Landscaping Questions & Answers

Q. Can you assist me in calculating estimated stone needed?
A. YES, we can provide you with the coverage and price of your estimated area. Simply use our project estimator or fill out our quote request form.

Q. What are the components of an interlocking concrete pavement?
A. 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.

Q. What is the base made of? What kind should be used?
A. The base is typically made of compacted, crushed stone that varies in size from one inch (25mm) 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 based due to very weak or slow draining soils. However, most applications use a crushed stone base that’s compacted.

Q. What is geotextile? What does it do? Is it necessary?
A. Sometimes called filter fabric, geotextile is made of plastic threads that allow water to pass around them, but not very small particles of soil beneath them. Geotextile separates and contains the base from the underlying soil subgrade. 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 by many years. Geotextile is recommended for use over silt and clay soils. It is not essential in sandy soils.

Q. Is it okay to use fabric designed to prevent weed growth in planting beds instead of geotextile?
A. NO, this material is sometimes not as strong as geotextile and can tear easily.

Q. Should limestone screenings or stone dust be used under the concrete pavers? What is recommended by the Interlocking Concrete Paver Institute (ICPI)?
A. NO. Most screenings and stone dust have too many fine particles that slow drainage and rut under repeated loads from tires. Sand made with crushed shells (common in Florida) shouldn’t be used either. Concrete sand is recommended. It’s the same sand mixed into concrete pavers and poured, cast-in-place concrete.

Q. What is interlock?
A. In short, it’s the inability of a paver to move independently of its neighbors. It’s the locking of the pavers that 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.

Q. Should I seal concrete pavers?
A. 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 are cleaned. Once applied, the sealers soak into the concrete and into the joints. The sealers in the joints help keep the joint sand in place and prevent weeds and ants, and sealers are essential for areas around swimming pools. Contact us and we can recommend the appropriate sealer or cleaner for your particular application.

Q. Are there disadvantages to sealing?
A. 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. More intense use of the pavers and extreme climates often increase the need for re-applying a coat of sealer.

Q. How do I remove stains and fix damaged pavers?
A. If the stain is 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. For our recommendation on the right cleaner to use for your particular application, contact us.

Q. Is it okay to use stone dust or limestone screenings for bedding sand?
A. NO, these materials are generally not suitable for bedding sand. Screenings are waste material from crushing stone at the quarry. That’s why the price is lower than bedding sand recommended by ICPI. Screenings are the particles that fall off the screens when aggregate is separated into different sizes. Screenings have a lot of fines, i.e. material passing through the No. 200 (0.075mm) sieve.

Yes, screenings and stone dust pack well under a plate compactor, but that’s just the problem. The bedding layer is not a base. It needs to shed water that comes through the joints in the pavement, particularly in the early life of the pavement. The bedding layer must drain, and in order to do that, less than 1% of the material should pass the No. 200 sieve. That means washed sand should be used. The gradation should conform to ASTM C 33, the gradation for sand to make ready-mixed concrete, but cost added to the entire job will be lower than the repairs due to sand not draining. To refer to the recommended bedding sand gradation, see the ICPI Tech Spec #9, a guide specification for the installation of interlocking concrete pavements.

Q. How do I avoid scuffing the surface of concrete pavers during compaction, especially if they are embossed or profiled pavers?
A. Before applying the plate compactor, cover the area (or part of it) with a woven geotextile. This is inexpensive and it works. Don’t forget, prior to compaction, sweep clean the surface of the pavers.

Q. How well do interlocking concrete pavements perform over the long term?
A. One of the best performance examples for streets and sidewalks is found in North Bay, Ontario, which are now over 20 years old!

Q. What is the maximum slope for concrete pavers?
A. For non-vehicular applications such as embankment stabilization, the maximum slope is determined by the angle of repose of the bedding sand, typically around 35 to 38 degrees. For vehicular traffic, the highest slope in use is 18% (about 10 degrees) in a street in Colma, California. Special consideration is given to the drainage of the bedding sand at the bottom of the slope.

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