低温(3℃)养护条件下不同水灰比混凝土细观孔结构及抗氯离子渗透性试验研究

Research on theeffect low temperature(3 ℃) curing condition and various water-cement ratio have on theresistance to chloride ions penetration and mesoscopic structure of concrete

为研究低温(3℃)养护条件和水灰比对混凝土抗氯离子渗透性和细观孔结构的影响规律及程度,采用气孔分析法和直流电量法对低温(3℃)养护条件下和标准养护条件下的不同水灰比混凝土28 d细观孔结构和电通量进行测试。试验结果表明:低温(3℃)养护条件对不同水灰比混凝土孔径分布有显著影响,使其孔径粗化严重,大孔含量增多,小孔含量减少;气孔间距系数和平均孔径都明显大于对应标准养护条件下的混凝土,且都随着水灰比增大而增大,低温(3℃)对低水灰比混凝土平均孔径影响程度大,对高水灰比混凝土平均孔径影响程度小;不同水灰比混凝土28d电通量值也明显大于其标准养护条件下的混凝土,且随着水灰比增大,电通量值逐渐增大,抗氯离子渗透性逐渐减弱;低温对不同水灰比混凝土孔结构和抗氯离子渗透性都产生不利影响,使混凝土细观孔结构劣化,抗氯离子渗透性降低,且对低水灰比混凝土的影响程度大。

In order to study the influence rule and degree of the chloride penetration resistance and mesoscopic structure of concrete,stomatal analysis method and DC power law are adopted in this research.These two meth-ods are used to measure the mesostructure and DC value of the concrete with different water-cement ratio cured 28 days under low temperature （3 ℃）and standard curing condition.The result shows that：the effect on con-crete pore size distribution is obvious with low temperature （3 ℃）curing condition on the different water-ce-ment ratio of concrete.When the aperture is seriously coarsened,the coarse pore increases apparently,and the number of mesoscopic pore decreased.Pore spacing factor and average pore diameter were significantly greater than the corresponding concrete standard curing conditions,and it goes larger with a higher water-cement ratio. But under the condition of low temperature （3 ℃）,it behaves a relatively higher effect on the average pore di-ameter of concrete with a lower water-cement ratio and lower effect on it with a relatively higher water-cement ratio.The DC value is higher on concrete with different water-cement ratio cured 28d than it is cured under standard curing conditions.Besides,the DC value goes higher as the increase of water-cement ratio,and the chloride penetration resistance decreases at the same time.Low temperature has negative effect both on concrete pore structure with different water-cement ratio and the chloride penetration resistance.It leads to the degrada-tion of concrete mesoscopic structure and the decrease of permeability.The effect of low temperature on concrete with lower water-cement ratio is also higher.