Effect of shrinkage reducing admixture on creep of recycled aggregate concrete

It is widely accepted that recycled concrete aggregates originated from construction and demolition wastes are promising materials to contribute to the conservation and rational use of natural resources as well as the protection of the environment. In this work, a comprehensive experimental investigation has been carried out in order to assess the effect of shrinkage reducing admixture (SRA) on the mechanical properties and creep of concrete manufactured with recycled coarse aggregates from the different parent concrete with compressive strengths of 30 MPa and 80 MPa, respectively. Meanwhile, mercury intrusion porosimetry (MIP) and scanning electron microscope (SEM) have been performed to determine the variation of internal microstructure. The results indicate that the quality of recycled aggregates has important effect on the properties of concrete. The addition of SRA furtherly reduces the early mechanical properties of recycled aggregate concrete, and however, improves the later mechanical and creep properties. Compared with the reference concrete manufactured with natural coarse aggregates, concrete manufactured with SRA and recycled coarse aggregates with high quality exhibits the later higher compressive strength and elastic modulus as well as lower creep, which is largely due to the later more compact microstructure such as interfacial transition zone and pore structure.