Linda Jensen heads Arrowwood Landscape Design in Northern Virginia. Here, she explains interlocking concrete pavement systems.
What is interlock?
It is the inability of a paver to move independently of its neighbors. The locking of the pavers causes loads to be spread over a wider area of pavers than where the load was applied. It’s the key to the strength of the pavement system.
What are the components of an interlocking concrete pavement system?
The components include a base, bedding sand, concrete pavers with sand in their joints, and an edge restraint to contain the pavers at the perimeter.
What is the base made of? What kind should be used?
The base is typically made of compacted, crushed stone that varies in size from one inch (25 mm) down to dust. Base materials used under asphalt street pavements are acceptable for use with interlocking concrete pavements. Some parts of the country use cement-stabilized or concrete bases due to weak or slow draining soils. However, most applications use a crushed stone base that’s compacted.
What is geotextile? What does it do? Is it necessary?
Sometimes called filter fabric, geotextile is made of plastic threads that allow water to pass around them, but not small particles of soil. Geotextile separates and contains the base from the underlying soil sub-grade. It allows the base to shed water, and prevents the soil around it from working its way into the base. Without geotextile, the soil will work its way into the base and weaken it. This is a slow process that happens when the soil is saturated with water or during periods of thawing. Geotextile stops this process and extends the life of the base many years. Geotextile is recommended for use over silt and clay soils. It is not essential in sandy soils.
Can I use fabric designed to prevent weed growth in planting beds instead of geotextile?
No, this material is sometimes not as strong as geotextile and can tear easily. Geotextile is designed and manufactured specifically to improve the performance and durability of your investment in an interlocking concrete pavement project.
Should limestone screenings or stone dust be used under the concrete pavers?
No. Most screenings and stone dust have too many fine particles that slow drainage and rut under repeated loads from tires. Concrete sand is recommended. It’s the same sand mixed into concrete pavers.
Should I seal concrete pavers?
Sealing is not essential in many applications but it offers some benefits, like making spills and stains easier to remove. Liquid sealers are applied after the pavers are installed and cleaned. Paver suppliers can recommend cleaners for concrete pavers. Once applied, the sealers soak into the concrete and into the joints. The sealers in the joints help keep the joint sand in place. Sealers are essential for areas around swimming pools.
Are there disadvantages to sealing?
Since they are a transparent paint-like coating, sealers generally need to be reapplied every three to five years. Use sealers specifically for concrete pavers.
How do I remove stains and fix damaged pavers?
If the stain is on one or two pavers, replacing them with new pavers is the easiest way. Depending on the paver, some can be flipped over rather than replaced. Many suppliers of concrete pavers offer cleaners specially made for removing stains and overall cleaning of the surface.
