Creep behavior for concrete incorporating coal gangue coarse and fine aggregates

Employing coal gangue as aggregate can greatly affect the long-term behavior of concrete, yet there has been limited research focused on the creep characteristics of concrete made with coal gangue aggregates. To address this gap, an experimental study was carried out to examine the creep characteristics of coal gangue aggregate concrete (CGAC) that utilizes both coal gangue coarse and fine aggregates (CGCA and CGFA). Furthermore, a creep model for CGAC was introduced to consider the impact of these aggregates. Experiments were carried out to quantify the creep deformation of CGAC with varying replacement ratios of CGCA and CGFA and two water-cement ratios (w/c) of CGAC. The findings revealed that: (1) both CGCA and CGFA significantly increased creep deformation of concrete, resulting in a 35.8 %–134.9 % higher final creep deformation of CGAC compared to NAC; (2) the CGCA had a stronger impact on creep deformation than CGFA; (3) the influence of CGCA and CGFA on the final creep deformation decreased as the decrease of w/c; (4) the incorporation of CGCA and CGFA had a minimal effect on the creep development of concrete. Based on the experimental results, a creep model for CGAC was proposed. This model includes an amplification factor that considers how the reduced stiffness of aggregates in CGAC, when compared to NAC, impacted the final creep deformation. Finally, the verification results indicated that the proposed model can well predict the CGAC creep, with a maximum deviation in the final value of 7.6 %.