Practical evaluation of rapid tests for assessing the Chloride resistance of concretes containing Silica Fume

The present study is an exploratory research that appraises and compares the performance of four rapid tests for assessing the chloride penetration of concrete; Rapid Chloride Permeability Test (RCPT), Rapid Chloride Migration Test (RCMT), Surface Electrical Resistivity (SR) and Modified Rapid Chloride Permeability Test (MRCPT). Due to the concern raised by some researchers on that the conductivity of the pore solution impinges upon the results on some of these rapid tests, silica fume was used as supplementary cementitious material in proportions of 7.5% and 15%. All four methods exhibited substantial reduction in the chloride permeability of concrete mixtures containing silica fume compared to the control mixture at the ages of 28 and 90 days. The variations in performance caused by silica fume usage were significant for RCPT and SR methods, moderate for RCMT and marginal for MRCPT. Results show that the variation in the conductivity of the pore solution significantly alters the results of SR and RCPT tests, and marginally alters those of MRCPT.