Assessment of Restrained Shrinkage Cracking of Concrete with Elliptical Ring Specimens – Preliminary Results

Title: Assessment of Restrained Shrinkage Cracking of Concrete with Elliptical Ring Specimens – Preliminary Results
Author(s): Xiangming Zhou, and Olayinka Oladiran
Paper category : conference
Book title: International RILEM Conference on Advances in Construction Materials Through Science and Engineering
Editor(s): Christopher Leung and K.T. WAN
ISBN: 978-2-35158-116-2
e-ISBN: 978-2-35158-117-9
Publisher: RILEM Publications SARL
Publication year: 2011
Pages: 309 - 316
Total Pages: 8
Nb references: 14
Language: English

Abstract: Cracking of concrete under restrained condition at early ages is one of the main world-wide growing concerns for concrete structures. So far it has been mainly evaluated by qualitative means through a variety of cracking tests, such as the ring, the beam, and the plate tests. It has however been found that the traditional ring test recommended by either ASTM or AASHTO has very low cracking sensitivity making it very time consuming and not efficient for large amount of materials evaluation. One the other hand, there is difficulty in providing constant and adequate restraint and end condition in the beam test, as recommended by RELIM. This study will introduce a new cracking test method by using the proposed elliptical ring specimen to assess the cracking potential of concrete as well as the sensitivity of the steel ring. Shrinkage reducing admixture (SRA) has been found to be able to reduce free shrinkage of concrete. Results presented in this study indicate that SRA can affect concrete’s early age mechanical properties such as compression and tensile strength. Further indications provide evidence that SRA is shown to have a retarding effect in concrete if allowed to shrink without any restraint. A series of circular and elliptical ring specimens were exposed to drying environment till cracking occurred under various degrees of restraints. It has been found that the steel ring thickness is observed to be a contributing factor to the time and position of crack which highlights that specimen geometry can also influence position where cracks are expected to appear. The elliptical ring is observed to provide less restraint along the major principal axis and more restraint along the minor axis as compared to the circular ring with more uniform restraint all through the ring. Results show the influence of SRA dosage on the time of crack irrespective of the degree of restraint provided by both circular and elliptical steel rings.

Online publication: 2011-10-31
Publication type : full_text
Public price (Euros): 0.00