Sustainability in Practice: A Brief History of Innovation in Deep Soil Mixing

Soil mixing has been successfully used around the world for both temporary and permanent applications in some of the most challenging geologic conditions and, as a design-build system, remains a cost-effective alternative to traditional deep foundations and structural earth retention systems. With continued growth of soil mixing markets, practitioners have constantly reduced scope through better designs, increased production using more efficient equipment and methods, lowered material consumption with improved quality control, and utilized less carbon intensive materials when available. The construction industry has traditionally measured the success of these innovative ideas using scheduling and financial metrics, which have been the principal marketing tools in the expansion of soil mixing as an efficient and robust geotechnical solution. However, our industries rarely acknowledge that the implementation and accumulation of these innovative ideas over the past decades has also significantly reduced the environmental impact of our soil mixing work. As sustainability metrics become more prominent in civil construction, practitioners should look back at the design and operational innovations that have reduced both embodied carbon and project costs in soil mixing solutions to exemplify how we continue to make soil mixing a sustainable geotechnical solution. This paper reviews several of the innovative ideas already implemented in soil mixing that have allowed practitioners to reduce scope, improve production, and produce better quality; all of which have resulted in the continued acceptance of soil mixing solutions while reducing both project costs and environmental impact. The objective is to illustrate the evolution and compilation of our good ideas, lessons learned, and innovative processes into making soil mixing safer, more efficient, and cheaper; and provide some insight into the future of sustainability initiatives in deep mixing.