Title: Overview of Anchorage Problems of Reinforcing Bars in High-Performance Silica Fume Concrete
Author(s): B. S. Hamad
Publication: Symposium Paper
Appears on pages(s): 847-870
Keywords: bond; concrete (high-performance); silica fume
Production of high performance concrete (HPC) depends on several factors including the use of low water-to-cementitious material ratio, proper dosage of high-range water-reducer (superplasticizer), and a careful selection and dosage of a mineral pozzolanic admixture such as silica fume. Most of the improvement in the strength and durability characteristics of the hardened concrete is attributed to the filler effect and pozzolanic action of the fine size silica fume. Results of tests conducted at the American University of Beirut (AUB) on tension lap splices in full-scale beam specimens and on reinforcing bars anchored in eccentric pullout specimens, indicate that the replacement of part of the cement by an equal weight of silica fume resulted in reduction in bond strength. The reduction was independent of specimen type, bar size, super-plasticizer dosage, and casting position. The mode of failure of the high strength concrete beam specimens was a very brittle bond splitting failure. Tests were conducted to check the effect of transverse reinforcement in the splice region on the bond strength and mode of failure. This paper will provide an overview of the research performed at AUB.