Investigation of autogenous deformation in self-compacting concrete

Title: Investigation of autogenous deformation in self-compacting concrete
Author(s): Oskar Esping
Paper category : conference
Book title: International RILEM Conference on Volume Changes of Hardening Concrete: Testing and Mitigation
Editor(s): O. M. Jensen, P. Lura, K. Kovler
Print-ISBN: 2-35158-004-4
e-ISBN: 2351580052
Publisher: RILEM Publications SARL
Publication year: 2006
Pages: 273 - 282
Total Pages: 10
Nb references: 17
Language: English

Abstract: For modern concretes, such as high-strength and self-compacting concrete (SCC), increased amount of fines and binder content are a common explanation for the large autogenous shrinkage and early-age cracking. In order to investigate the influence of fineness of concrete constituents on autogenous shrinkage, tests with SCC, incorporating limestone fillers with different specific surface area (by BET), were conducted. A dilatometer was used, generating measures of linear autogenous (sealed) deformation of the concrete cast in vapourproof flexible tube mould. Temperature and pore pressure were simultaneously measured with the deformation. Tests were conducted on mixes both with and without cement, i.e. with and without chemical shrinkage. The results indicated that increased surface area generated an increased magnitude and rate of autogenous shrinkage, without influencing the times to initial and final set. The mixes without cement appeared to generate a large “autogenous” shrinkage, without the presence of chemical reaction of cement and water (hydration). The shrinkage was approximately 0.8 mm/m at 24 hours, after an initial swelling up to 4 hours. This is the same magnitude as for the mixes with cement, but then these mixes generated no swelling and almost all shrinkage before final set (at ~11.5 hours from mixing). Increased particle surface area also decreased the rate and magnitude of evaporation, and consequently reduced the plastic crack tendency, despite increased autogenous shrinkage. Adding extra water to the mix, compensating for the loss of flowability due to increased particle surface area, increased the crack tendency significantly.

Online publication: 2006-07-30
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2351580052.029