On creep characteristics of cement paste, mortar and recycled aggregate concrete

This paper first presents an experimental study on shrinkage and creep behaviour of cement paste with different water to cement (w/c) ratios. It is found that the shrinkage and creep behaviour of cement paste increase with the increase of w/c ratios. The effects of external environment (such as temperature and relative humidity) on the shrinkage behaviour are clear but not on the creep behaviour. Besides the experimental study, a creep model of cement paste and mortar is established based on the relationship between w/c ratios and a compliance function of cement paste. It has proved that the predicted results are accurate. Finally, based on the above achievements, the creep mechanisms of recycled aggregate concrete (RAC) are simulated on a modelled RAC by a finite element method analysis. The simulation results reveal that the stress distributions of mortar and coarse aggregate change overtime during the whole creep process. The result indicates that the effects on creep characteristics by old mortar on the modelled RAC are significant