碱硅酸反应交流阻抗谱研究及其合理应用

以快速砂浆棒法为比较,用交流阻抗谱方法对几种集料的潜在碱活性和由此引起的碱硅酸反应对砂浆密实性、抗渗性和氯离子扩散性的影响进行了研究.结果表明:有潜在碱活性的集料与普通集料有不同的交流阻抗响应,可以根据其特征阻抗谱在复平面中的相对位置以及相角的大小来评定集料的碱活性,所得结果与快速砂浆棒法检测的结果有较好的相关性.交流阻抗谱方法有可能发展为评定集料碱活性的方法.在适度的碱硅酸反应存在的情况下,砂浆密实性、抗渗性提高,氯离子扩散阻抗系数变大.利用这一特性可以提高混凝土的耐久性和使用寿命,这对于具有一定潜在碱活性集料的合理使用有参考价值.

Study of AC Impedance Spectroscopy for Alkali-Silica Reaction and Its Rational Application

The potential alkali reactivity of aggregates and the influence of alkali-silica reaction(ASR) on compactibility,impermeability and behavior of diffusivity of chloride of mortars were investigated by AC impedance spectroscopy.It is shown that the AC impedance response is different when the potential alkali reactivity exists in the aggregate,and a good parallel correlation exists as compared to the results of accelerated mortar bar test.The position of impedance plot in complex plane and phase angle can be used to estimate the potential alkali reactivity.Impedance spectroscopy is of promise to be developed as a measure to evaluate the potential alkali reactivity of aggregate.In addition,if the ASR is controlled to a certain extent so that the deterioration induced by expansion of concrete structure does not appear,the durability and service life of concrete could be improved.The compactibility is shown by impedance technique to increase significantly and the impermeability,the diffusivity of chloride decreases to a great extent in the presence of ASR.These effects are expected to be of great promise in the future use of some alkali reactive aggregates.