Author(s):
E. Hargett, B.M. Gallaway, W.W. Scott
Publication Date
October 1969
Abstract
Included in this report are the descriptions and findings resulting from laboratory and field investigations of the use of four manufactured aggregates for the production of asphaltic concrete. The information consists of basic design data for the inclusion of synthetic aggregates in asphaltic concrete mixes, the results obtained from a comprehensive program of laboratory testing of the synthetic aggregates and asphaltic concrete mixes containing the synthetic aggregates. Descriptions of field performance characteristics of asphaltic concrete mixes containing synthetic aggregates are also included.|The laboratory test data were obtained from standard or well established test procedures designed for the evaluation of the physical and engineering properties of the aggregates and asphaltic concrete mixes. The test data relating to the physical properties of synthetic aggregates reflect gradation, specific gravity, unit weight, abrasion, freeze-thaw and absorption of water, of the four synthetic aggregates included in the study. The laboratory test data relating to rational mix combinations reflect asphalt absorption by the aggregate, surface area, asphalt film thickness, air permeability, unconfined compressive strength, swell characteristic, Hveem stability, cohesiometer values, degradation of aggregates during compaction and surface abrasion.|The information relating to field tests reflects test methodology and short term evaluations of the field performance of asphaltic concrete mixes containing manufactured aggregates for both hot-mix hot-laid and hot-mix cold-laid designs. Brief descriptions of previous field tests conducted by the Texas Highway Department also are included to establish the field performance characteristics of this new type of aggregate for the construction of bituminous pavements. The tests that were conducted consist of small scale field tests of cold mixes and a large scale test of the use of the lightweight aggregates for the production of open graded plant mixed seal coats. Open graded mixes as used in this report refer to field void contents in the range of 12 to 24 percent.|The findings reported herein furnish the highway construction industry with basic design criteria for the inclusion of synthetic aggregates in asphaltic concrete mixes as well as laboratory and field test data supporting favorable performance of this new aggregate used as a substitute for natural aggregates. This report also points up a very meaningful characteristic of lightweight synthetic aggregates, namely, the friction textured characteristics are superior to natural aggregates. Extensive field data present ample proof that lightweight aggregate used as the coarse aggregate fraction in bituminous mixes provides long lasting high skid resistance.
Report Number:
110-1F
Link(s):
Document/Product
http://tti.tamu.edu/documents/110-1F.pdf
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