Durability Performance Study On The Nitric Acid Erosion Of Sprayed Concrete

With car emissions increasing, nitrogen oxide nitric acid. Tunnel lining concrete structures, especially single permanent shotcrete lining structure durability have an impact. Nitric acid erosion sprayed concrete test had beening carried out to research the vehicle exhaust effect on the properties of sprayed concrete structure durability.The sprayed concrete in long-term immersion test had beening carried out to analyze the change of the erosion of sprayed concrete durability performance nitrate solution from microscopic, mesoscopic and macroscopic three aspects.Method for different erosion time and different p H value, mineral composition and microstructure of sprayed concrete were analyzed by means of X-ray diffraction(XRD), and scanning electron microscopy(SEM). Explaining nitric acid erosion process from the microscopic view. It is concluded that the erosion mechanism of shotcrete and nitrate microstructure change rule.Sprayed concrete alkalinity of pore solution and nitrate quality percentage was studied, alkalinity and nitrate quality percentage with soaking time and p H value of sprayed concrete was investigated. Observe the sprayed concrete basicity change law and mechanism of migration of nitrate after erosion.The impact of soak time, p H value, and steel fiber on sprayed concrete quality loss rate, compressive strength, splitting tensile strength, thickness of injury, and relative dynamic elastic modulus were reserched. Sprayed concrete appearance morphology changes were described and analyzed. The calculation model of relative dynamic elastic modulus and compressive strength, splitting tensile strength, damage layer thickness was established. The influence coefficient of steel fiber, researching the variation of steel fiber and sprayed concrete after erosion compressive strength, splitting tensile strength, damage layer thickness were introduced.Nitrate eroded ordinary concrete and shotcrete specimens basic performance variation were analyzed. The influence of the difference between failure mechanism in the process of nitric acid erosion of its durability were researched.