TY - JOUR
T1 - Hydration kinetics and modified model for effective water to cement ratio control in recycled aggregate concrete
AU - Duan, Zhenhua
AU - Li, Julun
AU - Zou, Shuai
AU - Huang, Tianyong
AU - Li, Bo
AU - Hu, Zhangli
AU - Li, Long
N1 - Publisher Copyright:
© 2025 The Authors
PY - 2025/12
Y1 - 2025/12
N2 - The rapid urbanization surge has intensified the dual challenges of natural aggregate depletion and construction waste accumulation, necessitating sustainable solutions like recycled aggregate concrete (RAC). However, the higher water absorption of recycled aggregate (RA) disrupts the effective water-to-cement (w/c) ratio, critically impacting RAC performance. While prior research focused on RA water absorption ratio or empirical w/c ratio correlations of RAC, the interplay between RA moisture dynamics and hydration kinetics remained unexplored. This study bridges this gap by systematically investigating how RA initial moisture degree (Dim) and additional water ratio (Raw) influence hydration behavior through isothermal calorimetry. A modified Krstulovic-Dabic hydration kinetics model, incorporating Dim and Raw dependent correction coefficients (pi, qi), was developed to elucidate hydration mechanisms. Key findings reveal that RA with Dim ≤ 0.5 reduced cumulative hydration heat by up to 11.8 % due to water absorption, while Dim ≥ 0.75 enhanced heat release by up to 14.3 % via internal curing. The duration of the interactions at phase boundaries process gradually shortened and even disappeared with the increase of Raw under low Dim (≤ 0.5). A critical Dim threshold of 0.65 balanced water transport equilibrium, aligning effective and nominal w/c ratios. By linking RA moisture states to hydration kinetics, this study provides a framework for optimizing RAC mix designs with controllable effective w/c ratio, advancing sustainable construction practices.
AB - The rapid urbanization surge has intensified the dual challenges of natural aggregate depletion and construction waste accumulation, necessitating sustainable solutions like recycled aggregate concrete (RAC). However, the higher water absorption of recycled aggregate (RA) disrupts the effective water-to-cement (w/c) ratio, critically impacting RAC performance. While prior research focused on RA water absorption ratio or empirical w/c ratio correlations of RAC, the interplay between RA moisture dynamics and hydration kinetics remained unexplored. This study bridges this gap by systematically investigating how RA initial moisture degree (Dim) and additional water ratio (Raw) influence hydration behavior through isothermal calorimetry. A modified Krstulovic-Dabic hydration kinetics model, incorporating Dim and Raw dependent correction coefficients (pi, qi), was developed to elucidate hydration mechanisms. Key findings reveal that RA with Dim ≤ 0.5 reduced cumulative hydration heat by up to 11.8 % due to water absorption, while Dim ≥ 0.75 enhanced heat release by up to 14.3 % via internal curing. The duration of the interactions at phase boundaries process gradually shortened and even disappeared with the increase of Raw under low Dim (≤ 0.5). A critical Dim threshold of 0.65 balanced water transport equilibrium, aligning effective and nominal w/c ratios. By linking RA moisture states to hydration kinetics, this study provides a framework for optimizing RAC mix designs with controllable effective w/c ratio, advancing sustainable construction practices.
KW - Effective water to cement ratio
KW - Hydration kinetics
KW - Hydration model
KW - Moisture degree control
KW - Recycled aggregate concrete
KW - Resource sustainability
UR - https://www.scopus.com/pages/publications/105014918306
U2 - 10.1016/j.cscm.2025.e05217
DO - 10.1016/j.cscm.2025.e05217
M3 - Article
AN - SCOPUS:105014918306
SN - 2214-5095
VL - 23
JO - Case Studies in Construction Materials
JF - Case Studies in Construction Materials
M1 - e05217
ER -