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Properties of air-entrained concrete subjected to freeze-thaw cycles and salt attack simultaneously
The degradation of concrete subjected simultaneously to frost attack and chemical (salt) attack accelerated significantly. Whether the resistance of concrete to such kind of deterioration could be improved by entraining air bubbles, as the method usually employed against ordinary frost attack, should be demonstrated. In this paper, the properties of concrete with w/c 0.44, 0.32 and 0.26 with (APC) and without (NPC) air entraining exposed to freeze-thaw cycles and NaCl or Na2S04 solution, were monitored. As expected, NPC concrete was deteriorated seriously. For samples with higher w/c in NaCl solution, severe surface scaling occurred. For samples with lower w/c in Na2SO4 solution, the decrease of its relative dynamic modulus of elasticity was accelerated. Obviously, non air-entrained concrete could not resist this kind of attack. When air bubbles with volume content 4.5-5.5 % were introduced, the resistance of concrete improved significantly. Compared to that of NPC, the weight loss of APC samples exposed to freeze-thaw cycles and salt attack decreased more than 50 %, and the ultimate number of freeze-thaw cycles of APC increased evidently. So, entraining air is still an effective method to improve the resistance of concrete against combined attack of freeze-thaw cycles and chemical solution. However, for concrete with higher w/c, entrained air content should not be less than that in this experiment, i.e. 5.5 %.
Properties of air-entrained concrete subjected to freeze-thaw cycles and salt attack simultaneously
The degradation of concrete subjected simultaneously to frost attack and chemical (salt) attack accelerated significantly. Whether the resistance of concrete to such kind of deterioration could be improved by entraining air bubbles, as the method usually employed against ordinary frost attack, should be demonstrated. In this paper, the properties of concrete with w/c 0.44, 0.32 and 0.26 with (APC) and without (NPC) air entraining exposed to freeze-thaw cycles and NaCl or Na2S04 solution, were monitored. As expected, NPC concrete was deteriorated seriously. For samples with higher w/c in NaCl solution, severe surface scaling occurred. For samples with lower w/c in Na2SO4 solution, the decrease of its relative dynamic modulus of elasticity was accelerated. Obviously, non air-entrained concrete could not resist this kind of attack. When air bubbles with volume content 4.5-5.5 % were introduced, the resistance of concrete improved significantly. Compared to that of NPC, the weight loss of APC samples exposed to freeze-thaw cycles and salt attack decreased more than 50 %, and the ultimate number of freeze-thaw cycles of APC increased evidently. So, entraining air is still an effective method to improve the resistance of concrete against combined attack of freeze-thaw cycles and chemical solution. However, for concrete with higher w/c, entrained air content should not be less than that in this experiment, i.e. 5.5 %.
Properties of air-entrained concrete subjected to freeze-thaw cycles and salt attack simultaneously
Eigenschaften von Luftporenbeton nach Frost-Tau-Wechselbeanspruchung und gleichzeitigem Salzangriff
Ru Mu (author) / Miao, Changwen (author) / Breugel, K. van (author) / Sun, Wei (author)
2003
7 Seiten, 3 Bilder, 1 Tabelle, 15 Quellen
Conference paper
English
PROPERTIES OF AIR-ENTRAINED CONCRETE SUBJECTED TO FREEZE-THAW CYCLES AND SALT ATTACK SIMULTANEOUSLY
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