PDF
Full
Outline
To study the evolution law of member properties of hydraulic concrete materials under the coupling effect of freeze thaw cycles and salt erosion, early frozen specimens with different air-entraining agent admixtures (0, 0.005%, 0.01%) were selected and placed in a composite solution with a mass fraction of 3.5% sodium chloride +5% sodium sulfate for freeze-thaw cycle tests. Based on nuclear magnetic resonance (NMR)-fractal theory, the coupling relationship between the fractal dimension of the concrete pore volume and the damage degree of the specimens was constructed. The results show that the addition of air-entraining agents in concrete materials in appropriate amounts can effectively improve the mechanical properties such as elastic modulus and compressive strength of the members under the effect of salt freezing, and can improve the pore structure and frost resistance. The fractal dimension of concrete pore volume tested by nuclear magnetic resonance gradually decreases with the increase of freeze-thaw cycles, which indicates that the addition of air-entraining agent can change the internal pore structure of concrete in the initial state, and the effect is more obvious with the increase of air-entraining agent mixture. The correlation model between fractal dimension of pore volume and compressive strength was established by combining fractal theory, and the best functional relationship between fractal dimension DMAX and compressive strength was found to be approximately exponential function. The regression coefficients R2 is greater than 0.85, and the fitting effect is ideal, which provides a reference for durability assessment of concrete structures.
PDF
132
42
| 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 |
关闭全屏
No. 86 Xueyuan South Road, Haidian District, Beijing
010-62199257
qkjq@cast.org.cn
Copyright © 2025 China Association for Science and Technology. All rights reserved. For all open access content, the relevant licensing terms apply.
Sponsored by the Office of the Leading Group for Cybersecurity and Informatization of CAST, and supported by Science and Technology Review Publishing House
