Document Type

Thesis - Open Access

Award Date

1972

Degree Name

Master of Science (MS)

Department

Civil Engineering

Abstract

Both the producer and the user are concerned with a characteristic of an aggregate that may be best described as "durability." In a broad sense, durability means the ability of the aggregate to remain unchanged over a fairly long period of time in spite of adverse natural processes or forces to which it is subjected. Durability, as it applies to mineral aggregates, means the ability to resist degradation. Erickson has defined degradation as "A breaking down and/or disintegration of particles of sand, gravel, or stone, primarily due to alteration and subsequent decomposition of their mineral components, accelerated by the action of mixers, mechanical equipment, traffic or the elements." Mechanical degradation is the result of stockpiling, placing, and compacting the aggregate during construction. Such traffic conditions as impact and abrasion may also cause mechanical degradation. Pauls and Carpenter observed that the principal cause of aggregate degradation results from compaction or the rolling operation during construction. Shelburn found as a result of his research that a bituminous coating gives only slight protection against degradation of the aggregates. McNaughton discovered that under traffic loads aggregate shift about and rearrange themselves so that they occupy the least possible space. Because of this particle movement, a grinding effect occurs which tends to wear angular aggregate smooth. This wearing of the aggregate produces fines which fill the voids of the structure. Usually there is an increase in strength of the structure as the amount of fines produced increases; however, there is a loss in structural strength if more fines are produced than are needed to fill the voids.

Library of Congress Subject Headings

Aggregates (Building materials)
Road materials

Format

application/pdf

Number of Pages

67

Publisher

South Dakota State University

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