Impact of Equipment Type on Measured Particle Size of Civil Engineering Materials

Abstract Particle size analysis (PSA) captures the size distribution of finely graded materials with particles generally smaller than 1000 microns. Many civil engineering materials do not leverage PSA for material specifications or acceptance despite the insight into material performance and quality gained through understanding the particle size. The objectives of this study are to compare PSA measurement principles by testing 13 civil engineering materials by laser diffraction, Coulter counter, and microscopy. Asphalt emulsions, cementitious materials, sands, clays, and biological samples were selected to represent a wide set of interests and shapes. It was found that between laser diffraction and Coulter counter measurements for materials of the same batch the median (d 50 ) differed by 6% for sand to 37% for cement and the span differed by 26% for clay to 84% for sand. The size of higher sphericity particles was more consistent across measurement principles, highlighting potential measurement biases due to spherical particle idealization prevalent in sizing equipment. Various considerations for PSA testing are highlighted to recognize potential practical concerns for the future development of standard procedures. Standard development should be refined with input from future studies and target a scope of specific materials or material applications.