Compared with the natural aggregate

the recycled aggregate has the outstanding characteristics of smaller density

larger water absorption and crushing index.A comprehensive mix design theory of recycled coarse aggregate concrete

concerning the effects of the mix proportion design method

the water/cement ratio

the properties of the recycled coarse aggregate and the recycled coarse aggregate replacement rate

has not been formed systematically.Based on a regression analysis of the compression strength database of 104 groups of recycled coarse aggregate concrete（RAC）

which is designed on the basis of the normal concrete mix proportion design method

this paper developes an empirical strength model for recycled coarse aggregate concrete.The effects of the water to binder ratio

the recycled coarse aggregate crushing ratio and the recycled coarse aggregate replacement ratio on the strength of RAC are revealed in the model.A comparative analysis shows that the predictions made using the strength model are very accurate and the mean error is within 6.5%.This indicates that the empirical model can be used for the strength design of RAC.