A Study on early Shrinkage of Recycled Concrete

The first 3d early shrinkage of recycled concrete from initial setting time with different replacement rates of recycled aggregate was investigated by self-made equipment. The differences between the unimproved recycled concrete and the improved one are observed, in the latter, new mixing method was utilized，that is, R-aggregates is coated with slag and nanoCaCO3, and relevant mechanism is analyzed. The results illustrate that early shrinkage of recycled concrete outweighs natural concrete, but there is not a definite link between the replacement rate of recycled aggregate and the early shrinkage. The treatment can effectively reduce the shrinkage of recycled concrete in 10h, but can not have a sustaining effort. Prewet treatment will generate water loss channels accelerating evaporation speed of water in concrete to accelerate shrinkage of concrete. The treatment can block water loss channel by coating, and slag and nanoCaCO3 can change pore structure and humidity in concrete to reduce the first10h early shrinkage.