Experimental and Numerical Assessment of Restrained Shrinkage Cracking of Concrete Using Elliptical Ring Specimens

Effects of specimen size on assessment of shrinkage cracking of concrete via elliptical rings: Thin vs. thick

“…In fact, due to geometrical effect, the radial deformation of the central restraining elliptical steel ring is not uniform along its circumference when concrete shrinks [15,16]. Therefore, it is believed that the uniform internal pressure assumption is not appropriate for elliptical ring specimens.…”

“…The mechanism of the elliptical ring test has been largely unexplored since only Zhou et al [15] and Dong et al [16] have conducted research trying to figure out under which conditions the elliptical ring cracks earlier than circular ones. However, those studies only focused on thin rings.…”

“…Besides, in contrast with the fact that a crack may initiate anywhere in a circular ring specimen, for an elliptical ring specimen of a given geometry, it tends to be at a determinable position, reducing the resources needed for detecting crack initiation/propagation in the ring test. Therefore, elliptical ring specimens have been employed for assessing cracking tendency of cement-based materials as an improved ring test by some researchers [11][12][13][14][15][16]. However, most of those studies focused on investigating the effects of variations in material proportions/additives on the restrained shrinkage cracking of concrete or other cement-based materials.…”

Assessment of behaviour and cracking susceptibility of cementitious systems under restrained conditions through ring tests: A critical review

“…It is worth pointing out, however, that the selection of elastic modulus and calculation of degree of restraint will not be necessarily representative of concrete's behaviour because creep effects are disregarded. Although a reference value of elastic modulus is used in the majority of the conducted studies, few authors adopted a decrease in the elastic modulus of concrete by 40% in calculations or simulations, in order to account for the effects of creep [33][34][35]82,[89][90][91][92][93][94][95][96]. It is also worth to remark that concrete E-modulus endures significant changes during the actual experiment (as well as creep behaviour), which even adds more complexity to this analysis.…”

“…which is the static elastic modulus reduced to 60% [33][34][35]82,[89][90][91][92][93][94][95][96]. In this comparison, both original and "effective" elastic moduli are considered in both equations in order to explore the differences between the calculated values of degrees of restraint.…”