Compressive Stress-Strain Behavior of Seawater Sea-Sand Recycled Aggregate Concrete under Different Strain Rates and Replacement Ratio of Aggregates
摘要
The stress-strain curves of seawater sea-sand recycled aggregate concrete (SSRAC) with different replacement ratios of recycled coarse aggregate (RCA) or sea-sand under different strain rates were studied. The effects of different replacement ratios of RCA or sea-sand, and ages on the characteristic parameters of the stress-strain curve and corresponding dynamic increasing factor (DIF) of SSRAC were analyzed. Scanning electron microscopy (SEM) and nanoindentation tests were used to explain the variation of the characteristic parameters from the microscopic point of view. The results show that, when the replacement ratio of RCA or seasand is 50 %, the strain rate sensitivity of elastic modulus is higher than that of peak stress; the DIF of peak stress exhibits a pattern of initially decreasing and then increasing with the increasing replacement ratio of RCA or sea-sand. Conversely, the DIF of elastic modulus initially shows an increase followed by a decrease. The introduction of seawater and sea-sand promotes hydration, resulting in a denser microstructure for SSRAC as compared to that of recycled aggregate concrete, which influences its strain rate sensitivity. Finally, a stressstrain prediction model of SSRAC is proposed, which can provide a theoretical basis for its experimental research and engineering application.