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Early freezing of concrete is common in the construction of water conservancy projects in northern China. Early freezing damage induces the deterioration of mechanical properties of concrete structures, which seriously affects the safety, stability and service life of engineering structures. Through laboratory uniaxial compression test and CT scan test, the influence law of freezing time and freezing temperature on the mechanical properties of concrete was analyzed, the three-dimensional pore structure of concrete at different freezing time was reconstructed, the pore distribution and pore structure characteristic parameters of concrete at different freezing time were studied, and the correlation analysis between mechanical properties and pore structure of early frozen concrete was carried out. The results show that with the delay of freezing time, the porosity of concrete test blocks increases first and then decreases, the average pore surface area decreases first and then increases, the average pore diameter increases with the trend of quadratic parabola, and the average pore shape factor increases first and decreases then increases and decreases. The correlation between the average pore surface area and the compressive strength and elastic modulus of early frozen concrete is the best. It is suggested that the average pore surface area should be preferred to construct the mesoscopic damage index of early frozen concrete. Relevant research results provide support for revealing the macro and micro damage mechanism of early frozen concrete.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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