Role of Blended Cements and Slag Cement to Improve Sustainability of Geotechnical Projects

Portland cement, blended hydraulic cement, and slag cement are all cementitious materials used in deep soil mixing, subsurface grouting, and slurry walls. Portland cement is the “default” cementitious material used in geotechnical applications due to its known properties and history of good performance. Production of Portland cement results in life cycle impacts. Blended hydraulic cement and slag cement are composed of industrial byproducts. Much of life cycle impact of these industrial byproducts has already been borne by the industries that generated them. Life cycle assessments are a means to quantify life cycle impacts and can be used to compare the relative life cycle impacts of one cementitious material or mix design to another. A material with a lower life cycle impact than another is more sustainable. For example, production of slag cement emits 14% of the amount of greenhouse gas, uses less than 1% of the amount of fresh water and recovers 145 times more renewable material than production of a like amount of Portland cement. Owners, engineers, and contractors can contribute to the sustainability of a geotechnical project by increasing the use blended hydraulic cement and slag cement in geotechnical projects while attaining the project’s performance standards. These contributions may competitively position a proposed geotechnical application or cementitious material mix design as accomplishing a more sustainable project.