Soil Stabilization Using Precipitated Calcium Carbonate (PCC) Derived from Sugar Beet Waste

The objective of this research is to examine the use of precipitated calcium carbonate (PCC), obtained during the production of sugar from sugar beets, and to stabilize subgrades beneath highway pavements or to stabilize foundations built on loess (windblown silt). The research also aims to permanently capture the carbon from PCC in soil. The experimental process involved the collection of representative loess samples, the addition of variable percentages of PCC, and conducting laboratory experiments on compacted PCC soil mixes to evaluate the effect of PCC on subgrades beneath pavement and foundations beneath buildings. Samples of PCC were obtained from the Amalgamated Sugar Corporation, located 187 km away from Pocatello. In addition, soil was collected from local sources in which saturation collapse and damage have occurred in the past. Unconfined compressive strength tests, which index subgrade bearing failures, were performed on both untreated and PCC-treated soils to evaluate the effect of PCC in stabilizing pavement subgrades and foundations as well as sequestering carbon. The experimental test results revealed a significant average increase of 10% to 28% in the strength of loess samples stabilized with 5% PCC compared to the native soil. The chemical composition and microstructure of PCC were further analyzed through energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) tests. EDX analysis unveiled a carbon content of 9% by weight in PCC, which could contribute to the carbon footprint when it breaks down. Additionally, SEM images displayed an unsymmetrical and sub-rounded microstructure of PCC particles. Based on these findings, the study suggests that utilizing PCC could improve the resistance of loess to saturation collapse and potentially reduce carbon emissions associated with cement or lime production while offering an opportunity to use PCC in soil application.