Laboratory study of larger sized aggregate in Portland cement concrete

Abstract

A laboratory examination of the effects of coarse aggregate type and size on the mechanical properties of concrete is presented, in an effort to develop more cost-efficient mixes for pavements and other highway structures. Aggregate blending is used to generate the required coarse aggregate gradations. Six different concrete mixes are prepared, using three different coarse aggregate gradations, along with two different aggregate types, natural and crushed. Test results show that coarse aggregate properties often do not have a significant effect on the mechanical properties of concrete. When significant differences are observed, these are confounded by variability issues related to the testing protocols themselves, and by mineralogical distinctions among the various aggregate blends.

Keywords:

• Coarse aggregate
• Portland cement concrete mix design
• Pavements
• Mechanical properties

Acknowledgements

This investigation was sponsored by the Ohio Department of Transportation (ODOT) and by the Federal Highway Administration (FHWA) as Ohio State Job No.: 14803(0); Contract No.: 11494, under project “Larger sized coarse aggregates in Portland cement concrete pavements and structures.” The principal investigators were Drs Anastasios M. Ioannides and Richard A. Miller, Department of Civil and Environmental Engineering, University of Cincinnati. The ODOT Technical Monitor was Mr Bryan Struble; the Administrator for the Office of Research and Development at ODOT was Ms Monique Evans; and the FHWA liaison in Columbus, OH was Mr Herman Rodrigo. The assistance, cooperation and friendship of these individuals were major contributors to the success of the study, and their support is gratefully acknowledged. Special thanks are also extended to Messrs Lloyd Welker and Tim Jones of ODOT. The sand and both kinds of coarse aggregates were supplied free of charge by Martin Marietta Materials, through Mr Jim Martin. The cement was donated by CEMEX, through Mr Steve Reibold. The admixture was contributed at no cost by Master Builders, Inc., through Mr Greg Wirthlin. The authors also acknowledge the contributions to the project of graduate students Kristy M. Walsh and Amarendranath Deshini.