Concrete shrinkage and creep in recycled aggregate concrete-filled steel tubes

Concrete shrinkage and creep in recycled aggregate concrete-filled steel tubes (RACFST) were experimentally studied and the results were presented in this paper. The measurements on the shrinkage and creep lasted for about eighteen months. The main parameters varied in the tests are: (1) sectional types, circular and square; (2) in-fill concrete types, recycled aggregate concrete (RAC) and normal concrete; and (3) long-term sustained load levels, 0.3 and 0.6. The test results showed that the time-history of the concrete shrinkage and creep in RACFST was similar to that of the corresponding normal CFST. However, the shrinkage and creep strains of RACFST specimens were larger than those of the normal CFST specimens. Finally, the predictive models based on previously issued provision for time-dependent behaviour of the composite member were calibrated with the tests, and recommendations for the calculations on the shrinkage and creep of the concrete core in RACFST were also suggested.