When considering Low Impact Development (LID) applications, certain types of pavers are not suitable due to their limitations in strength, durability, and permeability. Rolled plastic pavers, rigid plastic pavers, and some lightweight permeable pavers often fall short in meeting the requirements for effective stormwater management and load-bearing capacity in LID projects. This article explores the specific types of pavers that are not recommended for LID applications and the reasons behind their unsuitability.
What Are the Main Types of Pavers Unsuitable for LID?
The primary types of pavers that are generally not suitable for LID applications include:
- Rolled plastic pavers
- Rigid plastic pavers
- Certain lightweight permeable pavers
These pavers often lack the necessary structural integrity, load-bearing capacity, and long-term durability required for effective LID implementations.
Why Are Rolled Plastic Pavers Unsuitable for LID?
Rolled plastic pavers present several challenges that make them unsuitable for LID applications:
- Low Strength: Their thin cell walls and lack of flex joints make them prone to buckling under pressure.
- Installation Difficulties: They require frequent staking, increasing installation time and cost.
- Permeability Issues: The fabric attached to the bottom can clog quickly, reducing water infiltration.
- Structural Weakness: Low torsional strength leads to breakage under vehicle turns.
What Limitations Do Rigid Plastic Pavers Have in LID Projects?
Rigid plastic pavers, while usable in some light-duty applications, have significant limitations for LID projects:
- Inflexibility: They don’t adapt well to ground variations or slopes, leading to potential cracking.
- Low Torsional Strength: Susceptible to breaking or popping up when vehicles turn.
- Aesthetic Concerns: Temperature changes can cause cracking, affecting appearance and durability.
How Do Permeable Pavers Fall Short in LID Applications?
While permeable pavers are often used in LID, certain types and situations make them unsuitable:
- Load Capacity Limitations:
- Lightweight permeable pavers may not withstand heavy vehicle traffic.
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Additional structural components like geogrids may be necessary for high-load areas.
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Clogging Issues:
- Over time, permeable pavers can clog, especially if not properly maintained.
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Exposure to sediment or road sand can significantly reduce permeability.
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Site Constraints:
- Not recommended for slopes greater than 5%.
- Unsuitable for areas with high groundwater tables without additional measures.
What Are the Specific Measurements and Weight Capacities to Consider?
When evaluating pavers for LID applications, consider these specifications:
| Paver Type | Typical Thickness | Load-Bearing Capacity |
|---|---|---|
| Pervious Concrete | 100-150 mm | Varies based on mix design |
| Porous Asphalt | 50-100 mm | Depends on base structure |
| Plastic Pavers (e.g., TRUEGRID) | Varies | Up to 8,000 psi compressive strength |
- Base and subbase layers must be designed for appropriate load-bearing capacity.
- Granular subbase with clear, crushed stone is often required.
What Challenges Are Associated with Lightweight Pavers in LID?
Lightweight pavers present several challenges in LID applications:
- Structural Integrity: Lack the strength to handle significant loads or traffic.
- Aesthetic Issues: Prone to cracking and non-uniform appearance over time.
- Installation and Cost: Often require specific techniques and materials, increasing overall cost.
How Do Cost and Installation Factors Affect Paver Suitability?
Cost and installation considerations play a crucial role in determining paver suitability for LID:
- Cost Comparison:
- Permeable paving solutions can be more expensive than standard asphalt.
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Some options, like Ecoraster, are cost-competitive with interlocking paving stones and concrete.
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Installation Requirements:
- Best practices include using clean, angular permeable paving stones for the base.
- Proper surface preparation is crucial for longevity and effectiveness.
- Some systems, like Ecoraster, offer pre-assembled grid layers for faster installation.
In conclusion, when selecting pavers for LID applications, it’s crucial to avoid rolled plastic pavers, rigid plastic pavers, and certain lightweight permeable pavers due to their limitations in strength, durability, and permeability. Proper consideration of load-bearing requirements, site conditions, and long-term maintenance needs is essential for successful LID implementations.