Characterization of Pore Structure and Crack Propagation in Concrete Using X-Ray Computed Tomography

Abstract

This thesis utilized the method of computed tomography to quantify the pore structure and the development of cracks in concrete specimens due to delayed ettringite formation. The pore structure is responsible for the passage of harmful substances through the concrete matrix, while delayed ettringite formation causes expansion and internal cracking in concrete structures; particularly in prestressed and precast concrete elements. Computed tomography is a relatively new technique that can be utilized to determine the pore structure and crack propagation in concrete specimens within the mm to micrometer range. The experiment was successful in quantifying the pore structure in the specimens. The pore sizes and total porosity of each specimen were determined along with the pore size distribution on diameter and volume. A comparison was then made with the mercury intrusion porosimetry technique. However, the second objective of analyzing internal cracking due to delayed ettringite formation was not met.