Papers by Keyword: Chemical Erosion

Abstract: As a countermeasure against deterioration of reinforced concrete structures that have suffered from salt damage, materials containing salt adsorbents have been developed. In this study, the basic properties of the “Hybrid Epoxy Resin Repair Agent” in which a functional adsorbent was added to an epoxy resin were grasped and verified. As a result, chloride ion adsorption effect assuming repair of salt damage and sulfate ion adsorption effect assuming chemical erosion repair was confirmed.

Abstract: The complicated geological condition of the deep roadway is the important factors to influence the stability of the surrounding rock and the safety of mining. The rock specimen is taken from a coal mining of Jiangxi province. The chemical solution with different ion concentrations and PH value were prepared to simulate the complex environment of the deep roadway, and the specimens were immersed in the solution then carried out the axial compression test. The strength and other mechanical parameters of the specimen were obtained and the experimental results showed that the strength of the specimen being immersed all are lower than natural state. The reduced values become large with the immersed time and acid value increasing.

Abstract: In order to effectively assess the concrete strength and deformation property under sea water erosion environment, concrete stress and strain curve was researched with the number of wet and dry cycle of 0 times, 10 times , 20 times, 30 times, 40 times, 50 times and 60 times based on the large-scale static and dynamic stiffness servo test set. The stress - strain curves of concrete was tested for the lateral pressure 10.8MPa, 14.4MPa, and 18.8MPa at different dry-wet cycles, The failure modes and superficial cracking characteristics of specimens are reported at different dry-wet cycles. Concrete elastic modulus and compressive strength were researched. Based on concrete mechanical theory , the classic Kufer-Gerstle strength criteria of concrete was used, a large number of test samples of multivariate data were nonlinear regressed, a biaxial concrete strength criterion was established taking into account the stress ratio and the number of dry-wet cycles.

Abstract: In order to effectively assess the concrete damage under sea water erosion environment, concrete prediction damage model was presented based on damage mechanical and the experimental test. The degeneration of tension strength of concrete was tested after dry-wet cycles. The fact is proposed that the degeneration of concrete is an interior damage evolving process. Freezing and thawing damage accumulation of concrete was analyzed based on the discrete grid with probability of stochastic method. Three-dimensional multi- parameters Weibull distribution model about concrete damage evolutions were presented. Parameters were estimated based on gradient method. The mathematical model was verified using measured data. Corresponding algorithm was designed to establish concrete durability prediction model under sea water chemical erosion conditions. The research can be referenced for prediction of frost damage of concrete.

Abstract: The Magnesium phosphate cement was prepared from MgO and NH₄H₂PO₄. The changes of the strength, appearance and hydration products of the magnesium phosphate cement were investigated, which are soaked in sulfuric acid solution, sodium hydroxide solution, sodium sulfate solution and magnesium sulfate solution. Besides, the impermeability and salt frost resistance of magnesium phosphate cement were analyzed. The results show that magnesium phosphate cement has good resistance to sulfate erosion, especially the anti-corrosion ability of magnesium sulfate. However the alkali resistance of the magnesium phosphate cement is poor. Therefore, the magnesium phosphate cements are not appropriate to be used in alkaline environment as cementitious material. The resistance of the magnesium phosphate cement to chemical attack is closely related to the stability of the hydration product MgNH₄PO₄• 6H₂O. The magnesium phosphate cements have good impermeability and salt freezing resistance.