Preliminary non-destructive assessment of moisture content, hydration and dielectric properties of Portland cement concrete

Abstract

Moisture availability is a focal point in the structural development of young concrete. Under low humidity and hot weather conditions, concrete loses moisture rapidly as it hardens, and it is very difficult, if not impossible, to minimize this loss even though proper curing procedures are used. Early losses in moisture content jumpstart premature surface self-dissecation, increase surface paste porosity, prevent concrete from achieving the mechanical properties for which it was originally designed, and facilitate the development of surface distresses such as spalling. Curing effectiveness and structural assessment of young concrete is generally done through conventional destructive or invasive testing. However, there is no fully established non-destructive testing protocol to assess moisture content and its effects on concrete properties quantitatively in an on-site, fast, and non-invasive way. The possibility and feasibility of establishing a testing protocol with such attributes is explored. Previous research on pavement bases has used dielectric measurements to relate moisture content to their structural performance. Due to the high dielectric value of water as compared to any other material used in construction, it is possible to relate high volumetric water content to high dielectric readings. In this study, compressive strength tests combined with dielectric and mass measurements are used to investigate how dielectric properties change with hydration. The results of this study suggest that it may be possible to approximate the volumetric moisture content in concrete by measuring the dielectric value of concrete as it hardens.