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.

Twenty-four unique, thin-shelled canopies measuring 5 m x 6 m and just 2 cm thick (18' x 20' and 3/4" thick) supported on single columns, protect commuters from the elements at Calgary’s new Shawnessy Light Rail Transit (LRT) Station. The innovative design was made possible with a new, ultra-high performance, fiber reinforced material that offers a combination of superior technical characteristics including ductility, strength and durability while providing highly moldable products with a quality surface. For this project, the material compressive strength was 150 MPa (22,000 psi) and flexural strength was 18 MPa (2,600 psi). The mechanical properties and design flexibility facilitated the architect’s and engineer’s ability to create the thin, curved, off-white shell structure. This paper presents the fundamentals of the technology, material properties, design details, manufacturing, prototyping, full-scale load testing, erection and economics. Many economies gained from this new technology are a result of engineering new solutions for old problems. By utilizing the material’s unique combination of superior properties, designs can eliminate passive reinforcing steel and experience reduced global construction costs, site formworks, labor and maintenance. Additional benefits include improved construction safety, speed of construction and extended usage life.

This synopsis is based on a three-part report to be published by ACI in the near future The origin of ACI’s Innovation Task Group (ITG) 4, High-Strength Concrete for Seismic Applications, can be traced back to an International Conference of Building Officials or ICBO (now International Code Council or ICC) Evaluation Report entitled “Seismic Design Utilizing High-Strength Concrete” (ER-5536). Evaluation Reports are issued by Evaluation Service subsidiaries of model code groups. An ER essentially states that although a particular method, process or product is not specifically addressed by a particular edition of a certain model code, it is in compliance with the requirements of that particular edition of that model code. ER-5536, first issued in April 2001, was generated by Englekirk Systems Development Inc. for the seismic design of moment resisting frame elements using high-strength concrete. High-strength concrete was defined as “normal-weight concrete with a design compressive strength greater than 6000 psi and up to a maximum of 12,000 psi.” It was based on research carried out at the University of Southern California and the University of California in San Diego to support building construction in Southern California using concrete with compressive strengths greater than 6000 psi. The evaluation report (ER-5536) is available on the ICC website for review. A thorough review of the above document brought up several concerns focusing on two primary areas: material and structural aspects. Irrespective of those concerns, it was evident that the evaluation report had been created because quality assurance and design provisions are needed in cities like Los Angeles to allow the use of high-strength concrete in a safe manner. Through the formation of ITG 4, ACI has assumed a proactive role in the development of such provisions with the goal of creating a document that can be adopted nationwide. The mission of ITG 4 is to develop an ACI document that addresses the application of high-strength concrete in structures located in areas of moderate and high seismicity. A structure located in an area of moderate seismicity, in modern terminology, is a structure assigned to Seismic Design Category or SDC C of the International Building Code (IBC) or the NFPA 5000 Building Construction and Safety Code. A structure located in an area of high seismicity is a structure assigned to SDC D, E, or F of the IBC or NFPA 5000. The document is to cover structural design, material properties, construction procedures, and quality control measures. It is to be written or contain example language in a format that will allow building officials to approve the use of high-strength concrete on projects that are being constructed under the provisions of ACI 301 Specifications for Structural Concrete and ACI 318 Building Code Requirements for Structural Concrete. The ITG 4 document, now in draft form, addresses the material and structural design considerations when using concretes having specified compressive strengths of 5000 psi (34 MPa) or greater that must be designed considering moderate to high seismic risk. The term “high-strength concrete,” as defined by ACI Committee 363, refers to concrete having a specified compressive strength for design of 8000 psi (55 MPa), or greater. As such, this document is meant primarily for concretes in that high strength range. However, the strength level at which concrete is considered “high-strength” depends on regional factors, such as the characteristics and availability of raw materials, production capabilities, testing capabilities, and lastly, experience. Therefore, depending on the region, the specifier may wish to selectively adopt considerations referenced in this document also when using concretes with specified compressive strengths between 5000 and 8000 psi (34 and 55 MPa). Irrespective of the location or purpose for which it is used, concrete having specified compressive strength below 5000 psi (34 M

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.

The effect of air entrainment on the compressive strength of high performance concrete is presented in this paper. Generally, an increase in the total air content of one percent decreases the compressive strength of concrete two to five percent. This rule of thumb was developed from research on normal strength concrete, but there is little data on the strength reduction due to entrained air in high performance concrete. The paper presents compressive strength test results of several high performance concrete mixtures with total air contents ranging from two to six percent. The compressive strength of the mixtures varied from 42.4 MPa (6150 psi) to 95.9 MPa (13,900 psi). The results of the study support the use of this rule of thumb for high performance concrete. Data are also presented on the increased dosage rate of air entraining agents required in low water to cementitious material ratio concrete.