Evaluation of Texas DOT Item 334, Hot-Mix, Cold-Laid Asphalt Concrete Paving Mixtures

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Author(s):

C.K. Estakhri, L. Jiminez, J.W. Button

Publication Date:

April 2000

Abstract:

Texas Department of Transportation (TxDOT) maintenance personnel have noted problems with a commonly used, stockpiled maintenance mix known as Item 334, Hot-Mix Cold-Laid Asphalt Concrete Paving Mixture (HMCL). It is generally used by maintenance personnel as a blade-on/level-up material and as a pothole repair material. Performance problems include stripping in the stockpile, a tendency towards instability in hot weather, and a lack of winter workability.|The objective of this research project was to identify a series of simple but meaningful laboratory tests and acceptance criteria for HMCL patching materials that will ensure reasonable stockpile life and field performance. A literature review was conducted to identify published information on patching materials with a particular emphasis on test procedures that have been developed for maintenance mixtures. A survey was performed of maintenance personnel in all of the TxDOT district offices to identify problems.|Several different HMCL mixtures were designed and evaluated in the laboratory. These mixtures were designed using two types of aggregates (crushed gravel and crushed limestone) and three types of binders (AES-300S, MC-800, and MC-800 with diesel) for a total of six different mixtures. Laboratory tests indicated that mixtures designed at 92 percent density had Marshall stabilities and unconfined compressive strengths as high or higher than those designed at 95 percent density.|Field mixtures were evaluated in the laboratory as a function of stockpile age. Several simple test procedures were evaluated such as the rolling sieve cohesion test and various workability test procedures.

Report Number:

1717-1

Keywords:

Asphalt Paving Mixtures, Maintenance Mixtures, Patching Materials, Premix, Cohesion, Workability

Electronic Link(s):

Document/Product: http://tti.tamu.edu/documents/1717-1.pdf

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