Bond of Lightweight Aggregate Concrete Incorporating Condensed Silica Fume


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Title: Bond of Lightweight Aggregate Concrete Incorporating Condensed Silica Fume

Author(s): P. J. Robins and S. A. Austin

Publication: Special Publication

Volume: 91


Appears on pages(s): 941-958

Keywords: bond (concrete to reinforcement); bond stress; cement content; deformed reinforcement; lateral pressure; lightweight aggregate concrete; plasticizers; pullout tests; reinforcing steels; silica; stresses.

Date: 2/1/1986

Condensed silica fume, at up to 30% by weight, was used as a partial cement replacement in lightweight aggregate concrete. The results of round and deformed bar cube pull-out tests, with and without applied lateral stress, show that condensed silica fume increases ultimate bond strength and affects the mechanism of failure. The influence of condensed silica fume on bond stress of round bars was similar at all lateral stresses, producing a 50% increase at 20% by weight replacement of cement. For deformed bars the increase in bond strength was more pronounced at higher levels of lateral stress, producing increases approaching 70% at 20% silica fume content. The improvements in ultimate bond strength with condensed silica fume are shown to only partly result from the associated increases in compressive strength, the greater part resulting from the modified properties of the concrete matrix.