Assessments of Concrete Internal Damage Caused By Freeze-Thaw Cycles and Mechanical Loading

Abstract

Concrete in bridge decks in Northern States, such as Wisconsin, is subjected to both freeze-thaw cycles and mechanical stresses. Standard testing methods are available to evaluate the deterioration of concrete, including ASTM C215 (Dynamic Modulus test), ASTM C1202 (Rapid Chloride Ion Penetrability test), and ASTM WK37880 (ESR test) are available. In addition, ASTM C642 (water absorption test) helps quantification of permeable voids in concrete. These tests have been used to evaluate undamaged concrete or concrete samples after freeze-thaw cycles. The concrete samples in this study have been subjected to compressive stresses (0.4f_c^') and freeze-thaw cycles (100 to 300 cycles) to better represent the concrete in Wisconsin bridges. It is believed that concrete can develop the microcracks under compressive stresses similar to freeze-thaw cycles. Therefore, the study focuses on the comparison of the standard testing methods on the evaluation of damaged concrete. A total of 36 discs were tested for their chloride permeability in this study. Combined with the other tests conducted for the same samples by Mitchell (2016), it is concluded that: 1) the water absorption after immersion is closely related to the chloride permeability of concrete with internal damage; 2) the average surface resistivity has a strong relationship with chloride permeability of concrete with damage; 3) the average surface resistivity has a closer relationship with water absorption after immersion of cylinders than with average water absorption of discs sliced from the cylinders; and 4) the dynamic modulus seems not efficient in evaluating concrete with internal damage in this study. The permeability of concrete in bridge decks might not be conveniently represented by rapid chloride ion penetration tests; however, the internal damage caused by traffic loading and environmental attacks may be represented well the water absorption of field concrete samples. This line of research is expected to contribute to a durability design methodology that can be used to design bridges for local truck traffic targeting a variety of desired service lives