SR48 A literature survey of electrical techniques for measuring concrete moisture profiles (2007)

Failure of polyvinyl chloride sheet flooring and other impervious materials on concrete base slabs, due to entrapped moisture, is a recurring problem. However, no clear guidelines exist to aid designers in deciding how long a concrete slab will take to dry out.

A literature survey was carried out to determine which of two electrical techniques for measuring moisture profiles in concrete slabs was the most feasible and worthwhile developing for research purposes.

The first part of the survey deals with the nature of concrete and hydrating cement paste insofar as it concerns the way water is held and located and is able to move within the matrix. Following a survey of the way in which the moisture condition may be characterised by the dielectric properties, techniques of profile recovery using dielectric (microwave) and resistivity techniques are discussed.

It is recommended that the resistivity technique be pursued, as much of the technology exists and need only be modified. Dielectric techniques are less extensively reported in the literature. The ability of a microwave technique to resolve sufficiently deep profiles remains uncertain. Nevertheless, effort in developing microwave techniques should proceed so as to capitalise on the complementarity of the two approaches.