高频振动对引气混凝土引气参数和抗冻能力的影响

针对两种引气混凝土施加不同时间的高频振动,采用硬化混凝土气孔结构分析仪定量地描述振动对引气混凝土含气量、气泡间距和气泡孔径分布等参数的影响,通过冻融循环试验反映高频振动与引气混凝土抗冻能力的关系。结果表明:振动施加初期混凝土含气量变化不大,随振动时间的延长(约60 s后),含气量开始大幅下降,约105s后,含气量下降放缓,最终趋于稳定;随高频振动时间的延长,混凝土气泡间距系数先增大再减小,气泡平均直径不断减小,比表面积不断增大;480～960μm的气泡对高频振动更为敏感,0～480μm的气泡在混凝土中较为稳定;长时间的高频振动会直接劣化引气性能,造成混凝土抗冻融能力下降。

Effect of High Frequency Vibration on Air-Entraining Parameters and Freezing Resistance of the Air Entrained Concrete

High frequency vibration of different time was applied on two kinds of air-entrained concrete.Pore structure analyzer of hardened concrete was applied to quantitatively describe the influence of vibration on air content of the air-entraining concrete,the spacing factor and the pore size.Meanwhile,the freeze-thaw cycle test could accurately reflect the relationship between high frequency vibration and the freezing resistance.The results showed that the air content changed little when vibration was imposed at the beginning.Then,it began to decrease obviously(about 60 s later).After about 105 s,the air content decreased slowly and finally tended to be stable.The coefficients of the spacing factor of concrete increased initially and then decreased.Meanwhile,average diameter of bubble decreased and the specific surface area increased.The air bubble whose diameter was between 480 μm and 960 μm was more sensitive to high frequency vibration.On the contrary,the air bubble whose the diameter between 480 μm and 960 μm was stable.In addition,long time of high frequency vibration would directively degrade the air-entrained ability and the freezing resistance would decline.