Masters Theses


"This investigation concerns itself with the problem of mechanical degradation of a coarse aggregate and specifically as it is used as railroad ballast. Laboratory tests were used to study the aggregate with respect to its plastic deformation characteristics, the amount of degradation, changes in gradation, and the rate of change of degradation as a function of the number of load cycles.

The repeated load triaxial tests were used to study how degradation occurs with respect to aggregate gradation, relative density, and the number of load applications. The Los Angeles abrasion test was also used to determine the degradation of the aggregate. The amount of wear of the material as determined by both the triaxial and abrasion tests were compared.

Results of the repeated load triaxial tests indicated that the parameter most greatly influencing the magnitudes of plastic deformation and triaxial degradation was the degree of compaction. Plastic deformation and triaxial degradation were inversely proportional to relative density and gradation. The majority of the ultimate deformation and degradation occurred during the initial load cycles with reduced amounts for successive cycles. Los Angeles abrasion tests misrepresented field loading conditions during degradation of the crushed limestone"--Abstract, page ii.


Stephenson, Richard Wesley

Committee Member(s)

Heagler, John B., 1924-1999
Rockaway, John D.


Civil, Architectural and Environmental Engineering

Degree Name

M.S. in Civil Engineering


University of Missouri--Rolla

Publication Date

Spring 1980


viii, 77 pages

Note about bibliography

Includes bibliographical references (pages 73-76).


© 1980 Mark Alan Roenfeldt, All rights reserved.

Document Type

Thesis - Restricted Access

File Type




Subject Headings

Aggregates (Building materials) -- Analysis
Deformations (Mechanics)
Strains and stresses
Ballast (Railroads) -- Testing

Thesis Number

T 4583

Print OCLC #


Electronic OCLC #


Link to Catalog Record

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