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.

Ultra-high performance, fiber reinforced concrete (UBPFRC) differs from high-performance and very-high-performance concretes by the systematic use of fibers, which ensures that the material is not brittle and modifies the conventional requirements for passive and/or active reinforcement. It is well known that several concrete properties can be improved by the addition of steel fibers. The aim of this work was to study the fatigue behaviour of UBPFRC. Two Ductal® formulas were subjected to pre-cracking under static flexural loading, then fatigue flexural loading. Deflection and crack opening displacement were measured. Bending static tests were carried out on samples subjected and non-subjected to fatigue tests in order to evaluate the influence of fatigue on mechanical properties. The samples were subjected to a load level corresponding to 90% of the first crack strength for up to approximately 106 cycles. Even after more than 1 million cycles, there was still very little damage evolution and the fatigue loading had no effect on the overall mechanical behaviour. Results are analysed in terms of structural design and at the scale of the material. It is concluded that the actual French Recommendations for UBPFRC are safe for fatigue design. In addition, a reverse analysis was used to determine the endurance level of Ductal® in terms of equivalent pure fatigue tension.

This paper represents the results of an extensive experimental program that was carried out on steel fibre high strength concrete. The influence of volumetric ratio of fibre (Vf) on the different structural properties of steel fibre high strength concrete is investigated in this study. The properties include compressive strength, splitting tensile strength, stress-strain behavior, and modulus of elasticity. Control mixes of plain concrete that cover a wide range of high strength concrete, specifically from 40 MPa up to 80 MPa specified strengths, are first prepared. Then, steel fibres of different volumetric ratios ( 0.5 %, 0.75 %, 1.0 %, and 1.5 %) were used with the control mixes to establish their effect on the structural properties. The results showed that the addition of steel fibres to the concrete mix of high strength concrete enhanced the different properties especially splitting tensile strength and stress-strain behavior. The performance proved to be better for higher volumetric ratio of the steel fibre. Regression analyses are carried out and derived relations for different structural properties are compared with those in the ACI Codes.

Construction of modern structures and reconstruction of the existing onesimpose very demanding requirements for the quality of used materials. Highperformance hybrid fibre reinforced concrete appears to be a material of great importance in the future. An innovative type of this concrete was tested and its properties were compared with those of reactive powder concrete, high performanceconcrete and plain concrete. Compressive strength, flexural strength, toughness and modulus of elasticity were measured. For the purposes of toughness testing, an acousticemission technique was used to detect cracking and fracture properties.

Several years ago, a new generation of concrete, the ultra high performance fibre-reinforced concretes have been introduced. We have developed a range of products based on such new technology. The ultra high performance concrete developed is the result of an optimisation of the nature and the composition of different raw materials. It is composed of a premix, a new superplasticizer, fibres and water. Otherwise, numerous investigations have been carried out on this ultra high performance concrete such as plasticity, workability time, compressive strength, flexural strength, shrinkage, coating system, bonding, …. The ultra high performance concrete described in this paper was used for the carrying out of the tollgate roof of the viaduct at Millau, Southern France. This structure is part of the A75 motorway from Clermont-Ferrand to Montpellier.