Congratulations to Antonio Bobet, Edgar B. and Hedwig M. Olson Professor in Civil Engineering, Marika Santagata, Professor of Civil and Construction Engineering, and alumna Kanika Gupta (PhD 2025), recognized with an honorable mention by the American Association of State Highway and Transportation Officials (AASHTO) for high value research conducted with the Indiana Department of Transportation (INDOT) on detection and assessment of sulfates in the pavement subgrade.

The research project addressed a problem encountered by INDOT when rehabilitating or maintaining roads -  the detection of sulfate in existing lime-treated subgrades. Due to concerns with sulfate induced heave, current specifications require removal of the soils when a certain sulfate threshold is exceeded, but no allowance is made for sulfate introduced as part of chemical treatment/modification. The problem is significant, given the number of ongoing or planned maintenance and rehabilitation projects in Indiana, and the wide use that has been made of chemical modification in the state over the past decades.

The project evaluated the performance of the ITM-510 test, a colorimetric test method utilized by INDOT to detect sulfates in soils, through an extensive program of laboratory experiments. The research showed that the ITM-510 test method provides sufficiently accurate measurements of sulfate content in soils, and that impurities present in lime and lime kiln dust used for subgrade treatment are most likely the source of sulfates in existing treated subgrades.

Full details of the project are viewable at https://docs.lib.purdue.edu/jtrp/1882/.