超高性能混凝土渗透性的三种电测方法比较

Comparison of Three Electrical Testing Methods for Evaluation of Permeability of Ultra-high Performance Concrete

利用ASTM C1202法、NT Build 492/RCM法及NEL法对三种市售超高性能混凝土(UHPC)基体预混料的渗透性进行了检测,以分析其适用性。结果表明:ASTM C1202电量法的测试结果均在100 C以下,难以进行更加细致的区分;NT Build 492/RCM电迁移法即使在60 V下通电500 h,试件中的氯离子显色深度也多在2 mm以内,由显色深度读数引起的测试误差较大;NEL饱盐电导率法的测试结果与现有研究结果基本吻合,考虑测试结果的区分度,该法仍是UHPC渗透性检测的首选之法,但其可靠性仍需更多的实践检验;对于无需测试氯离子扩散系数的场合,可直接采用规定测试条件下的试件电导率(或电阻率)来比较材料的渗透性高低。

The ASTM C1202,NT Build 492/RCM and NEL test methods were used to compare the permeability of three commercial ultra-high performance concrete(UHPC)matrix premixes,and the applicability of these methods was analyzed.The results show that the ASTM C1202 electric charge method is mostly below 100 C,and it is difficult to make a more detailed distinction.For the NT Build 492/RCM electric migration test method,the chloride penetration depths after 500 h at 60 V are mostly within 2 mm together with large reading errors causing unavoidable fluctuations.The results of the NEL salt saturated conductivity method are basically consistent with the data reported in the literature,and considering the principle and the resolution,the NEL method is currently the preferred method for UHPC permeability evaluation even though its reliability still needs further practical inspections.For those cases the chloride diffusivities unnecessary,the electrical conductivity or resistivity of the UHPC can be directly employed to compare its permeability under the same testing conditions.