Risk of blocking for self-compacting concrete

Author(s): A. Gram
Paper category: Symposium
Book title: 3rd International RILEM Symposium on Rheology of Cement Suspensions such as Fresh Concrete
Editor(s): O.H. Wallevik, S. Kubens, S. Oesterheld
ISBN: 978-2-35158-091-2
e-ISBN: 978-2-35158-092-9
Pages: 143 - 147
Total Pages: 5
Language: English

Abstract: 
With the increasing complexity of concrete structures, blocking of the concrete may cause incomplete form filling. Some of the parameters governing passing ability of Self-Compacting Concrete, SCC, are the geometry of the form and spacing of rebars as well as the SCC mix design with its resistance to segregation, the grading curve of the aggregates, maximum aggregate size, aggregate shape and texture. Blocking between rebars or in a confinement of the formwork is caused either by too high apparent viscosity of the concrete or by grains in the concrete that form an arch that congests the flow. A high ratio of maximum aggregate size compared to minimum clear spacing in the form will render a higher risk of granular blocking, since less grains are needed to form the bridge. This risk is also increased for aggregates of angular shapes and a rough surface, as is the case with crushed rock. The risk of blocking, or jamming of particles, should be zero in order to completely ensure the passing of rebars. Incomplete form filling due to high apparent viscosity may be simulated numerically with applications available to date.

Online publication: 2009
Publication Type: full_text
Public price (Euros): 0.00