International Concrete Abstracts Portal

SP-228CD This CD-ROM of Special Publication 228 contains the papers presented at the Seventh International Symposium on the Utilization of High-Strength/High- Performance Concrete that was held in Washington, D.C., USA, June 20-24, 2005. The symposium continued the success of previous symposia held in Stavanger, Norway, (1987); Berkeley, California (1990); Lillehammer, Norway, (1993); Paris, France, (1996); Sandefjord, Norway, (1999); and Leipzig, Germany, (2002). The symposium brought together engineers and material scientists from around the world to discuss topics ranging from the latest applications to the most recent research on high-strength and high-performance concrete. In the years since the first symposium was held in Stavanger, there has been worldwide growth in the use of both high-strength and high-performance concrete. In addition to more research and applications of traditional types of high-performance concrete, the use of self-consolidating concrete and ultra-high-performance concrete has moved from the laboratory to practical applications. This publication offers the opportunity to learn the latest about these developments.

The Woodrow Wilson Memorial Bridge carries traffic on both I-95, the primary north-south corridor on the east coast, and I-495, the Capital beltway. In order to increase capacity and replace the rapidly deteriorating existing structure, a new bridge is currently under construction. A unique system of V-shaped piers and haunched steel girders are utilized to aesthetically provide an arch shaped appearance. The bridge foundations, V-piers, bascule piers, abutments and deck slab will be constructed using high performance concrete. A discussion of the various admixtures used in the concrete mix to provide a durable concrete that minimizes cracking and chloride intrusion into the concrete will be presented.

The New York State Department of Transportation (NYSDOT) has been using High Strength High Performance Concrete (HSHPC) for prestressed concrete bridge beams for a few years on a limited basis. Based on the overall success of projects (23 bridges) during the 2001-2003 period, the Department is currently specifying HSHPC for all prestressed concrete bridge beams. This paper is intended to convey the New York experience in this area to other bridge owners. This paper includes a brief history of use of HSHPC in NYSDOT bridges, an explanation of why NYSDOT decided to go 100% HSHPC for bridge beams and a cost comparison between HSHPC beams and conventional concrete beams. A brief discussion of the current HSHPC Specifications, use of pre-approved HSHPC mix proportions by precasters producing bridge beams for NYSDOT, the approval process for mix proportions by precasters and quality control tests during production of HSHPC beams has also been included. Based on the New York experience, use of HSHPC is providing great value for bridge owners, especially in areas where corrosion of embedded steel is a problem due to exposure to chlorides.

Two-point loading tests were conducted to examine the shear and flexural behavior of High Strength Steel Fiber Reinforced Concrete (HSFRC) elements with a minimum amount of reinforcement. In shear, considerations of the ratio between the capacity that is required of the minimum shear reinforcement and the concrete shear capacity Vc show that the requirement for minimum reinforcement may depend on the definition of Vc, i.e., whether it is that of the plain concrete or that of a concrete mix, which includes the fibers. In flexure, the addition of fibers to flexural members with a minimum longitudinal reinforcement caused in the current study a more brittle behavior compared to the same specimens, which did not include fibers. This result suggests that the minimum longitudinal reinforcement ratio in flexural HSFRC members should be higher than in conventionally reinforced members (i.e., without fibers) in order to achieve sufficient ductility.

To improve the toughness and shear resistance of high strength concrete, steel fiber was induced into the reinforced high strength concrete beams. 39 steel fiber reinforced high strength concrete (fcu=52.4~84.7MPa) beams with stirrups and 5 control beams were tested. The test program was divided into two series. One series was tested under two symmetrical point loads, and the other was tested under an equivalent uniformly distributed load simulated by eight symmetrical point loads. The main variables were steel fiber volume fraction, steel fiber type, stirrup content and concrete strength. The test results showed that deformation properties, diagonal cracking strength and shear strength of the beams were improved significantly by the addition of steel fibers. Based on the test results, some empirical formulas are given to predict the diagonal cracking strength and shear strength of steel fiber reinforced high strength concrete beams. Results are also coordinated with those for reinforced concrete beams.