Water-Induced Swelling Displacements in Core Drilling Method

This paper discusses the nondestructive technique of core drilling to evaluate stresses in concrete. Core drilling measures the displacements found near a hole drilled in concrete and relates this to stresses present in the structure by using elasticity theory. During core drilling, the introduction of water causes concrete to swell. These swelling displacements directly lead to errors in estimating the stresses. In this paper, the author provides a way to correct these water-induced swelling displacement errors. Using the values presented in the research literature as a basis, the author estimates the depth of water penetration and the swelling strain due to water exposure. The apparent stresses are estimated using finite element modeling. Results, which are applied to an earlier non-related hole-drilling investigation, show that proper accounting for water-induced swelling displacements significantly improves accuracy in prediction.