Micro-cantilever testing on the short-term creep behaviour of cement paste at micro-scale

Abstract

This study proposes an experimental method for studying the short-term creep behaviour of cement paste at micro-scale. The micro-bending tests on miniaturized cantilever beams were used to characterize the viscoelastic properties of cement paste. The effects of w/b ratio, the type of binder and the stress level on the microscopic creep behaviour were investigated. It is found that the short-term creep of cement paste at microscale can be satisfactorily described by a power-law function. A linear viscoelastic behaviour has been observed in different cementitious systems at the microscale with the stress level up to 67.9%. When compared with the creep results in microindentation tests and conventional macroscopic tests, the obtained creep compliance function in this study is found to be both qualitatively and quantitatively representative of the macroscopic results. This experimental study underlines the importance of microstructural effect on the creep behaviours of cementitious materials at microscale.

Modeling of microstructural effects on the creep of hardened cement paste using an experimentally informed lattice model

“…The simulated global creep moduli are found to be quite close to the experimental results. Moreover, according to the experimental investigation in Gan et al (2020), a certain relationship between the global creep modulus and mechanical properties is observed. To examine whether the model can capture this relationship, the simulated mechanical properties, in terms of elastic modulus and strength, are plotted against the global creep modulus in Figure 11.…”

“…The log-power function evolves asymptotically as a power function of load duration for short time and evolves asymptotically as a logarithmic function for long time (Bažant et al, 1997;Di Luzio et al, 2020;Granger & Bažant, 1995;Šmilauer & Bažant, 2010). This is based on the experimental observations that the creep curves of cement paste and concrete exhibit two distinct kinetics depending on the loading duration (Gan et al, 2020;Vandamme & Ulm, 2013;Q. Zhang, Le Roy, Vandamme, & Zuber, 2014).…”

“…The testing results including the static stress-strain curve and specific basic creep compliance evolution for a single sample with the w/c of 0.3 were used here as the benchmark for the identification process. Note that samples with the w/c of 0.3 also have the least scattered experimental results compared to the results of w/c 0.4 and 0.5 samples (Gan et al, 2020). This sample was selected as it has the median basic creep compliance among all the creep tests for w/c 0.3 samples.…”

“…In this study, the virtual specimens containing heterogeneous microstructures were first generated based on the XCT results of cementitious microcantilever beams. The local mechanical and creep properties for different constituents in cement paste were then identified based on the microscale fracture and creep testing results obtained in Gan et al (2020). After the local properties were identified, the fracture and creep simulations were separately carried…”

“…Owing to the recent development of experimental characterization techniques in Gan et al. (2020), we now focus on developing and validating a short‐term creep model at the microscale, which considers the microstructure of cement paste and micromechanical and viscoelastic properties of different constituents. With the validated model, it would be possible to predict the short‐term creep of any cement paste if given the microstructure.…”