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.

This study deals first with the deterioration of glass fiber in mortar due to the alkali of cement and how to improve the deterioration of the glass fiber in mortar using special admixture of blast furnace fume (BFF). The deterioration is estimated by an accelerated test for flexural strength of mortar stored in water at 80 °C for 3 weeks. Secondly, the deterioration of mortar due to sulfuric acid attack using blast furnace fume(BFF) is investigated. Dust collected from the top of Chinese small-sized iron blast furnaces is called BFF in Japan , and is used as admixture for high strength concrete in China. BFF is composed of very fine particles with spherical shape. Its average grain size is several micrometers in diameter. Test results of this first study shows that the deterioration of glass fiber in mortar due to alkali is not improved by using BFF alone but is significantly improved by using both BFF and blast furnace slag (BFS) or silica fume (SF). Concerning acid attack, it is found that the deterioration of mortar in dilute sulfuric acid is significantly decreased by using both of BFF and BFS or SF.

Chemical attack poses a serious problem for concrete structures in severe environments. This investigation deals with exposure of high strength/high performance concrete to sulfate attack in a controlled environment. Experimental tests consisted of measuring the compressive strength, tensile strength and modulus of elasticity after 3 years of exposure to corrosive conditions consisting of chemical solutions containing 1%(NH4)2SO4 and 2%(NH4)2SO4.

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.

Ultra high strength concrete (UHSC) is undoubtedly an engineered high-tech material, which can be seen as the latest step in the concrete technology development. It is characterized by extraordinary mechanical properties, e.g. high compressive and tensile strength as well as large elastic modulus. For the development of ultra high strength concrete the compressive strength was the relevant factor, therefore suitable mixes normally contain large quantities of cement and silica fume (³ 700 kg/m³), special aggregates and chemical admixtures. Consequently the material costs of this concrete type are very high. The aim of this investigation was to develop different UHSC-mixes in order to minimize the material costs. Furthermore, normal mixing and compacting intervals were used, so that the concrete can be easily handled on site, including pumpability. This paper outlines an experimental program and its results for the development of economic mixes for UHSC. Altogether 69 different mixes were tested on the fresh and hardened properties. Especially the cement type has a significant influence on the workability and the ultimate strength. It could also be shown that a strength of 150 N/mm² can be reached with a maximum cement content of 500 kg/m³.