The pH measurement of concrete and smoothing mortar using a concrete powder suspension

A simple method is presented to determine the pH value of concrete and fine smoothing mortar. The method is based on mixing powdered samples with a solvent and measuring the pH of the suspension. The parameters affecting the result are investigated. The validity of the pH results is tested by comparing the values measured from a suspension of pulverized specimen with the extracted pore solution. Measurements were done by using a pH electrode and by titration. The technique investigated furnishes results with good reproducibility and has been proven feasible. The pH value results of the proposed suspension method could be compared with the results of the extracted pore solution in two normal-strength concretes and the fine smoothing. Sufficient pore solution of the extra-air-entrained concrete and high-strength concrete could not be obtained in the reference method of extraction of the pore solution. The difference between the results of the suspension method and the extraction method was 0.07 pH units on the average with a standard deviation of 0.27 pH units when the powder-to-suspension ratio in the suspension method was 0.5.