Study on Relationship Between Mechanical Properties and Water Absorption Characteristics of Mortars by Using Digital Image Correlation Method (DICM)

The evaluation of water absorption in concrete is regarded as an important indicator for assessing the causes of its deterioration and durability. Traditionally adopted methods for durability assessment in concrete materials, however, lack in providing real-time monitoring of the absorption process and information about the material deformability at surfaces (volumetric changes) caused by swelling in cement hydrates (i.e., C-S-H). In this study, a one-dimensional water absorption test was performed on small-size mortar specimens of three different strengths, and their top (flattened) surface was continuously monitored for volume changes by utilizing surface strain gauges along with the DICM. After the water absorption test, the same specimens were tested to determine mechanical properties such as compressive strength and Young's modulus. Moreover, the water absorption characteristics, like depth/rate, were evaluated in DICM by tracing changes in waterfront positions with the progression of strains during the water absorption process in mortars. Additionally, the surface strain gauges confirmed the accuracy of strains evaluated by the DICM. The absorption characteristics obtained from observations in the DICM were correlated with the mechanical properties and expansion strain of the test specimens. The results indicated that the durability properties were not only related to the water absorption rate but also to the mechanical properties and volume changes due to saturation.