Longitudinal restraining devices for the evaluation of structural behaviour of cement‐based materials: The past, present and prospective trends

Abstract

The problem of thermal and shrinkage cracking in concrete has been long recognised by researchers and engineers as it can jeopardise the intended serviceability of a concrete structure. This has led researchers to develop testing devices which aim to simulate the behaviour of concrete under restrained deformations. Such devices are discerned in passive and active, depending on how concrete's movement is restrained, whilst a new type of devices has been developed to account for the combined effects of intrinsic restrained deformations and externally imposed actions. This paper presents a detailed and critical literature review on the developed restraining devices and an analysis of the capabilities, complexities and peculiarities associated with their use. Further to this, the challenges the developers of testing devices are faced with, the gaps and uncertainties with the methods found in the literature and recommendations for potential improvements in the field are discussed. K E Y W O R D Screep and shrinkage, heat of hydration, restraining devices, restraint, shrinkage cracking, thermal cracking, viscoelasticity

Control of Early-Age Cracking in Super-Long Mass Concrete Structures

“…It was found that the method is sensitive enough to resolve different levels of shrinkage and its evolution in time, and that the effect of the operator is not significant. Many types of equipment have been developed for the assessment of restrained thermal, drying, and/or autogenous shrinkage, but there are several uncertainties and limitations with their use [24]. The thermal and shrinkage deformations of concrete are usually restrained by boundaries in practical engineering.…”

Comparison of thermal cracking potential evaluation criteria for mass concrete structures

“…The restraint ring test [9,10], the slab test [11,12], the uniaxial restraint test (e.g., the rigid cracking frame (RCF) [13][14][15] and the temperature stress testing machine (TSTM) [16][17][18][19][20]) are some common methods in the lab for evaluation of restraint cracking sensitivity of concrete, and other recently developed restraining devices (e.g., drying shrinkage restraining rig, variable restraint testing machine) also have played a positive role on restraint cracking potential evaluation, which can be found in the literature written by Kanavaris et al [21]. It is known that the classical restraint ring and the slab test cannot reflect the temperature effect on the cracking potential of earlyage concrete due to the lacking of temperature controlling parts.…”