1 Introduction
- The influence mechanism of corrosion was determined by analyzing the microstructure of concrete.
- Experimental research on the corrosion/permeability/frost properties of concrete was carried out.
- The inner influence mechanism of corrosion/permeability/frost was determined by analyzing the microstructure.
2 Materials and Methods
2.1 Materials
2.2 Experimental Design
Type | Strength grade | W/C ratio % | Water kg/m3 | Cement kg/m3 | Fine aggregate kg/m3 | Coarse aggregate kg/m3 | Water reducer kg/m3 | Air entraining agent kg/m3 | Air content % |
---|---|---|---|---|---|---|---|---|---|
A-1 | C50 | 0.32 | 150 | 465 | 764 | 1358 | 6.98 | 0.19 | 5.0 |
A-2 | C40 | 0.38 | 167 | 440 | 568 | 927 | 6.60 | 0.15 | 5.5 |
A-3 | C30 | 0.50 | 155 | 310 | 550 | 760 | 3.72 | 0.09 | 5.5 |
A-4 | C20 | 0.66 | 190 | 288 | 545 | 694 | 1.73 | 0.12 | 5.6 |
2.3 Test Method
3 Durability Analysis of Test Results
3.1 Effect of Different Immersion Methods for Concrete in a Corrosive Environment
3.2 Effect of Different Strengths of Concrete in Corrosive Environments
3.3 Freezing Resistance of Concrete Under Different Water–Binder Ratios
3.4 Anti-permeability of Concrete Under Different Water–Binder Ratios
4 Mechanism Analysis
Characteristic parameters | C20 | C30 | C40 | C50 |
---|---|---|---|---|
Porosity (%) | 24.19 | 20.15 | 14.59 | 11.73 |
Pore volume (ml/g) | 0.1282 | 0.1088 | 0.0900 | 0.0822 |
Pore area (m2/g) | 2.0578 | 7.3231 | 9.5481 | 12.1915 |
Specific surface area (m2/ml) | 16.0514 | 67.3079 | 81.6451 | 148.3150 |
Most probable pore diameter (nm) | 151.0040 | 40.2913 | 44.3119 | 21.0723 |
Critical aperture (nm) | 120.00 | 40.29 | 35.62 | 17.09 |
Average pore size (nm) | 190.9 | 48.6 | 40.8 | 23.0 |
5 Conclusions
- The most rapid corrosion speed was caused by dry and wet cycles, vertical semi-immersion was second, and the slowest was complete immersion among these three immersion types. Corrosion resistance decreases with increasing strength.
- The relative dynamic elastic modulus and freeze–thaw index were very sensitive to the frost resistance of concrete. These two indices are suggested to evaluate the frost resistance.
- The water–binder ratio has an obvious influence on anti-permeability: the smaller the water–binder ratio, the better the compactness of concrete and the stronger the frost resistance of concrete.
- It can be from analysis of the pore structure that the different proportions of pore sizes determine the corrosion, permeability, and frost resistance of concrete. The key to improving the durability of concrete is to change the pore structure of concrete. The smaller the pores and the more uniform their distribution, the better the durability of concrete.
- The smaller the water–binder ratio, the higher the strength and the better the corrosion, permeability, and frost resistance. In a natural environment, it is possible that a variety of factors will act together on concrete, which makes the durability of concrete more complex. Therefore, it is necessary to further carry out experimental research on the durability of concrete under the coupling of various factors.