National Concrete Pavement Technology Center

Project description

Due to the sustainability, benefit of Portland-limestone cement (PLC) (also referred to as Type IL cement) by reducing greenhouse gas emissions by 10%, it has been increasingly used to replace Ordinary Portland Cement (OPC) in civil engineering applications. In the US and Canada, PLCs are made with Portland cement and between 5% and 15% fine limestone. This type of cement has been considered to have equivalent performance to Type I Portland cement; therefore, a 1:1 replacement policy has been adopted. The conclusion that performance is equivalent was based on testing of ready-mixed concrete or structural concrete. Cement has also been commonly used to treat subgrade soils and bases. Subgrade soils often contain fine particles, including clay particles that can have different minerals. It is well recognized that chemical reactions between cement and clay particles are different from those between cement and aggregates. Since cement-treated subgrade soils and cement-treated bases (CTB) use a smaller amount of cement than concrete, their properties may be more sensitive to possible property changes of limestone cement. Unfortunately, PLC-treated subgrade soils and bases have not been well evaluated; therefore, it is necessary and important to evaluate the performance of PLC mixed with subgrade soils and base materials. This proposed study will evaluate the properties of PLC-treated subgrade soils and treated bases in Kansas as compared with those treated with Type I OPC using laboratory tests.