Two popular ground improvement techniques cement grouting and jet grouting both inject a cementitious grout below ground to bind soil.
When it comes to groundwater control and soil stabilization, jet grouting is an innovative technique that is gaining popularity over traditional cement grouting.
There are two main types of jet grouting: single fluid and double fluid. Single fluid jet grouting uses only a cementitious grout injected at high velocities to erode and mix with the soil. The grout hardens to form stable columns that improve ground conditions.
Double fluid jet grouting involves air or water being injected first to loosen the soil, followed by the grout. The two-step process allows for better soil mixing.
Difference Between Jet Grouting and Cement Grouting
While both techniques use cementitious grout, jet grouting vs cement grouting differ significantly in methodology and appropriate applications:
- Jet grouting actively mixes soil while cement grouting passively permeates voids
- Jet grouting has higher equipment requirements and costs
- Cement grouting works best in permeable soils, while jet grouting can improve even low permeability soils
- Jet grouting provides greater depth and larger treated diameter capability
The key differences cover working principles, equipment requirements, soil compatibilities, cost factors, and considerations like noise and environmental impact.
The table summarizes how cement grouting and jet grouting represent varied approaches to improving ground conditions.
| Parameter | Cement Grouting | Jet Grouting |
|---|---|---|
| Working Principle | Permeation of grout into voids in soil | Mechanical mixing of high-pressure grout and soil |
| Equipment Used | Pumps, standard hoses | High pressure pumps, specialized nozzles |
| Pressure Rating | Up to 300 psi | 2000 psi to 6000 psi |
| Soil Types Suited | Permeable soils like sands | Wide variety from soft clays to dense tills |
| Depth of Treatment | Shallow, up to 30 feet | Over 100 feet possible |
| Cost per Linear Meter | Around $50/meter | $100 -$250/meter |
| Quality Control | Simple flow monitoring | Extensive testing of cores |
| Noise and Vibrations | Minimal | Can require sound barriers |
| Treatment Time | Can treat large areas quickly | Discrete columns take more setup |
| Environmental Impact | Grout bleed can contaminate soil | Contained process with spoil removal |
Purpose of Cement Grouting and Jet Grouting
The main purposes of cement grouting and jet grouting include:
- Liquefaction mitigation
- Settlement reduction
- Excavation wall stability
- Slope stabilization
- Underpinning support
- Groundwater control
However, jet grouting can improve problematic soils at greater depths and widths compared to conventional cement grouting. The high pressures finely pulverize soils into a homogeneous mix.
Is Jet Grouting Better Than Cement Grouting?
Jet grouting is not universally “better” than cement grouting. As with most construction methods, the site conditions dictate the preferable technique. Jet grouting clearly offers strengths when:
- Treating dense or poorly permeable soils
- Achieving deep treatment depths is necessary
- Large diameter soil-cement columns are specified
jet grouting involves specialty subcontractors and equipment that increase costs.
However, cement grouting remains a viable alternative for shallow, large-area permeation needs. Appropriate site conditions favor cost-savings from cement grouting strength improvements.
Jet Grouting vs Cement Grouting Cost
Jet grouting costs range from $100 – $250 per linear meter depending on column diameter and local rates.
Cement grouting costs about $50+ per linear meter but is better suited for spreading treatment across wider areas rather than discrete columns. Jet grouting’s higher costs derive from specialty equipment like packers and rigorous quality control testing.
Jet Grouting vs Cement Grouting Equipment
Jet grouting equipment employs flow rates over 100 gpm delivered at pressures ranging from 2,000 – 6,000 psi. Hoses contain high-strength synthetic fibers and kink protection layers to endure the demanding conditions.
Cement grouting equipment has maximum pressures around 300 psi with lower flow rates less than 20 gpm. Standard hoses suffice given the less stringent fluid parameters.
Advantages of Jet Grouting over Cement Grouting
Jet grouting advantages include soil mixing ability, controlled column sizes, rapid installation, and treatment near buried structures.
Cement grouting enables large area permeation, lower costs, and simpler equipment logistics.
Key advantages of jet grouting over cement grouting include:
- Treatment of all soil types
- Controlled column diameters up to 6 feet
- No spoil removal needed
- Rapid installation rates
- Less surface settlements
- Treatment adjacent to buried structures
Disadvantages of Jet Grouting and Cement Grouting
Jet grouting has higher costs and complexity than cement grouting. Cement grouting cannot uniformly improve poorly permeable or coarser soils.
Disadvantages of jet grouting over cement grouting includes–
- High equipment costs
- Requires specialty contractors
- Quality control testing is extensive
- Noise pollution regulates operations
When to Use Jet Grouting Instead of Cement Grouting
Jet grouting applications well-suited over cement grouting involve:
- Sites with boulders/cobbles
- Areas inaccessible to drilling equipment
- Deep mixing requirements
- Large diameter column needs
- Soil densification under foundations
Jet Grouting vs Cement Grouting-for Ground Improvement
While both methods provide ground improvement, jet grouting enables superior, consistent soil modification regardless of native conditions, while cement grouting remains the more economical choice for gently improving large areas of permeable near-surface deposits.
Jet grouting can achieve higher densification, shear strength and bearing capacities in coarser-grained soils like sands and gravels. The increased mixing energy uniformly improves the entire column.
With cement grouting, properties vary between the improved zones near bleed channels versus less permeated areas.
Single Fluid Jet Grouting vs Double Fluid Jet Grouting
Single fluid jet grouting uses just grout for simpler setups, while double fluid jet grouting adds air or water for enhanced soil erosion effects and larger column sizes.
Double fluid jet grouting also substantially increases production rates if the soil conditions permit.
Conclusion
Jet grouting and cement grouting each have inherent advantages and limitations for ground improvement.
Jet grouting requires greater expertise and costs, but can stabilize even difficult soil conditions using metered columns.
Meanwhile, cement grouting affordably permeates permeable soils across larger areas where deep rigor is unnecessary.
