Concrete Grinding Residue: Its Effect on Roadside Vegetation and Soil Properties
Concrete grinding residue (CGR) is a slurry waste consisting of water and concrete fines generated from diamond grinding operations that is used to smooth a concrete pavement surface. During this process, CGRs are mostly disposed along the roadside, which can influence soils and plant communities along the roadways. To understand the effects of CGR on soil physical and chemical properties and plant growth, a controlled field site at the Kelly Farm in Iowa was used with CGR application rates of 0, 10, 20, and 40 dry ton/acre to test properties of soils and plants before the application and one month, six months and one year after the CGR application. Two roadsides along Interstate 90 in Minnesota where CGR material was applied in the past were investigated as well. Laboratory and field experiments were conducted to measure plant biomass, bulk density, hydraulic conductivity, infiltration, pH, electrical conductivity (EC), alkalinity, metals, cation exchange capacity (CEC), exchangeable sodium percentage (ESP), and percentage base saturation (PBS) of soil samples collected from the test sites. Statistical analyses were conducted to correlate the CGR additions to the properties of soils and plants. The results of statistical analyses from the Kelly Farm indicated that CGR material did not significantly affect soil physical properties and plant biomass but impacted the chemical properties of soil. Changes in some soil properties such as pH and percent base saturation (PBS) due to CGR did not persist after one year. The results from two Minnesota roadsides indicated that the areas receiving CGR applications in the past did not negatively affect soil quality and plant growth.