Theses and Dissertations

ORCID

https://orcid.org/0000-0001-6708-6839

Issuing Body

Mississippi State University

Advisor

Howard, Isaac L.

Committee Member

Cox, Benjamin C.

Committee Member

Knizley, Alta

Committee Member

French, William T.

Date of Degree

12-13-2024

Original embargo terms

Worldwide

Document Type

Dissertation - Open Access

Major

Civil Engineering

Degree Name

Doctor of Philosophy (Ph.D.)

College

James Worth Bagley College of Engineering

Department

Richard A. Rula School of Civil and Environmental Engineering

Abstract

Volumetric properties have been the cornerstone of asphalt mixture design and control dating back to the early 20th century. However, social and economic drivers have caused the asphalt industry to make changes in materials and processes used to produce mixtures that have stretched the limits of volumetric centric methodologies. The primary objectives of this dissertation were to present an extensive case on how volumetrics is limited in their ability to characterize asphalt mixtures and to advance the body of knowledge of a viable alternative. State agency specifications were examined and found that Departments of Transportation (DOTs) were using asphalt volumetric properties inconsistently across the southeast U.S. A series of data driven computations were conducted to determine if correlations existed between volumetric properties and measured mixture properties utilizing a statewide asphalt mixture design database and a multiyear compilation of quality control data for a single mixture. The second focus employed Cantabro Mass Loss (CML) testing in a multifaceted study to index CML against other mechanical property tests, conduct and assess CML alongside daily volumetric testing, improve CML laboratory conditioning procedures, and begin establishing CML single and multilaboratory variability standards. Data analysis was unable to determine any strong relationships between volumetrics and any other measured properties, which strengthens the case against sole reliance on volumetrics for asphalt mixture characterization. CML was shown to potentially be a more robust test compared to the other mechanical property tests because of its ability to react in an expected manner to field aging and increasing air voids. A modest trend was established between CML, and other mixture properties indicated that changes in volumetric properties individually do not raise concern but in combination they could negatively impact quality. Time-optimized conditioning protocols resulted in favorable field aging simulated years based on the available data, but more testing is recommended for some situations. Round robin testing was able to establish acceptable differences for a single test containing three replicates, however a useable allowable difference between two laboratories was not determined, and a second study is recommended using the single test differences to improve accuracy.

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