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.

The Federal Highway Administration (FHWA) encourages the use of high performance concrete (HPC) to improve the long-term performance of the nation’s infrastructure at lower life-cycle costs. For its purposes, the FHWA uses 11 performance criteria to define high performance concrete, and it designates three levels of performance for each criterion, with Grade 3 being the most stringent. For FHWA projects, the specifier is expected to select the criteria necessary for a given element, and then select an appropriate performance grade. It’s not necessary or desirable to specify the same performance grade for all characteristics. Guide Specification for High Performance Concrete for Bridge Elements provides mandatory language that the specifier can cut and paste into project specifications, as well as guidance on what characteristics should be specified in a given case, and what criterion is needed to ensure satisfactory performance. It includes commentary that tells how to obtain the desired performance for each characteristic. In cases where two performance criteria are in conflict, the commentary advices the user how to balance conflicting requirements.

The Concrete Pavement Technology Program (CPTP) is a national program of research, development, and technology transfer sponsored by the Federal Highway Administration. The focus of the program is on implementing improved methods of designing, constructing, evaluating, maintaining, and rehabilitating portland cement concrete (PCC) pavements in order to promote cost-effective designs and long-term performance for federal-aid highways. Research is conducted to address State highway agency, FHWA, industry, and academia needs. Innovative designs and improved methods are evaluated through demonstrations and field trials of high performance concrete pavements by the various State highway agencies. An extensive implementation effort is included to encourage early adoption of promising research results.

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.

Overlay systems have been used by many states for the protection of bridge decks, but the premature delaminations and failures have been observed in many cases. A comprehensive study was recently defined to investigate overlay performance in collaboration with the West Virginia Department of Transportation-Division of Highways (WVDOH). As part of a comprehensive program, the present study is concerned with the properties of four types of overlay mixtures and the interface bond strengths between the overlays and substrate concrete. All the materials used are of interests to WVDOH. Four overlay types were: silica fume modified concrete, latex modified concrete, fiber reinforced concrete and slag modified concrete. With these overlays, statistical design of experiments were conducted for the evaluation of the influences on bond strength of four factors: aggregate types, surface preparations, use of bonding slurry, and substrate age using a recently developed direct shear test apparatus. Results show that except for bonding slurry, all the parameters had strong influence on shear bond strength. The results of this study will serve the purpose of screening and selection of overlays from a large number of variables, and will finally help to develop guidelines by WVDOH for future implementations of concrete overlays in the field.