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.

In order to decrease cross sectional area of structural members, ultra high strength concrete with compressive strength over 150 MPa is required for building structural members, which needs no steam curing. In the present study, concrete is made of silica fume cement which is composed of low heat type cement and silica fume and demonstrates high compactability. Compressive strength of the concrete with water to binder ratio of 0.15 and the effect of hydration heat of binder on compressive strength are investigated experimentally. Effectiveness of expansive additive on reduction of autogenous shrinkage is also investigated. According to the experiment, compressive strength over 150 MPa is gained by adopting appropriate aggregates without steam curing at early ages, while the strength of full sized specimens decreased about 10 % at the age of 91 days. Autogenous shrinkage was reduced from more than 700x10-6 to 0 by expansive additive and shrinkage-reducing admixture. However, expansive additive leads to strength reduction of about 10 %.

This report presents the results of an experimental program dealing with ultra high strength concrete (UHSC) under concentrated load. The implemented tests should be used for the determination of the bearing capacity under concentrated load and for the observation of the failure behavior. Specimens made of plain and reinforced concrete were tested, whereby a helical reinforcement was used. The results were compared with an extrapolation of existing design rules established for normal and high strength concrete. In this context, two different UHSC and one high strength concrete for comparison were investigated in order to recognize the influence of concrete strength and composition on the load bearing behavior under concentrated load. The results showed that the bearable concentrated load depends on the compressive strength and also on the concrete composition. Furthermore the under-proportional increase of the tensile strength in relation to the compressive strength has an important influence on the bearing behavior of UHSC.

As a part of a research program on development and evaluations of high-performance concrete (HPC) for the state of West Virginia, in this study sixteen HPC mixtures were produced using two types of locally available 25 mm graded limestones, gravels, and one type of river sand. For each type of aggregate, four kinds of HPC were developed by using the following mineral admixtures: (1) 10% metakaolin; (2) 20% fly ash and 5% silica fume; (3) 30% slag and 5% silica fume; and (4) 15% fly ash, 25% slag and 5% silica fume. A constant water-cementitious material ratio of 0.4 and aggregate-paste volume ratio were maintained for all mixtures. In addition to basic fresh properties, compressive strengths at 1, 3, 7, 14, 28 and 90 days, 28-day modulus of elasticity (secant and dynamic) were measured. Preliminary data show that metakaolin HPC achieved the highest strengths, particularly at ages up to 28 days, followed by slag-silica fume HPC, fly ash- silica fume HPC and fly ash-slag-silica fume HPC. At 90 days both metakaolin HPC and slag-silica fume HPC achieved almost the same range of strengths. Overall, limestones performed better than gravels in terms of both strength and moduli of elasticity. Modified empirical relations between compressive strength and static modulus, and dynamic modulus and static modulus are proposed. Since the expressions are based on a large number of specimens for both limestone and gravel mixtures, including different types and dosage of mineral admixture, the results can be used for prediction of HPC of similar strength and materials.

Since the 1970’s the concrete industry has seen major developments in high strength/ high-performance concrete (HPC). New materials, design codes and construction methods have enabled us to design and build taller, slimmer, lighter, more attractive and more durable concrete structures. Through research and development and practical applications we have improved our knowledge on strength, ductility, durability, constructability, appearance and other properties to where technology is not the limiting factor, but rather our ability to utilize what we know and to promote our ideas for more sustainable and competitive concrete structures. HPC is now covered by a number of design codes and high-performance structures can be produced almost anywhere with selected local materials and competent workmanship. The volume of available literature on HPC has increased almost exponentially in recent years. Large research and development programmes have been executed and shown to produce remarkable results and provide very satisfactory returns on the investment. HPC still constitutes only a small part of the output of the concrete industry and is largely limited to marine structures, large span bridges and prestigious buildings and to some extent precast components. The market of ordinary structures is still dominated by ordinary concretes with ordinary performance. The paper discusses some aspects related to the evolution of high strength concrete (HSC) and high performance concrete and how the concrete industry, for the benefits of the clients and its own performance and image, needs to more actively utilize the proven HPC technology.