Z. Chen; M. Dargahi; L. Sorelli
Conference: ConCreep 12 (2024)
Despite decades of extensive studies, the mechanism of concrete creep remains a subject of debate, mainly due to the complex nature of cement microstructure. This complexity is further amplified by the interplay between water and the cement microstructure. The present study aims to better understand the creep mechanism by carrying out creep tests on microprisms of cement paste at hygral equilibrium. First, microprisms with dimensions of 150 µm× 150 µm× 300 µm were prepared by precision cutting from a cement paste specimen with a water-to-cement ratio of 0.4. Subsequently, uniaxial compression and creep tests were carried out on these microprisms within a controlled relative humidity chamber. To mitigate the impact of plasticity and damage, the applied peak load was set at approximately 40% of the compressive strength. Moreover, a coefficient 𝜑𝜑 was developed to account for the foundation effect on microprism creep. Our findings showed that the microscale creep compliance varies by changing the RH level from 90% to 11%. Furthermore, logarithmic and power-law models were applied to simulate creep curves. Lastly, a comparative analysis was conducted to juxtapose these findings with microindentation results from previous works.