Investigation of the dynamic compressive mechanical properties of concrete under the combined effects of freeze–thaw and salt erosion

Abstract

The objective of this study is to investigate the dynamic compressive mechanical properties of concrete under the combined effects of freeze–thaw (F-T) and salt erosion. The Split Hopkinson Pressure Bar (SHPB) test system was employed to conduct dynamic compression tests on concrete specimens subjected to 0 ∼ 250 cycles of F-T in NaCl solutions with concentrations ranging from 0 % to 8 %. The influence of strain rate, F-T cycles, and chloride concentration on the dynamic properties of concrete were analyzed, and a constitutive model considering rate-dependency was developed to describe its compressive mechanical response. The research findings suggest that the dynamic compressive strength of concrete gradually increases with an increase in strain rate, indicating a strengthening effect due to higher strain rates. Additionally, the dynamic growth factor exhibits an exponential relationship with the logarithm of strain rate. Moreover, an increase in the number of F-T cycles results in a gradual reduction in the dynamic compressive strength of concrete and an accompanying increase in specimen fracture. Furthermore, the dynamic compressive strength of concrete exhibits a non-linear trend concerning chloride solution concentration: initially decreasing and subsequently increasing. The minimum compressive strength is observed at a concentration of 3.5 %, indicating the most severe damage to the concrete. However, it should be noted that a higher strain rate mitigates the influence of chloride solution concentration on specimen breakage. To comprehensively understand the mechanical behavior of concrete under combined F-T and salt erosion effects, we propose a dynamic constitutive model based on established mechanical and damage theories relevant to composite materials. The experimental results demonstrate that the proposed model effectively captures the mechanical response of concrete subjected to the combined influence of F-T and salt erosion.