Introduction
Jet grouting has become a widely used ground improvement technique in tunneling, foundation engineering, excavation support, and groundwater control. By injecting high-pressure grout into soils and creating soilcrete columns or blocks, it provides strength enhancement and permeability reduction in conditions where other methods may fail. Beyond its technical versatility, jet grouting also offers economic and environmental benefits when compared with alternative ground improvement approaches. This article highlights the cost advantages, sustainability aspects, and resource efficiency of jet grouting in modern geotechnical projects.
1. Economic Benefits
a) Versatility in All Soil Types
- Jet grouting can be applied in clays, silts, sands, gravels, and even mixed ground.
- Eliminates the need for switching to alternative (often costlier) methods when unexpected soil conditions are encountered.
- Reduces project delays and redesign costs.
b) Reduction in Dewatering and Support Costs
- By creating impermeable cutoff walls or bottom plugs, jet grouting reduces or eliminates extensive dewatering systems.
- This saves energy, pumping costs, and time during excavation.
c) Optimized Foundation Design
- Jet grout columns beneath rafts or piles increase soil bearing capacity and reduce settlements.
- Allows for smaller structural elements (thinner rafts, shorter piles), leading to significant material savings.
d) Minimized Construction Disruptions
- Jet grouting equipment is relatively compact and can operate in confined urban areas.
- Minimizes disruptions to traffic, utilities, and adjacent structures—reducing indirect costs.
e) Longevity and Reduced Maintenance
- Soilcrete exhibits long service life (often 30–50 years or more).
- Fewer repairs and remedial measures lower the lifecycle cost of infrastructure.
2. Environmental Benefits
a) Reduction in Excavation and Spoil
- Unlike deep replacement methods, jet grouting treats soils in situ.
- Generates less excavation waste, reducing disposal needs and environmental footprint.
b) Control of Groundwater and Seepage
- Jet grout cutoff walls limit groundwater drawdown compared to large-scale pumping.
- Helps preserve aquifers and reduces settlement of nearby structures due to water table lowering.
c) Lower Carbon Emissions Compared to Alternatives
- Savings in excavation, transport of materials, and reduced dewatering operations contribute to lower greenhouse gas emissions.
- Blended cements and supplementary cementitious materials (e.g., fly ash, slag) further reduce CO₂ footprint.
d) Protection of Surrounding Environment
- Minimizes ground movements, which reduces the risk of damage to historic structures, utilities, and ecosystems.
- Prevents contamination migration by sealing permeable strata.
e) Adaptability to Urban Sustainability Goals
- Jet grouting supports sustainable construction practices in cities where space is limited, minimizing both social and environmental impacts.
3. Comparative Example
| Parameter | Jet Grouting | Alternative (e.g., Diaphragm Wall + Dewatering) |
| Excavation Volume | Minimal | Large |
| Spoil Generation | Moderate (cuttings + grout spoil) | High |
| Water Management | Localized cutoff | Extensive pumping required |
| Urban Applicability | Compact rigs, minimal disturbance | Large equipment, major disruption |
| Cost Efficiency | High for mixed/complex soils | Higher in variable soils |
| Environmental Impact | Lower carbon footprint, aquifer preservation | Higher emissions, groundwater drawdown |
4. Case Insights
- Metro Construction (Europe): Jet grout plugs allowed excavation below groundwater level without long-term pumping, reducing both costs and energy use.
- River Embankment Cutoff (Asia): Jet grouting provided a watertight barrier with minimal soil replacement, protecting groundwater quality.
- Foundation Improvement for High-Rise (Middle East): Soilcrete columns reduced raft thickness, cutting down on concrete use and lowering embodied carbon.
Conclusion
Jet grouting is not only a technically versatile ground improvement method but also provides significant economic and environmental advantages. Its ability to reduce excavation, minimize dewatering, adapt to diverse soils, and extend the service life of infrastructure makes it a cost-effective and sustainable choice for modern geotechnical projects.
As sustainability becomes central to civil engineering, the integration of jet grouting with low-carbon materials, optimized mix designs, and efficient monitoring systems will further enhance its role in eco-friendly construction practices.
