Restrained shrinkage behavior due to combined autogenous and thermal effects in mortars containing super absorbent polymer (SAP)

Title: Restrained shrinkage behavior due to combined autogenous and thermal effects in mortars containing super absorbent polymer (SAP)
Author(s): J.L. Schlitter, T. Barrett, J. Weiss
Paper category : conference
Book title: International RILEM Conference on Use of Superabsorbent Polymers and Other New Additives in Concrete
Editor(s): O.M. Jensen, M.T. Hasholt and S. Laustsen
Print-ISBN: 978-2-35158-104-9
e-ISBN: 978-2-35158-105-6
Publisher: RILEM Publications SARL
Publication year: 2010
Pages: 233 - 242
Total Pages: 10
Nb references: 16
Language: English

Abstract: Early age cracking has been observed to occur in concrete when it is prevented from shrinking freely. This cracking can occur more frequently in higher strength concrete due to a low water to cement ratio and an increase in the cement content. The low water to cement ratio exacerbates autogenous shrinkage while the high cement content increases both autogenous shrinkage and the potential for thermal cracking. Internal curing has been proposed as one method that can be used to reduce the potential for autogenous shrinkage cracking by providing internal reservoirs of water. Super absorbent polymers (SAP) are frequently used to absorb the water and to store that water. Several tests are frequently performed to assess the impact of materials composition on the potential for restrained shrinkage cracking [1]. The restrained ring test (ASTM C1581-09a) [2] is a simple, economical method to evaluate a concrete mixture’s susceptibility for restrained shrinkage cracking. Unfortunately, the restrained ring test only provides restraint against samples that shrink and can not be used to consider cases in which expansion occurs. Further, the conventional restrained ring test does not consider cases in which the concrete undergoes large variations in temperature since the restraint changes dimension under heating and cooling. This paper describes the use of the dual-ring test that was designed to overcome both of these limitations. In addition to assessing the autogenous shrinkage, the dual ring test can assess the influence of temperature on cracking. This paper will discuss the influence of SAP on reducing stresses that develop when autogenous shrinkage is restrained. In addition, this paper discusses the beneficial effect SAP has on reducing the potential for thermal cracking.

Online publication: 2010-10-04
Publication type : full_text
Public price (Euros): 0.00