Abstract
In order to find the declay law of mechanical property and the performance difference after salty water and fresh water freeze-thaw cycle, freeze-thaw cycle environments under the salty water and fresh water are simulated. The compressive strength, dynamic elastic modulus and the mass lost are tested. The pore structure parameters are also tested by MIP. Plot the pore diameter distribution curve. The result shows that the compressive strength and dynamic elastic modulus are all decreased. The degree of these two properties decreasing under salty water freeze and thaw recycle is more than the one under fresh water. The parameters of porosity and critical pore diameter become larger. The amount of pores whose diameter is between 100nm and 1000nm increase. The amount of pores whose diameter is under 100nm decrease. The deteriorate degree of pore structure is deeper in salty water than in fresh water.
Highlights
According to the natural zoning of highways, nearly twothirds of the country will be affected by the freeze-thaw cycle
The compressive strength of concrete under salty water freeze-thaw cycle decreases by about 40%, while the reduction range of concrete compressive strength under fresh water freeze-thaw cycle is only 16%
This paper explores the essence of concrete mechanical properties change from the perspective of microcosmic pore structure
Summary
According to the natural zoning of highways, nearly twothirds of the country will be affected by the freeze-thaw cycle. Based on the analysis of pore structure, Zhang Yongcun and Li Qingning studied the frost resistance performance of concrete according to the national standard quick freezing method, that is, the fresh water freezing-thawing method[4]. According to the current research results, the fresh water immersion method mentioned in the national standard is adopted in most of the freeze-thaw cycle tests, which is not conducive to the durability design of cement concrete components. The mechanism of freeze-thaw damage of concrete is still confined to the theory of crystal pressure and osmotic pressure, and the research on the decay of concrete mechanical properties from the perspective of microscopic pore structure is relatively rare. In the research of freeze-thaw cycle simulation of specimens soaked in brine, there are few studies on the decay nature of mechanical properties from the decay mechanism of microscopic pore structures. This study will provide the theoretical support for durability design of concrete in different freeze-thaw environments
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