Effects of Recycled Concrete Powder on Early-Age Properties and Chemical Shrinkage of Alkali-Activated Binder
TIAN Jiaqing
QIN Yongjun
ZHU Shengchao
LUO Ling
Abstract：To investigate the influence of recycled concrete powder(RCP)replacing fly ash on the properties of alkali-activated binder(AAB),three replacement rates of RCP,namely 10%,20%,and 30%were set up.A systematic analysis was conducted on the changing patterns of the setting time,fluidity,compressive strength,and chemical shrinkage of AAB.Moreover,microscopic testing techniques such as scanning electron microscopy-energy dispersive spectroscopy(SEM-EDS),X-ray diffraction(XRD),and mercury intrusion porosimetry(MIP)were employed to characterize the composition of hydration products,microscopic morphology,and the evolution characteristics of pore structure.The results show that when the replacement rate of RCP is 30%,the setting time and fluidity of AAB decrease by 38.6%and 17.1%,respectively,compared with those without RCP,while the 7 d compressive strength and 3 d chemical shrinkage increase by 16.7%and 326%respectively.Microscopic analysis reveals that RCP can significantly increase the calcium-silicon ratio of AAB,promote the generation of hydrated calcium silicoaluminate(C-A-S-H)gel,and optimize the pore structure through secondary hydration reactions and physical filling effects,thereby significantly enhancing the compactness of AAB.
Keywords：alkali activationrecycled concrete powder(RCP)workabilitymechanical propertychemical shrinkage
Publication Date：2026-02-28
Online Publishing Date：2026-04-07(First online date of this platform, not the publication date of the document)
Pages：8( 185-192 )