Creep characteristics and constitutive model of bio-based concrete in aqueous environment

Bio-based materials generally have high porosity, which are prone to biodegradation during the long-term application, especially in a humid environment. To better understand the impact of the aqueous environment on creep performance of bio-based concrete, the effects of the loading method (single-stage and multi-stage), axial force (50 kN, 100 kN, 150 kN), and water pressure (1 MPa, 2 MPa, 3 MPa) on the long-term creep characteristics of bio-based apricot shell concrete are investigated in this study, with a creep duration of up to 1051 h. The results show that water pressure has a significant effect on the creep properties of apricot shell concrete. The creep strain and creep rate of apricot shell concrete gradually decrease with the increase of water pressure, which attributes to the water confining pressure that restrains the propagation of micro-cracks and consequently reduces the creep strain. Moreover, the creep strain and creep rate of apricot shell concrete increase with the increase of axial force. The creep behavior of bio-based apricot shell concrete in low load level is well described by a proposed Burgers piecewise creep model, which is recommended to express the long-term creep behavior of bio-based apricot shell concrete in the aqueous environment.