Chapter 4. Recommendations For Needed Research

The objective of task E was to develop specific recommendations for needed research where existing research was not sufficient to allow development of proposed revisions to the AASHTO specifications. During the review of the AASHTO specifications, many areas of needed research were identified. For some areas, the amount of needed research was minimal, while major research projects would be needed for others. Many of the areas requiring a small amount of research of a similar nature were combined into a single, more substantial research project. At the same time, it was recognized that the following NCHRP projects were underway or in the process of development and will address some of the research needs identified in this project:

• Project 18-07, Prestress Losses in Pretensioned High-Strength Concrete Bridge Girders.
• Project 12-56, Application of the LRFD Bridge Design Specifications to High-Strength Structural Concrete: Shear Provisions.
• Project 12-60, Transfer, Development, and Splice Length for Strand/Reinforcement in High-Strength Concrete.
• Project 12-64, Application of the LRFD Bridge Design Specifications to High-Strength Structural Concrete: Flexure and Compression Provisions.

Consequently, none of the research problem statements developed on this project overlap the four NCHRP projects listed above.

The end result of the above-mentioned process was a series of 10 proposed research projects. Six of the projects have a strong emphasis on concrete materials technology, while four relate primarily to structural design.

MATERIALS RESEARCH

The following six research projects have a strong emphasis on concrete materials technology:

1. Performance Requirements for HPC.
2. Use of Wash Water in HPC.
3. Air-Void Requirements and Freeze-Thaw Testing Requirements for Durability of HPC.
4. Penetrability Criteria for HPC.
5. Curing of HPC.
6. Procedures for Measuring Compressive and Flexural Strengths of High-Strength Concrete.

STRUCTURAL RESEARCH

The following four projects relate to structural design requirements:

1. Application of Bridge Design Specifications to High-Strength Concrete Structural Members: Material Properties.
2. Application of Bridge Design Specifications to High-Strength Concrete Structural Members: Shear Provisions Except Prestressed Concrete Beams.
3. Verification of Stress Limits and Resistance Factors for HPC.
4. Confinement of High-Strength Concrete Columns for Seismic and Non-Seismic Regions.

For each of these projects, a research problem statement using the NCHRP format is included in appendix F.