硝酸银显色法测量混凝土中非稳态氯离子迁移系数的误差分析(英文)

为了评估硝酸银显色法测量非稳态氯离子迁移系数（Dnssm）的误差,采用NTBuild 492中的显色法测量了30组含不同矿物掺合料类型、2个水胶比的砂浆试件。试验结果和理论分析表明：如果不控制硝酸银显溶液的喷洒体积,变色边界氯离子浓度（cd）为0.030～1.020mol/L,当变色深度为5mm时,cd将产生40%Dnssm误差,这对评价高性能混凝土是相当不利的;喷洒的硝酸银溶液体积越小,cd的变化越小。基于本文建立的硝酸银喷洒程序[其中硝酸银溶液喷洒体积为（0.30±0.06）L/m2],假如采用cd=0.070mol/L计算Dnssm,当变色深度（Xd）为5mm时,将产生20%Dnssm误差。在cd=0.200mol/L的情况下,即使Xd小于5 mm,Dnssm误差仍然小于5%。因此,cd=0.070 mol/L并不适合用来计算Dnssm。建立的硝酸银喷洒程序及cd=0.200 mol/L用来测量并计算Dnssm是合理的。

Error Analysis for Measurement of Non-Steady State Chloride Migration Coefficient in Concrete Using AgNO_3 Colorimetric Method

To evaluate the error of non-steady-state migration coefficient(Dnssm) caused by AgNO3 colorimetric method,colorimetric measurement for 30 mixtures of mortar specimens with different types of binder and water-binder ratios(0.45 and 0.35) were con-ducted according to the NordTest Build492.The experimental results and theoretical analysis indicate that if the volume of sprayed AgNO3 solution is not controlled,the chloride concentration at the color change boundary(cd) can range from 0.03% to 1.020 mol/L.This could produce 40% error of Dnssm when the color change depth(Xd) was 5 mm,which could be unfavorable for the high per-formance concrete.The less volume of sprayed AgNO3 solution,the less change of cd could be.Based on the established AgNO3 spraying procedure(in which the volume of sprayed AgNO3 solution was(0.30±0.06) L/m2),if 0.070 mol/L of AgNO3 solution was used for the calculation of Dnssm,it could produce 20% error of Dnssm when Xd was 5 mm.In the case of cd of 0.200 mol/L used for the calculation of Dnssm,the error of <5% was obtained even when Xd<5 mm.Therefore,cd of 0.070 mol/L was not proper to be used for the calculation of Dnssm.The established AgNO3 spraying procedure and cd of 0.200 mol/L could be reasonable for the determination of Dnssm.