In the United States, the primary use of high-strength concretes has been in columns of high-rise buildings. However, in recent years high-strength concrete has been used in applications where durability is important. This has resulted in research into material and structural properties other than compressive strength. This paper summarizes selected research projects in the United States. In materials research, projects have been conducted to identify the relationship between water-cementitious ratio and compressive strength, the development of compressive strength with time, and the effects of heat of hydration on in-place material properties. Research has also been conducted to assess the testing procedures to be used with high-strength concrete. Specific projects include work on the use of smaller test specimens and different capping materials. In structural research, projects have been conducted to identify how the structural performance of high-strength concrete members differs from that of conventional strength concrete members. Specific research projects have involved investigations of modulus of elasticity, creep, shrinkage, development length, shear strength, and column strength. Although research is underway on a number of topics, additional work is still needed to answer questions about the applicability of code provisions for high-strength concrete. A list of specific topics is included in the paper.

A consortium of six companies and two governmental research funding organizations are carrying out a six-year research and development program on high performance concrete in Sweden. In mid-94, half the program time was completed. The program focused on research directed towards the understanding of mechanisms and subsequent modeling and experimental verification. It also included application and oriented research aiming at the establishment of technical relationships. This should further lead to practical recommendations and guidance for use in specific projects or product and process development within the industry. The program was divided into 17 different subprojects that were grouped under the headings of materials, production technique, and structures. The fields of research were selected following an evaluation of the possibilities offered by dense, low w/c ratio cementitious systems in improving performance, but at the same time the potential risks when using these systems were addressed. An evaluation on possible application areas resulted in the study of certain aspects of structural behavior. The research was carried out at eight different research entities in Sweden as well as by research and development personnel from the consortium participants. The work was done in laboratories as well as in situ.

This paper reviews the developments of HPC in France for the past ten years in bridges, buildings, tunnels, offshore platforms, and nuclear containers. Different projects are presented wherein 55 to 80 MPa concretes were used. The motivation for using HPC are many. The future developments initiated by owners, public research institutes, consultants, and contractors are documented and innovative materials are introduced, as well as research program initiated by different laboratories.

Sixteen agencies of the United States Federal Government have developed an interagency proposal for promoting the use of high performance concrete and other materials for use in the Nation's Infrastructure. They are working jointly with the Civil Engineering Research Foundation (CERF) to enlist private sector support for sponsoring a research and development program aimed at getting the materials into use. CERF is drawing upon the technical community such as that in ACI to define the various research needs and studies which will lead to materials acceptance. Materials other than concrete are addressed in other parts of the total program. Workshops were held in the spring and fall of 1993 to develop schedules and priories. A tentative cost for the concrete program is approximately $200 million over 10 years, which includes some technology transfer and which would be expected to be matched by some private sector funding.

Ferrocement is a type of thin-wall reinforced concrete with high performance characteristics such as high tensile strength to weight ratio, ductility, and impact resistance. Basic considerations of the materials used, fine galvanized wire mesh and a cement mortar coupled with its good crack controlling characteristics, indicated that ferrocement will provide better durability, ease of maintenance, and lower life cycle cost. It can be cost competitive through mechanized production and proper choice of reinforcement. The National University of Singapore has since the early 1970's made considerable efforts in popularizing ferrocement through research and development. Several studies have been conducted on the application and performance of prototype ferrocement structural elements. Some of the applications such as sunscreens, secondary roofing slabs, and water tanks for high-rise buildings are presented in this paper.