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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
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| This report is an archived publication and may contain dated technical, contact, and link information |
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Publication Number: FHWA-RD-97-030
Date: 1989-1994 |
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High-Performance ConcretesA State-of-Art Report (1989-1994)7 RECENT ACTIVITIES OF ORGANIZED PROGRAMS ON HPC 7.1 Introduction Although the concept of high performance concrete as a technology emerged out of laboratory no more than 15 years ago, it has since experienced a phenomenal growth in research and application worldwide during the past decade. While published reports on the subject were rare in the beginning of the 1980's, no one is able to cope with the massive stream of information today. This extraordinary expansion of activities is due in large measure to the stimulus provided by a number of national organized programs to advance the technology in response to need for the massive civil infrastructure renewal and construction around the world. Notable among these national efforts are those of Canada, France, Japan, Norway, and the United States. This chapter will provide an overview of the recent activities of a number of nationally organized programs on high performance concrete. 7.2 Canada In 1990, the Canadian government created a unique Network of Centers of Excellence on High-Performance Concrete with a 4-year funding of $6.4 million. The Network included seven universities and two industrial partners with its administrative headquarters being located at the University of Sherbrooke. Roughly two-thirds of this organized research effort were focused on materials studies and one-third on structural investigations. Research topics included selection of constituent materials for HPC, durability, evaluation of standard test procedures, nondestructive tests, fiber reinforced shotcrete, bond and anchorage, shear strength, and the use of high strength reinforcement [MacGregor 1993]. The Network made significant advances in the areas of materials improvement, structural design, placing and construction techniques. Methods for producing ready-mixed HPC with compressive strength up to 120 MPa (17,400 psi) were developed in several regions of Canada. Based on the success of the first 4-year effort, the Network – now named Concrete Canada – received from the Canadian government a renewal grant of $5.5 million in 1994. The second 4-year research program of Concrete Canada focuses on four general areas: infrastructure rehabilitation, durability, cost effectiveness of HPC structures, and the development of new materials and products. In the area of new materials, Concrete Canada participated in the development of what is known as Reactive Powder Concrete (RPC), in which coarse aggregates and sand are replaced by powders with carefully selected grain-size distribution. Using this technology, concretes with more ductility can be produced for compressive strengths ranging from 200 to 800 MPa (29,000 to 116,000 psi), flexural strengths from 30 to 65 MPa (4,350 to 9,400 psi), and toughness varying from 20,000 to 60,000 J/m2 (0.44 to 1.33 kCal/ft2). These concretes are virtually impermeable and show excellent freez-thaw as well as abrasion resistance. A vital component of Concrete Canada is its primary commitment to transfer the new technology to the construction industry to enhance its competitiveness. In this effort, Concrete Canada engages 17 Principal Researchers and 29 Collaborating Investigators, working in conjunction with over 60 partner organizations and affiliate member. The following are some examples of technology transfer for HPC in Canada [Concrete Canada 1995]:
7.3 China The first application of high-strength concrete in China occurred in the late 1970's when a large arch-type blast door for a naval vessel storage was constructed using concrete with compressive strength of 70 to 75 MPa (10,000 to 10,700 psi). At the same time, a cable-stayed railway bridge across the Red Water River in Guangxi Province was constructed with 60 MPa (8,700 psi) pumped concrete for its three-span (48 + 96 + 48m or 157.5 + 315 + 157.5 ft) prestressed box-section girders. Since then, the use of HSC has expanded rapidly. No less than 20 high-rise buildings in major cities and 13 major highway or railway bridges at strategic locations across the country have been constructed using concrete with compressive strength varying between 50 MPa (7,250 psi) and 80 MPa (11,600 psi), mostly at 60 MPa (8,700 psi). A major 5-year (1987-1991) research program on HSC was supported by the National Natural Science Foundation of China (NNSFC) and the State Ministry of Construction, and was completed by close collaboration among the universities, research institutes, and construction corporations. Based on the research, a "Design Guide for HSC Structures" was compiled in 1993. Beginning in 1994, a new organized research program on C50 – C100 (7,250 – 14,500 psi) HPC is in progress with joint support of the NNSFC, the State Ministry of Railway, the State Ministry of Construction, and the State Bureau of Building Materials. The emphasis of the program is on long-term behavior of HSC materials and members [Chen and Wang 1996] 7.4 Denmark The Danish research program "High Performance Concretes in the 90's" is financed by the Danish government and carried out in cooperation between the Technical University of Denmark, several private companies, and Aalborg University. The research has focused on the mix design, uni- and triaxial strength, creep, shrinkage and chloride diffusion of HPC. Applications of HPC have included several relatively short span bridges to obtain knowledge on the full scale performance with respect of the structural behavior and the durability characteristics. This knowledge has been utilized in the design of two major infrastructure projects — the Great Belt Link and the Oresund Link — which are under construction [Nielsen et al. 1996]. 7.5 France Based on the recommendations of a 1985 white paper presented by the National Steering Committee for research in civil engineering, the six-year French National Project on "New Ways for Concrete" was created in 1986 by thirty partners from industry and research institutes with the support of the French Ministry of Public Works and the French Electricity Board. The objective of the Project was to explore and develop new concepts and methods for utilizing high performance concrete by following four basic principles:
The first achievement of this Project was the construction of the Joigny Bridge using 60 MPa (8,600 psi) concrete as described previously in Section 6.2.2. Instrumentation installed in the bridge was monitored to evaluate creep and shrinkage of the bridge. Additional applications of HPC included bridges, buildings, offshore oil platform, barge and tunnel, and nuclear containment vessels, etc. These applications have been described recently by Cheyrezy [1996], Monachon and Gaumy [1996], and Dugat et al. [1996]. Another significant contribution of the Project is the publication of an authoritative treatise on high performance concrete edited by Yves Malier [1992]. 7.6 Japan A five-year research program entitled "Development of Advanced Reinforced Concrete Buildings Using High-Strength Concrete and Reinforcement" was organized by the Japanese Ministry of Construction in 1988. Concrete strengths ranging from 30 to 120 MPa (4,350 to 17,400 psi) were considered along with the strength of reinforcing bars ranging from 400 to 1,200 MPa (58,000 to 174,000 psi). Research studies covered the development of constituent materials for high strength concretes and the determination of their physical properties. In addition, the program also included the development of high strength steel bars, the determination of the mechanical properties of the steel bars and their bond with high strength concrete, structural behavior of beams and columns made with such high-strength materials, as well as structural design methodology including seismic design [Aoyama et al. 1990; Kaku et al. 1992]. Almost concurrent with this major research and development program is the development of "self-compactable" or "flowable" high performance concrete with close cooperation among universities and industry. The primary motivation for the development is to minimize the manual handling of concrete on the job site (to overcome shortage of skilled labor force) with the ultimate goal of achieving automation of concrete construction. An excellent report describing this development has been presented by Okamura and Ozawa [1994]. 7.7 Norway The Norwegain national research program on high performance concrete has been supported by the Royal Norwegian Council for Scientific and Industrial Research (NTNF) and the concrete industry. The program includes research on concrete mix design, durability, mechanical properties, flexural and shear capacities, and fatigue behavior. Some results from this research have been introduced into the revised Norwegian Standard NS 3473 [Jensen 1990]. More recent research activities have focused on early-age cracking, pore structure, and durability of high performance concrete [Sellevold 1996]. There have been four international symposia on the utilization of high strength/high performance concrete, and Norway has hosted the first and the third symposia. 7.8 Sweden In Sweden, a six-year organized research program on high performance concrete was initiated in 1991. The total budget for the program is at the level of $6.6 million or $1.1 million per year. Funds are provided jointly by a consortium of six companies (Cementa, Elkem Materials, Euroc Beton, NCC, SKANSKA, and Strangbetong) and two government agencies (NUTEK and BFR)on a 50/50 basis. 75% of the budget is allocated to research performed at six universities, one research institute, and one private research unit, the remaining 25% of the budget is allocated to work done by R & D personnel of the industrial partners. The objectives of the program are two-fold: (1) to increase the basic knowledge in selected areas of HPC and therby to create a competent staff of R & D personnel, and (2) to adapt and translate research findings in Sweden and elsewhere into recommendations and guidelines for use by the industry in their own product and process development. The program focuses on three general areas: materials, production technique, and structures. In each of these areas, five to seven specific research topics are pursued. The major concerns are mix design, workability, curing, durability, cracking, bond, toughness, and fatigue. A comprehensive summary of the research program has been presented by Elfgren et al. [1996] 7.9 United States In the United States, research and development of HPC has been conducted by several nationally organized programs and government laboratories. In addition, several universities are also involved substantially in HPC research, generally with joint support of the Federal, State and private sectors. Presented below is an overview of the major activities. It is not intended to be a comprehensive survey. 7.9.1 ACBM A unique Center of Excellence for Science and Technology of Advanced Cement-Based Materials (ACBM) was established by the National Science Foundation at Northwestern University in 1989. The Center is a research consortium made up of four universities (Northwestern, Illinois, Michigan, and Purdue) and the National Institute of Standards and Technology (NIST). The primary mission of the Center is to engaged in basic research to develop and transfer knowledge needed to understand the family of complex cement-based materials. ACBM's activities fall in three program areas: research, education and training, and technology transfer. Now in its 7th year of operation, ACBM's research projects are organized into five key theme areas: Processing, Interfaces, Microstructural Characterization, Transport Phenomena, and Toughening Mechanism. Five or six projects are pursued in each of the theme areas. The issues addressed in these projects are to identify the chemical and physical phenomena that influence the microstructure development, to develop new techniques to characterize microstructure, to define relationships between microstructure and bulk material properties, and to explore methods to modify the matrix to yield tougher, more durable cement-based materials. The Center's objectives are "not only to improve the performance and predictability of high performance concrete through the application of science and technology, but also to develop novel cement-based materials with targeted properties" [ACBM 1995]. A summary of ACBM's activities has been presented by Shah [1996] Although ACBM conducts basic research for the most part, it is also engaged in applied research through its Industrial Affiliate program. The recent development of a patented extrusion technology to produce cement-based matrix with large volumes (2 to 8%) of discontinuous fibers [Shah 1996] and the announcement of a new Shrinkage Reducing Admixture [Northwestern News 1966] are but two examples of this activity. 7.9.2 SHRP The Strategic Highway Research Program (SHRP) was a 5-year , nationally coordinated research effort initiated in 1987 at a cost of $150 million. One of the four program areas of SHRP was Concrete and Structures for which funding was budgeted at approximately $18 million. Within the program area of Concrete and Structures, SHRP C-205 on Mechanical Behavior of High Performance Concrete was a 4-year (1989-1993) project conducted by a consortium among researchers at North Carolina State University, the University of Arkansas, and the University of Michigan with a budget of $2 million. Three types of high performance concrete — very early strength (VES), high early strength (HES), and very high strength (VHS) — were developed using four different types of coarse aggregate. A variety of properties of the fresh and hardened concretes related to workability, strength, and durability were determined, and field installations of VES and HES pavements were implemented in five states (Arkansas, Illinois, Nebraska, New York, and North Carolina). The research results were presented in a series of six reports. [Zia et al. 1993a, 1993b, 1993c, 1993d, 1993e; Naaman et al. 1993]. In addition, an annotated bibliography [Leming et al. 1990] and a state-of-the-art report [Zia et al. 1991] were also prepared. Other SHRP projects related to high performance concrete are the field studies conducted under SHRP C-206 [Nagi and Whiting 1994], the development of HYCON expert system [Clifton and Kaetzel 1994], and the study of resistance of concrete to freezing and thawing [Janssen and Snyder 1994] 7.9.3 NIST As a member of the research consortium of ACBM, the National Institute of Standards and Technology (NIST) established the Cementitious Materials Modelling Laboratory (CMML) in 1989. The Laboratory is staffed by members of the Inorganic Building Materials Group of NIST's Building Materials Division and visiting personnel from other organizations. The goal of the Laboratory is to develop computer models which will simulate the physical, chemical, and mechanical behavior of concrete and other cementitious materials, thereby gaining insight into factors that affect their engineering performance. Combining such models with other computer-based representations of knowledge will ultimately provide the technical basis and tools for optimum design of high-performance concretes and other new cementitious materials. To model the behavior of portland cement paste, two- and three-dimensional models at the nanometer to micrometer levels have been developed to simulate the hydration reactions occurring between anhydrous cement particles and water and the models have been used to study the phenomena of setting and diffusivity [Bentz et al. 1996]. As mentioned previously, the CMML has also developed under the sponsorship of SHRP an expert system "HYCON" as a diagnostic tool for identifying likely causes of distress in highway pavements and bridge structures [Clifton and Kaetzel 1994]. In addition, NIST in a joint effort with the National Aggregates Association/National Ready Mixed Concrete Association investigated the effects of testing variables (end preparation, cylinder size, type of test machine and testing speed) on the strength of high strength concrete cylinders [Carino et al. 1994]. 7.9.4 FHWA Federal Highway Administration (FHWA) has been engaged in research and technology transfer of high performance concrete. In a multi-year study of development length of uncoated and epoxy-coated prestressing strands at its Turner-Fairbank Highway Research Center, tranfer and development lengths of the types of strands would be determined with full-sized prestressed concrete girders using 10,000 psi (69 MPa) high strength concrete [Lane and Podolny 1993]. To transfer the HPC technology generated from the SHRP projects, FHWA has initiated a major effort in cooperation with the state highway agencies to construct demonstration bridges and to present showcase workshop to promulgate the experience gained from the demonstration projects [Vanikar and Goodspeed 1996]. The details of the demonstration bridges in the states of Texas, Virginia, Nebraska, and New Hampshire are described by Duwadi, Lane, and Berley [1996]. Several other states including Georgia, Oregon, Washington, and North Carolina are expected soon to participate in the demonstration program. 7.9.5 WES The mission of the U. S. Army Corps of Engineers Waterways Experiment Station (WES) is to serve the needs of the U. S. armed forces, the Army civil works program, and other agencies of the U. S. government. In its role in research and development in concrete technology, WES has had a long history of developing high-performance concrete to serve some specific purpose for which ordinary concrete was not adequate. These developments include tremie concrete for underwater construction, high-performance mass concrete for dams, high strength concrete (up to 223 MPa or 32,300 psi) for hardened military facilities, high-strength and high-density concrete for biological shielding from ionizing radiation, high-performance concretes for nuclear weapons testing and nuclear waste isolation, and high-abrasion-resistant and washout-resisting concretes for repair of abrasion-erosion damage under water to stilling basins below dams. Detailed descriptions of these developments have been provided by Mather [1996]. More recently, through its Construction Productivity Advancement Program (CPAR), WES has been engaged with private industries in several research and development projects in high-performance cementitious materials. In April 1994, WES completed a study on the performance of concretes proportioned with Pyrament Blended Cement [Husbands et al. 1994]. Then, at the request of FHWA, WES conducted a preliminary investigation of a newly developed cementitious material from Ash Bonding Chemicals (ABC) Corporation. The ABC cement is a high-early strength, blended hydraulic cement containing 77 to 95 percent Class C fly ash by weight. The remaining material can be slag and/or portland cement. Four readily available chemical admixtures are used in small quantities to control the workability and setting time of the material. They are a set-suspending agent, an activator, a modifying retarder, and an accelerator. The performance of the concrete produced with ABC cement was compared with the performance of concrete using Type III cement. The results indicated the ABC cement as a possible alternative to Type III portland cement for producing high-early strength concrete. The concrete produced with the ABC cement has an advantage of being able to adjust the setting time of the concrete to whatever is appropriate for a given application, low to very low chloride permeability, good frost resistance even with low air contents, minimal shrinkage at early ages. However, there was more variation in the slump and air contents for the mixtures produced with the ABC cement. The performance of the concrete also varied with the type of fly ash used and with the application of the four chemical admixtures. Therefore a more comprehensive research program has been recommended in order to fully exploit the potentials of ABC cement [Neeley 1995]. WES also collaborated with Master Builders, Inc. to test an admixture system that will enable a concrete producer to tailor the working time of fresh concrete for particular applications and ambient conditions. The research evaluated DELVO stabilizer and activator for standard ready-mixed concrete applications, including long-haul, same-day, and overnight stabilization. In addition, WES is working with HDR Engineering, Inc. to develop very high-performance concretes using reactive-powder concretes (RPC). Concretes with strengths 10 to 35 times that of conventional concrete can be produced with vastly improved material properties. Use of RPC for precast concrete products is being investigated. Furthermore, WES and 3M Corporation are jointly developing and testing a new fiber-delivery system that will allow greater volumes of inexpensive polymer fibers to be introduced into concrete mixtures. The increased volume of fibers will allow the polymer-fiber concrete to match properties achieved with steel fibers. The delivery system is efficient and simple [U. S. Army Corps of Engineers Waterways Experiment Station 1995] 7.9.6 Other Organizations Though not within any formally organized research programs, there are a number of other public and private institutions where subtantial research in high performance concrete is in progress. These institutions include public agencies such as Virginia Transportation Research Council, Florida Department of Transportation, North Carolina State University, University of Minnesota, University of Texas, University of Nebraska, University of Kansas, University of Southern California, and the private firm Construction Technology Laboratory. The research activities of these organizations have been covered in numerous publications described and discussed in this report. 7.10 References
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