Document Type

Thesis - Open Access

Award Date

1968

Degree Name

Master of Science (MS)

Department

Civil Engineering

Abstract

The amount of highway construction is increasing every year. As a result, there is an ever increasing demand for mineral aggregates. Engineers classify these mineral aggregates as the smaller rocks which are composed of one or more minerals. In the state of California, between one-fifth and one-third of the 300 million dollars spent annually for the construction of highways is used for the procurement and placement of aggregates. (l) This cost is steadily increasing because of the depletion of the more accessible and higher quality aggregates. Because the traffic volume and loads are steadily increasing, the Interstate system as well as many other primary roads being built demand durable aggregates. The selecting of high quality aggregates is not a new problem. Back in Roman times it was necessary to select suitable rocks for use as flag stones, a surfacing material of the time. Some of the highways of that era remain in excellent condition today as a result of the prudent selection of surfacing material. It was not until the late nineteenth century, however, that the use of machines to simulate field conditions for the purpose of determining the durability of aggregates began. The first successful test for abrasion of aggregates was the Deval test. At the present time the Los Angeles rattler tests used by most of the State Highway Departments. It is considered the most effective test for determining the structural and abrasive qualities of an aggregate. In the late 1940's however, it was observed that aggregates which had passed the Los Angeles rattler test were failing under field conditions. In 1947, Melville investigated a failure in Route 250 near Charlottesville, Virginia. From his investigation he concluded that the aggregates had weathered sufficiently to produce a layer of plastic fines which caused the failure. (2) Since then there have been many similar cases reported, especially in the western states. As a consequence of· these failures, many of the western states have been attempting to develop an empirical test that will determine the tendency of an aggregate to produce plastic fines. Washington, Oregon, Idaho, California, and South Dakota, as well as other states, have developed tests to determine the durability characteristics of aggregates. At the present time, none of these tests are universally accepted by other states or by the American Society for Testing and Materials. The Los Angeles rattler test is a very simple test and requires little time to perform. The amount of time required to conduct a test is becoming increasingly important because labor costs are steadily rising. Also, with the high production of modern aggregate contractors, it is important to have a test which can be accomplished in a short period of time. The Los Angeles rattler machine is an expensive piece of equipment and one that all state highway departments regard as standard equipment. Accordingly, this study was made with a view toward modifying the Los Angeles rattler test to include wet abrasion. This would make it possible to obtain the necessary durability information from a single laboratory test without appreciably adding to the cost of equipment.

Library of Congress Subject Headings

Road materials -- Testing

Format

application/pdf

Publisher

South Dakota State University

Share

COinS