Research needs relating to performance of aggregates in highway construction

Abstract

The purpose of this project, accomplished as part of NCHRP Project 4-8 of the same title, was to discover and describe possible areas of needed research which if successfully pursued would assist the highway materials engineer in development of procedures for the evaluation of aggregate properties and, in turn, would lead to the more efficient use of our aggregate supplies.

A comprehensive series of statements of research problems was developed and categorized into four general areas of study which are:

(I) Portland Cement Concrete

(II) Bituminous Concrete and Related Materials

(III) Base Course and Shoulder Materials

(IV) General (involving at least two of the first three areas)

The formulation of the research problem statements was based upon information obtained from an extensive literature survey, a Workshop Conference involving 51 “authorities” in various fields of aggregates, and a follow-up interview program.

A total of 52 statements was developed with a total estimated cost of $5,499,500. A priority rating system was also developed and applied to each project. If only the top priority project in each of the four study areas were funded, the cost is estimated to be $670,000.

The relative priority ratings indicate the significance of the problem statements. A solution to the priority one project of Group I, for example, relating to D-line cracking in concrete, would cure a persistent problem which engineers thought was solved.

The major conclusion from this study is that the framework for selective aggregate research has now been developed and program funding is the next matter for concern.