Study On Concrete Performance Under Load And Sulfate Attack

Concrete is widely used in construction of tunnels,bridges and houses due to its meature construction technology and it's economical,practical,and durable.Concrete structures under load are vulnerable to severe erosion in the environment of sulfate,so it is of great significance to improve the durability of concrete structures to study the effects of load and sulfate erosion on concrete performance by experiments.Test pieces of ordinary concrete and imitation steel fiber concrete were prepared in the test,and the performance was studied after 28 days of standard curing.By the experiments of concrete under load,the compressive strength and dynamic modulus of elasticity of the two types of concrete under different loading ratios are studied.By the experiments of sodium sulfate attack on concrete under different conditions,the surface characteristics,quality,thickness of corrosion layer and compressive strength of two kinds of concrete under the effect of sulfate attack were studied.The damage of the concrete in 150-d wet and dry cycle was analyzed by a spectrum detector.By the experiments of concrete with load and sodium sulfate,the change law of sulfate ion concentration,compactness and compressive strength in two concretes was studied.The test results show: the compressive strength and dynamic elastic modulus of ordinary concrete and steel-fiber-reinforced concrete increase under 15% and 30% axial compressive load ratios.Dry and wet cycling can accelerate the corrosion rate of sodium sulfate,compared with long-term soaking,the performance of concrete changes significantly under the wet and dry cycle.Under the combined action of sodium sulfate and dry-wet cycle erosion for 150 days,the quality and strength of ordinary concrete first increased and then decreased,and the thickness of the corrosion layer first decreased and then increased,this phenomenon becomes more obvious as the sodium sulfate concentration is higher.The spectral curve of concrete shows strong absorption characteristics at the wavelengths of 1440 nm and 1940 nm,the change of reflectance reflects the changes of concrete hydration products and erosion products,and the spectral curve of concrete changes most in 10% sodium sulfate solution.Under the combined action of load and sulfate attack,the sulfate ion concentration in both types of concrete increased,and the compactness increased first and then decreased,and the compressive strength was positively correlated with the change in compactness.The imitation of steel fiber in concrete can increase the strength of concrete and effectively resist sodium sulfate attack.Figure 45;Table 34;Reference 60...