Temperature and RH of normal concrete and mortar subjected to drying in an indoor residential environment

Abstract

The evolution of internal temperature and relative humidity distributions in initially saturated normal concrete and mortar cubes of 0.4, 0.5 and 0.6 w/c ratios stored in an indoor residential environment were recorded for over a year. Measurements at regular intervals were taken at six different depths from the exposed drying surface in each specimen. Results reveal that, the internal temperature at all depths in mortar and concrete samples followed the transitions of ambient temperature closely irrespective of the w/c ratio. While the effect of w/c ratio on the mean internal relative humidity in mortar was statistically negligible, it became discernible in concrete at points where the medium had relatively lower saturation levels and when the effect of evaporation was low due to a low ambient temperature. Higher dosages of Polycarboxylic ether based superplasticizer was observed to delay the drop of internal relative humidity. The recorded values of internal relative humidity over the period of study were found to be conducive for the onset and propagation of carbonation induced corrosion. A two parameter linear model for the prediction of critical drying time with respect to spatial distance from drying surface is also proposed.