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 Montana Department of Transportation (MDT) is performing research to develop a cost-effective, indigenous high-performance concrete (HPC) for use in bridge deck applications. The investigation was divided into two tasks: 1) identification of the optimum cementitious matrix for the HPC and 2) evaluation of the performance of this matrix in combination with aggregates readily available in Montana. The work focused on the use of binary, ternary, and quaternary blends of portland cement with fly ash (Class C and F), slag, calcined clay, metakaolin, and silica fume, in combination with Yellowstone River and Western Montana aggregate sources. Testing included plastic properties, setting characteristics, air-void system parameters, electrical conductivity, strength, chloride diffusion, freezing and thawing resistance, scaling resistance, and drying shrinkage. The paper discusses the process required to test and implement HPC specifically for bridge deck applications and presents the test results for this MDT study. The supplementary cementitious material combinations that produced the best performance were silica fume alone, silica fume and slag, Class F fly ash, silica fume and slag-blended cement, and silica fume and calcined clay-blended cement. The importance of raw material testing and the practical reproducibility of the concrete mixture are also considered.

High Reactivity Metakaolin (HRM) is an engineered pozzolanic mineral admixture, reacting aggressively with calcium hydroxide which results in significant performance of concrete. HRM has been introduced to be a beneficial alternative for silica fume, required in the formulation of high strength/performance concrete. In this study, different aspects of concrete mechanical behaviors have been studied including compressive, flexural and splitting tensile strengths. Also some characteristics of concrete durability were investigated including water absorption, water penetration and gas permeability. In mixture proportioning, 5%, 10% and 15% of cement content is replaced by HRM or silica fume for comparative study. It was observed that both concrete with HRM and silica fume would perform almost the same in improving the mechanical properties of the materials. However in the case of workability and durability, a better performance was obtained in concrete with HRM. It was concluded from the investigation that HRM could be an appropriate substitute for silica fume in producing high performance concrete.

As with other mineral admixtures, the use of rice-husk ash leads to an improvement of the concrete internal structure, reducing the pore size and particularly an improvement in the interface bond. In this sense it can be assumed that the failure mechanism can be modified, and the concrete will exhibit a more brittle behavior. That has a special interest in high-strength concrete and in the design of large concrete structures. This paper focuses on the fracture behavior of rice-husk ash concrete. A wide range of concrete strengths are analyzed including normal and high-strength mixtures. The flexural behavior was analyzed following the general guidelines of the RILEM 50-FMC using a center-point loading arrangement on notched beams of 400 mm span, measuring deflections and the crack mouth opening displacement (CMOD). In addition, the compressive strength and the elastic modulus were measured on standard cylinders. The effects of water-cementitious material ratio and the age of testing on the strength, energy of fracture and the characteristic length on concretes with and without rice-husk ash incorporation are discussed.

Prestress loss estimation is required for properly assessing concrete stresses and member deformation. Earlier methods of prestress loss prediction were based on relatively low concrete strength. Their use for high strength concrete can produce significant errors due to their inability to accommodate varying material properties. Another source of error for earlier methods is that they do not adequately address the interaction between precast concrete members and cast-in-place composite topping. This paper presents the results of the research work conducted by Tadros et al.1 in the National Cooperative Highway Research Program (NCHRP) 18-07 study on prestress losses in high strength concrete which have been adopted by the American Association of State Highway and Transportation Officials, Load and Resistance Factor Design, AASHTO LRFD Specifications2 for inclusion in the 2005 Edition. This paper consists of two parts. Part I describes the development of the new methods that are applicable to conventional and high strength concrete ranging from 4 to 15 ksi (28 to 103 MPa). Part II deals with the experimental program and comparison of measured versus estimated prestress losses.