Title:
Bond Characteristics of High-Strength Lightweight Concrete
Author(s):
David W. Mitchell and H. Marzouk
Publication:
Structural Journal
Volume:
104
Issue:
1
Appears on pages(s):
22-29
Keywords:
bond; high-strength concrete; lightweight aggregate
DOI:
10.14359/18429
Date:
1/1/2007
Abstract:
Future construction of concrete floating platforms for offshore oil exploration off the east coast of Canada will lead to a substantial increase in the use of high-strength lightweight (HSLW) concrete. HSLW concrete has been extensively used in Norway and other parts of Europe. HSLW concrete with its high durability and lightweight characteristics is a very much sought after material in the construction of concrete floating platforms. The main objective of this investigation is to determine the bond strength characteristics of HSLW concrete. The experimental program consisted of testing 72 pull-out and push-in specimens to evaluate the bond behavior under monotonic and cyclic loading using 25 and 35 mm (No. 8 and No. 11) deformed reinforcement embedded in high strength of 80 MPa (11.6 ksi) lightweight concrete. The static and cyclic test results indicated that HSLW concrete behaves very similar to high strength normalweight concrete. The bond strength of HSLW was equal to or slightly larger than similar specimens made of high strength normalweight concrete (HSNW) at the same lab. The bond stress versus displacement curve indicated a sharp linear ascending portion followed by a steep descending portion indicating a brittle failure, which is characteristic of high-strength concrete. The ACI 318 code increases the minimum development length of lightweight concrete by 30%. The ACI recommendation of this increase is unjustified for high-strength concrete made of lightweight aggregates.