粉煤灰高强轻骨料混凝土抗氯离子渗透及护筋性

Chloride-permeation resistance and the steel protection property of fly ash high-strength lightweight aggregate concrete

利用不同细度粉煤灰等质量取代水泥10%～30%,制备了粉煤灰高强轻骨料混凝土.采用ASTM快速氯离子渗透试验和电化学测试技术,研究了其抗渗性及护筋性能,并与基准试样进行了对比分析.研究结果表明,当粉煤灰掺量相同时,随着粉煤灰细度的增大,轻骨料混凝土抗氯离子渗透性及护筋性均随之增强,且高于基准试样;掺入Ⅱ级粉煤灰时,随着粉煤灰掺量的增加,其抗氯离子渗透性随之降低;掺入超细粉煤灰且掺量为20%时,抗氯离子渗透性最优.而掺入Ⅰ级粉煤灰时,抗氯离子渗透性与基准试样相差不大;而达到30%掺量时,则有下降趋势.同时,钢筋轻骨料混凝土护筋性与抗氯离子渗透性保持大致相同的变化趋势,即随着抗氯离子渗透性的提高,护筋效果随之改善.

Cement has been equivalently replaced by different fineness fly ash, and fly ash high-strength lightweight aggregate concrete have been prepared. The chloride-permeation resistance and the steel protection property of concrete have been tested by the testing method of ASTM rapid chloride permeability and electrochemical technology, compared with that of the reference concrete. The test results show that the chloride-permeation re- sistance and the steel protection property of lightweight aggregate concrete are enhanced and higher than that of the reference sample with the increased of the fineness of fly ash, when the content of fly ash are same. Meanwhile, when grade Ⅱ fly ash is added, the chloride- permeation resistance of concrete reduces with the increase of fly ash content, and the best chloride-permeation resistance of concrete can be reached when ultra-fine fly ash is addedand its content is 20~/4, and the chloride-permeation resistance of concrete has a little change when grade I fly ash is added, compared with the reference sample, but it would decline when the content of grade I fly ash reach 30%. On the other hand, the similar trend of changes, about the chloride-permeation resistance and the steel protection property of con- crete, can be found from tests, and the steel protection effect is improved with the increase of the chloride-permeation resistance.