Early-age shrinkage assessment of cementitious materials: A critical review

With the advent of formwork-free construction technologies like 3D concrete printing, evaluating early-age shrinkage in cementitious materials has become more critical. This paper reviews different test methods for assessing early-age shrinkage. These methods are classified as contact-based, which includes measurement systems that must remain in physical contact with the test specimen or embedded sensors placed inside the fresh concrete, and non-contact-based, which includes optical-based approaches either using white light (digital image correlation) or laser beams. The working principles, advantages, and challenges of the techniques, particularly while handling fresh concrete are discussed. The different mechanisms contributing to early-age shrinkage are reviewed and the common shrinkage mitigation strategies are also pointed out.