Concrete moisture diffusivity determination using electrical resistivity measurements

The movement of water in concrete structures and buildings is a fundamental subject and therefore it is necessary to understand the mechanisms and processes involved. This paper presents a method to estimate the moisture diffusivity of concrete using gravimetric measurements, together with discretised electrical resistivity measurements. To improve the repeatability of the method, various concrete mixes with and without supplementary cementitious materials were tested. The samples were conditioned under two regimes representing poor and good curing; the samples were then exposed to a simulated hot environment with a diurnal temperature fluctuation of 20-40°C and 60% ambient relative humidity. The basis of the method was to measure the amount of water absorbed by the concrete sample at different depths as a function of time and then Boltzmann's transformation was used to analyse the experimental results obtained. Once a master curve using the Boltzmann transformation is formed, the moisture diffusivity can be obtained. The results showed that the relationship between moisture diffusivity and moisture content can be described by an exponential function.