A closer look at the temperature effect on basic creep of cement pastes by microindentation: Fid-Bau Portal

A closer look at the temperature effect on basic creep of cement pastes by microindentation

Frech-Baronet, J. / Sorelli, L. / Chen, Z.

Highlights • The microindentation creep of cement pastes is logarithmic in time at temperatures ranging from 10 to 60 °C. • The asymptotic logarithmic creep rate of a cement paste is not significantly affected by temperature. • Existing creep results under uniaxial compression test can be modeled by a thermo-activated characteristic time. • Temperature accelerates the basic creep mechanisms without affecting the asymptotic logarithmic creep rate.

Abstract While several works have investigated the effect of temperature on concrete creep, the effect of thermal activation on the multiple creep mechanisms is not fully understood. This work aims at investigating the thermal effect on the creep rate of cement pastes with different water-to-binder ratios ( $w / b$ ) by microindentation technique. Firstly, several results of compression creep tests, which are available in open literature, were compared showing that the uniaxial creep modulus $C_{u}$ is lower at greater temperature within a temperature range of 20–80 $°$ C. Then, several microindentation creep tests were carried out on cement pastes with different $w / b$ ratios (from 0.2 to 0.6) at a constant temperature ranging from 20 $°$ C to 60 $°$ C and at a constant relative humidity of 30%. All the microindentation creep curves exhibited a logarithmic creep compliance $J = (1 / C_{i}) \log (t / τ + 1)$ with a clear influence of the $w / b$ ratio. Surprisingly, the effect of the temperature on the indentation contact creep modulus $C_{i}$ was rather negligible, with the only minor exception of the cement paste with high $w / b$ =0.6. Finally, creep tests were reanalyzed by assuming an Arrhenius equation for the characteristic time $τ_{arr}$ rather than for the creep modulus $C_{u}$ . Eventually, the presented microindentation creep results along with the reanalysis of existing macroscopic data suggest that temperature accelerates the kinetics of basic creep without affecting the the long-term logarithmic creep rate of basic creep.