Date of Graduation


Document Type


Degree Name

Master of Science in Civil Engineering (MSCE)

Degree Level



Civil Engineering


Andrew Braham

Committee Member

Kevin Hall

Second Committee Member

Cameron Murray


asphalt emulsion, Coulter counter, electrical sensing zone, emulsified asphalt, particle size, particle size analysis


As asphalt pavements develop distresses, pavement preservation, maintenance, and rehabilitation treatments are used to mitigate distresses and extend the life of the pavement. Many of these treatments utilize asphalt emulsion. Previous research has linked particle size to material properties including viscosity and storage stability. General statements have also been made about particle size influencing emulsion performance while other researchers have identified a trend between particle size and prime coat penetration. Even though literature discusses the importance of particle size, there is little guidance on the best practices of asphalt emulsion particle size analyses, specifically with a Coulter counter.

Data collected from eight emulsions was analyzed, and a recommended procedure for testing and analyzing particle size results using a Coulter counter was produced in the form of a draft ASTM specification. RStudio was used to identify correlations between particle size parameters and the additional tests.

It is recommended to create three samples for each emulsion being tested and to test each sample three times. Each test should count at least 5,000 particles and a cumulative particle volume of at least 70,000 μm3. To provide values representative of the emulsion, the runs should be averaged together to represent the samples, and the samples should be averaged together to represent the emulsion. The ensure the runs are representative of the samples, the coefficient of variation of the mean particle size in the number basis should be less than 5%. The same is recommended for combining samples to represent the emulsion.

Particle size graphs should be shown as volume % versus particle size and utilize a smoothing technique by averaging up to 7 data points together to create a less cluttered graph. Finally, the analysis using RStudio identified moderate correlations between the viscosity test and the mean, d10, d50, d90, span and standard deviation of -0.548, -0.565, -0.543, -0.574, 0.427, and -0.474 respectively. These correlations along with guidelines from a particle size analyzer manufacturer led to the recommendation of reporting the mean, d50, and span, in the volume basis, as final results to describe a particle size distribution.

These recommendations and guidelines serve as a steppingstone to further research about the best practices of conducting particle size analyses on asphalt emulsions. The results should be validated and refined with a formal experimental matrix.