ISSN: 1945-7553
CODEN: JTEVAB
Published Online: 1 March 2012
Page Count: 18

Comparison of Shape Parameters for Selected Coarse Aggregates in Oklahoma

Singh, Dharamveer
Research Associate, School of Civil Engineering and Environmental Science, the Univ. of Oklahoma, Norman, OK

Zaman, Musharraf
Associate Dean for Research and Graduate Programs, College of Engineering, the Univ. of Oklahoma, Norman, OK

Commuri, Sesh
Professor, School of Electrical and Computer Engineering, the Univ. of Oklahoma, Norman, OK

(Received 19 October 2011; accepted 9 February 2012)

Abstract

The performance of pavement can be significantly influenced by the gradation and shape parameters of the aggregates (i.e., angularity, texture, form, and sphericity). An accurate measurement of these properties is important for the development of specifications for the quality control and quality assurance of aggregates. The present study was undertaken in order to compare the shape parameters of different types and sizes of selected coarse aggregates that are commonly used in Oklahoma. Three different types of aggregates—granite, rhyolite, and limestone—were collected from stockpiles. Each type of aggregate was divided into three different sizes of coarse aggregates. These sizes include the following: passing through a 19 mm sieve and retained on a 12.5 mm sieve (CA1), passing through a 12.5 mm sieve and retained on a 9.5 mm sieve (CA2), and passing through a 9.5 mm sieve and retained on a 4.75 mm sieve (CA3). CA1 type aggregates had the largest size, followed by CA2 and CA3. An automated aggregate imaging measurement system was used to measure the shape parameters of the aggregates. The results show that the aggregates become smooth (low texture) and elongated (high form and low sphericity) as their size decreases. No relation was observed between the particle size and the angularity of the aggregates. A comparison of different types of aggregates indicated that, in general, granite aggregates were highly rough (high texture) and cubical (low form and high sphericity) compared to rhyolite and limestone aggregates. Similarly, the angularity of granite aggregates was found to be significantly different than that of rhyolite and limestone aggregates. The ranking of the aggregates was done based on the composite shape index factor (CI) for angularity, form, texture, and sphericity. The CI considers the combined effect of the gradation and shape parameters of aggregates. In addition, the ranking of aggregates was further verified by estimating the dynamic modulus (

Keywords:
angularity, texture, form, sphericity, aggregate image measurement system

Paper ID: JTE104455
DOI: 10.1520/JTE104455
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