Analysis of microcracking formation during basic and drying creep in cementitious materials

Abstract

The safety of double wall Concrete Containment Buildings (CCBs) in the French nuclear fleet primarily depends on the level of prestress applied to concrete. The delayed strains in concrete induced by creep and shrinkage cause a loss of prestress in the inner wall that may increase the risk of potential leaks in accidental conditions. The creep rate in concrete depends on multiple factors among which microcracking is of major significance. In this paper, an experimental approach is being developed for the qualitative and quantitative characterization of creep/damage coupling. The creep behaviour in compression of matured cement paste and mortar is characterised at the macroscale for different hygro-mechanical loadings. A nondestructive Impulse Excitation Technique (IET) is applied for damage evaluation after creep tests by measuring the degradation of the dynamic elastic modulus. The comparison of creep compliances allows creep and shrinkage mechanisms along with microcracking formation to be assessed in the matrix and at matrix-inclusion interfaces. The acquired data will then help to gain insight into the general coupling mechanisms between drying, creep and damage in cement-based materials.