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High-Performance Concretes

A State-of-Art Report (1989-1994)

1.  INTRODUCTION

1.1 Background

In 1989, a four-year investigation on the mechanical behavior of High-Performance concretes was initiated by the authors at North Carolina State University. The research was conducted under contract C-205 with the Strategic Highway Research Program (SHRP) which was a unit of the National Research Council. SHRP was authorized by section 128 of the Surface Transportation and Uniform Reloaction Assistance Act of 1987.

The first task of the research was to conduct an extensive literature search and review so that the existing knowledge about the mechanical properties of High-Performance concrete, with particular reference to highway applications, could be summarized and significant gaps in knowledge identified. Based on that literature search, an annotated bibliography containing 830 references published in the period of 1974-1989 was compiled and published by SHRP in 1990 as a reference document [Leming et al. 1990]. From that reference source, about 150 references were selected for critical review. The results of the review were summarized in a state-of-the-art report [Zia et al. 1991] published by SHRP in 1991.

Since the publication of these two previous documents, there has been a phenomenal increase in the development and use of High-Performance concrete. So a need exists to update the previous documents and summarize the significant developments during the past several years. This volume is a sequel to the previous state-of- the-art report and covers the six-year period from 1989 to 1994. A second annotated bibliography containing 776 references for the six-year period has also been compiled by the authors as a separate document [Zia et al. 1996].

It should be emphasized that, unless otherwise noted, much of the information contained in the previous state-of-the-art report is still current and will not be repeated in the present document. Therefore this document should be viewed as a supplement to rather than a replacement for the previous report.

1.2 Definition of High-Performance Concrete (HPC)

Any concrete which satisfies certain criteria proposed to overcome limitations of conventional concretes may be called High-Performance concrete (HPC). It may include concrete which provides either substantially improved resistance to environmental influences (durability in service) or substantially increased structural capacity while maintaining adequate durability. It may also include concrete which significantly reduces construction time to permit rapid opening or reopening of roads to traffic, without compromising long-term serviceability. Therefore it is not possible to provide a unique definition of HPC without considering the performance requirements of the intended use of the concrete.

Forster [1994] defined HPC as "a concrete made with appropriate materials combined according to a selected mix design and properly mixed, transported, placed, consolidated, and cured so that the resulting concrete will give excellent performance in the structure in which it will be exposed, and with the loads to which it will be subjected for its design life." In discussing the meaning of HPC, Aitcin and Neville [1993] stated that "in practical application of this type of concrete, the emphasis has in many cases gradually shifted from the compressive strength to other properties of the material, such as a high modulus of elasticity, high density, low permeability, and resistance to some forms of attack."

A more broad definition of HPC was adopted by the American Concrete Institute. HPC was defined as concrete which meets special performance and uniformity requirements that cannot always be achieved routinely by using only conventional materials and normal mixing, placing, and curing practices. The requirements may involve enhancements of (characteristics such as) placement and compaction without segregation, long-term mechanical properties, early-age strength, volume stability, or service life in severe environments. Concretes possessing many of these characteristics often achieve higher strength. Therefore HPC is often of high strength, but high strength concrete may not necessarily be of High-Performance.

For the purpose of the SHRP C-205 project [Zia et al. 1993], HPC was defined in terms of certain target strength and durability criteria as shown in Table 1.1. In this definition, the target minimum strength should be achieved in the specified time after water is added to the concrete mixture. The compressive strength is determined from 4 x 8-in. (100 x 200-mm) cylinders tested with neoprene caps. The water-cement ratio (W/C) is based on all cementitious materials. The minimum durability factor should be achieved after 300 cycles of freezing and thawing according to ASTM C 666 (AASHTO T 161), procedure A.

Based on the results of SHRP C-103 and SHRP C-205 research, the Federal Highway Administration (FHWA) has proposed criteria for four different performance grades of HPC [Goodspeed et al. 996]. The criteria are expressed in terms of eight performance characteristics including strength, elasticity, freezing/thawing durability, chloride permeability, abrasion resistance, scaling resistance, shrinkage, and creep as shown in Table 1.2. Depending on a specific application, a given HPC may require different grade of performance for each performance characteristics. For example, a bridge located in an urban area with moderate climate may require Grade 3 performance for strength, elasticity, shrinkage, creep, and abrasion resistance, but only Grade 1 performance for freezing/thawing durability, scaling resistance, and chloride permeability.

1.3  Scope

This report focuses on more recent information and developments on mechanical behavior of High-Performance concretes to update the previous state-of-the-art report. Included in this report are discussions regarding selection of raw materials and production techniques, behavior of both plain and fiber reinforced concretes in fresh and hardened states, and applications of High-Performance concrete.

As was the case with the previous state-of-the-art report, several types of special materials are excluded from consideration for both economic and practical reasons. They include extremely high strength concrete, rapid setting patching compunds, roller compacted concrete, lightweight concrete, sulfur concrete, high alumina cement, polymer concretes, polymer impregnated concretes, and sealed concrete.

1.4  Organization of Report

This report contains eight chapters. Following this introductory chapter, a discussion on materials selections and production techniques for HPC is presented in Chapter 2. Chapter 3 describes the properties and behavior of HPC in its fresh state, followed by discussions of the behavior of HPC in its hardened state in Chapter 4. Behavior and applications of High-Performance fiber reinforced concrete (HPFRC) are covered in Chapter 5, and applications of HPC are described in Chapter 6. To give an indication of the trend of development, several current research programs on HPC are briefly summarized in Chapter 7. Finally, conclusions from this review of the state-of-the-art on HPC are drawn in Chpater 8.

1.5  References

1. P.-C. Aitcin and A. Neville. 1993. High-Performance Concrete Demystified. Concrete International, Jan, Vol. 15, No. 1, pp. 21-26.
2. S. W. Forster. 1994. High-Performance Concrete — Stretching the Paradigm. Concrete International, Oct, Vol. 16, No. 10, pp. 33-34.
3. C. H. Goodspeed, S. Vanikar, and R. A. Cook. 1996. High-Performance Concrete Defined for Highway Structures. Concrete International, Feb, Vol. 18, No. 2, pp. 62-67.
4. M. L. Leming, S. H. Ahmad, P. Zia, J. J. Schemmel, R. P. Elliott, and A. E. Naaman. 1990. High-Performance Concretes: An Annotated Bibliography 1974-1989. SHRP-C/WP-90-001, Strategic Highway Research Program, National Research Council, Washington, D.C., v, 403 pp.
5. P. Zia, M. L. Leming, and S. H. Ahmad. 1991. High-Performance Concretes: A State-of-the-Art Report. SHRP-C/FR-91-103, Strategic Highway Research Program, National Research Council, Washington, D.C., xiii, 236 pp.
6. P. Zia, M. L. Leming, S. H. Ahmad, J. J. Schemmel, R. P. Elliott, and A. E. Naaman. 1993. Mechanical Behavior of High-Performance Concretes, Volume 1: Summary Report. SHRP-C-361, Strategic Highway Research Program, National Research Council, Washington, D.C., xi, 98 pp.
7. P. Zia, S. H. Ahmad, and M. L. Leming. 1996. High-Performance Concretes: An Annotated Bibliography (1989-1994). Federal Highway Administration, McLean, VA., Jun, Publication No. FHWA-RD-96-112, iv, 337 pp.

Table 1.  Definition of HPC according to SHRP C-205 (Zia, et al. 1993)1

Table 1.2 Definition of HPC according to Federal Highway Administration (Goodspeed, et al. 1996)