A field test for evaluating high performance concrete covercrete quality

Abstract

Since in most deterioration mechanisms fluid ingress plays an important role, the surface skin of concrete provides the initial resistance to such factors as de-icer salt penetration, freeze-thaw resistance, and sulphate attack. Surface durability testing must evaluate resistance to the predominant mechanism of initial fluid ingress: capillary absorption or sorptivity. The primary focus of this study was to develop a test device suitable for nondestructive field use to evaluate the durability of covercrete by determining the rate of absorption of concrete, including high performance concrete. This type of testing device must be simple to use, easily handled in the field, portable, and inexpensive. This particular device allows for ease of operation and accommodates a wide range of surface applications such as vertical, horizontal, or sloped surfaces, and smooth or rough finishes, while providing quick, consistent, and meaningful results. The development of this apparatus was based on principles presented in the British Initial Surface Absorption Test BS 1881, Part 5: 1970, since it focuses on water absorption. Tests of this nature, however, are very sensitive to the in situ moisture content of the surface concrete, as it will drastically alter the rate of absorption. In this paper, the field rate of absorption equipment is described and both calibration and field data are presented.Key words: sorptivity, nondestructive testing, durability, ISAT.