In modern construction projects, ground improvement through grouting is commonly used to ensure structural stability and safety. This technique, which involves injecting stabilizing materials into the soil, is essential for buildings in earthquake-prone regions and areas with adverse ground conditions. From securing foundations and preventing soil erosion to strengthening underground structures, grouting plays a vital role in creating a resilient infrastructure capable of withstanding environmental stresses and geological challenges.
However, traditional grouting methods have long posed significant environmental challenges. The construction industry's heavy reliance on silica-based chemical grouts, produced through energy-intensive processes, contributes substantially to global carbon dioxide (CO2) emissions. With growing pressure to reduce its environmental impact, developing sustainable alternatives to conventional grouting materials has become a critical priority for scientists and engineers worldwide.
Against this backdrop, a research team from the Shibaura Institute of Technology, Japan, has developed an innovative solution that could revolutionize ground improvement through grouting. Led by Professor Shinya Inazumi of the College of Engineering, the research team developed a novel carbon-neutral grout called Colloidal Silica Recovered from Geothermal Fluids (CSRGF), that enhances soil stabilization while simultaneously reducing the environmental impact of construction and geothermal energy harvesting. Their study was made available online on January 22, 2025, and will be published in Volume 22 of Case Studies in Construction Materials in July 2025.
"Geothermal energy production generates large amounts of silica-rich waste fluids, which traditionally pose maintenance and disposal challenges," explains Inazumi, "By repurposing this waste into a high-performance CSRGF grout, we aimed to establish a circular economy approach, transforming an industrial byproduct into a valuable construction material." In doing so, the newly developed grout addresses two major issues—preventing high-silica-content waste fluids from damaging geothermal energy harvesting equipment and minimizing the carbon footprint of conventional grout production.
Extensive laboratory tests demonstrated the grout's remarkable performance, showing a 50% increase in liquefaction resistance compared to existing materials. Its low viscosity and controlled gelling time allow deep soil penetration while meeting environmental safety standards. These properties make CSRGF grout particularly valuable in earthquake-prone regions, where soil stabilization is crucial for preventing structural damage during seismic events.
Notably, the applications for CSRGF grout extend beyond earthquake protection. Its superior water-sealing properties make it ideal for underground construction projects, including tunnels, subways, and basements, where water infiltration threatens structural integrity. Additionally, in coastal and flood-prone areas, CSRGF grout can reinforce soil to combat erosion and mitigate risks associated with rising sea levels.
The development of CSRGF grout marks a significant milestone in the construction industry's journey toward carbon neutrality. By repurposing industrial byproducts and reducing waste, this innovation demonstrates how circular economy principles can drive more sustainable construction practices. Moreover, its cost-effective and scalable production reduces CO2 emissions in construction. Its adoption aligns with international sustainability initiatives, setting new industry standards for environmentally responsible soil stabilization. "By replacing traditional silica-based grouts with our sustainable alternative, the construction industry can advance toward a greener infrastructure development, supporting global efforts to achieve carbon neutrality by 2050," says Inazumi.
The research team's next steps include scaling up production and conducting field trials to further validate the material's performance under real-world conditions. As the construction sector strives to balance sustainability with high performance, this innovation showcases the power of innovative thinking in solving engineering challenges sustainably.
