Evaluation of concrete creep properties based on indentation test and multiscale homogenization method

Abstract This paper aims to quantitatively evaluate the creep properties of concrete through microscopic tests with a multiscale mechanical homogenization method considering interface transition zone (ITZ). The concrete samples with 0 or 10% silica fume were subjected to a 360-day macroscopic test. A series of indentation tests, microscopic tests and theoretical studies were carried out to obtain the creep properties of individual phases of hardened paste and contact creep modulus and thickness of the ITZ around coarse aggregate. Results indicated that the addition of silica fume significantly improved the quantity and quality of gel in the matrix. Meanwhile the performance of ITZ was enhanced while its thickness was decreased by 29%. The above effects contribute to the improved ability of concrete to resist creep. To quantitatively evaluate the creep properties, the concrete materials were divided into four different scales from nanoscale to macroscale. A homogenization method combining Mori-Tanaka (MT) scheme and self-consistent (SC) scheme was used to calculate the contact creep modulus of concrete. Besides, two ITZ simulation models of bond-slip and homogeneous solid were discussed on the fourth scale to verify the accuracy of the model and confirm the significances of ITZ properties and thickness in creep analysis.