main cementing materials affecting soil mechanical properties, and the transformation of iron oxide should be paid attention to when predicting soil slope stability.

The extraction and processing of iron ore produce significant amounts of mine tailings, causing environmental problems that require storage in reservoirs or dams. Using these materials in construction helps minimize their adverse impacts. This study analyzed the geotechnical properties of Magnetite and Hematite iron ore tailings (MIOT, HIOT) from the Golgohar mine in Sirjan, Iran. Two IOTs were compacted using the Standard Proctor technique after being treated with 5, 7, and 9 % Portland cement. Following curing time, treated samples were tested at different stress levels for resilient modulus. Based on the results, to meet strength and durability requirements, cement-treated MIOT needs 9 % cement. Contrastingly, only 5 % of the cement for cement-treated HIOT met the criterion. The resilient moduli of untreated MIOT and HIOT materials heavily rely on the confining pressure, resulting in a minimal decrease in modulus by increasing deviatoric stress. The effect of cement on resilient modulus is more pronounced in high confining stresses than in low confining stresses in MIOT and HIOT materials. A comparison of different non-linear models showed that 'Universal' model is the best fit for laboratory results of cement-treated MIOT and HIOT materials, as it accounts for hardening and softening behavior.

The morphology, mixing state and hematite content of polluted mineral dust are not well accounted in the optical models and this leads to uncertainty in the radiative forcing estimation. In the present study, based on the morphological and mineralogical characterisation of polluted dust, the three-sphere, two-sphere and two-spheroid model shapes are considered. The optical properties of the above model shapes are computed using Discrete Dipole Approximation code. The single scattering albedo, omega(0), was found to vary depending on hematite content (0-6%) and model shape. For the two-sphere BC-mineral dust system, hematite was found to be a dominating absorber compared to that of black carbon as the R-BC/R-dust decreases. The omega(0) of the polluted dust system is larger if polluted dust is considered as pure dust spheroid (with 4% hematite) while smaller value is observed for Q(ext). Among all the systems, the omega(0) of BCBCD (two BC spheres attached to one dust sphere) system showed the maximum departure (40 and 35% for polluted dust with 0 and 6% hematite, respectively) from that of pure dust spheroid with 0 and 6% hematite. For the Asian region (pollution-prone zone), the modelled polluted dust optics will help to trace the optical and radiative properties of dust.