FAQS - Paving Stones
Is Calstone a local California based company?
Yes! Calstone is a family owned company originating in the Bay Area, proudly celebrating our 70th year providing concrete products to our neighbors throughout California and other western states.
What Are Calstone Interlocking Concrete Paving Stones (Pavers)?
The Basic installation process works like this: pavers are placed on one inch of bedding sand over a compacted aggregate base. (The thickness of the base will vary depending on the application, Soil stabilization fabric may also be added to increase stability.) Pavers and sand are retained using edge restraints. Commonly used edge restraints include concrete curbing, plastic edge restraints, aluminum edge restraints, and concrete edge bond beams. The pavers are compacted into the bedding sand using a vibratory plate compactor. Sand is then swept into the joints and again compacted, creating “interlock.”
Regardless of which Calstone paver shape, color, or pattern you choose, installation involves interlocking the pavers with joint sand. This provides pavement superiority in a multitude of ways. The pavers distribute traffic loading over a greater surface. The pavers remain flexible and can withstand minor and major movements of soils. Maintenance and repairs (if required) are simplified because no mortar is used in the installation process.
Can I expect every paving stone to be perfect?
Some of your pavers may have slight surface variations. Although we attempt to make every paving stone perfect there will always be a small percentage that has imperfections including de-molding marks, incidental scuffing, flashing, efflorescence, and some color variation. This is normal and is part of the manufacturing process that gives the stones individuality. Although we have an extensive quality control process, the paving stones are manufactured out of natural materials, then packaged and shipped to their final location. During the manufacturing and shipping process, up to 3% of the paving stones in any given shipment will have imperfections.
Are paving stones slippery?
No. In fact, Calstone paving stones exceed the Caltrans standards for friction coefficient (slip and skid resistance) for freeways and highway constructions. Pavers also surpass the slip resistance standards established by the American Disabilities Act.
What is that white stuff on my pavers?
Occasionally, some pavers may have a whitish residue upon them. The whitish colored residue is called efflorescence. Efflorescence is a natural by-product from the cement hydration process and can be found in any concrete or mortar product. Calcium oxide inside the paver reacts with water in the capillaries and forms calcium hydroxide. This seeps to the surface and reacts with the carbon dioxide in the air to form calcium carbonate, a whitish residue. When moisture on the surface evaporates, the white efflorescence becomes visible.
If efflorescence is present, it will wear off over the course of time with traffic and the elements. If you wish to speed up the removal of efflorescence, Calstone recommends the Aldon Paver Restore.
Why are some of my pavers scuffed?
Pavers become scratched and scuffed, or “bruised”, in many ways before and during installation. These marks are normal and will disappear over time. Common causes are abrasion during transportation, handling scratches during placement, and scuffing during the vibration compaction process. The vibration compaction process is likely the most stress the pavers will ever see.
What are Calstone’s antiquing standards?
Calstone employs two different antiquing methods that are specific to the product being treated. The two methods we use are barrel tumbled antiquing and hammer antiquing. Regardless of the method used, our objective is to randomly distress the stones to in order to achieve an imperfect aged appearance. All antiqued stones will have at least one, and possibly all of the following characteristics
- Broken edges
- Broken corners
- Temporary scratches and muted color vibrancy
Why are my pavers fading?
There are several reasons why pavers appear to be fading. Efflorescence is the primary cause for Duraface premium pavers. Efflorescence is a natural by-product of the cement hydration process and can be found in any concrete or mortar product. Calcium oxide inside the paver reacts with water in the capillaries and forms calcium hydroxide. This seeps to the surface and reacts the carbon dioxide in the air to form calcium carbonate, a whitish residue. When moisture on the surface evaporates, the whitish efflorescence becomes visible. Dirt, dust, and stains are other reasons that give the appearance of fading.
Efflorescence and most stains can be removed by using Aldon Paver Restore. Dirt and dust can be removed with a proper cleaning. There are many articles and webinars, including cleaning and maintenance information, found at www.icpi.org/calstone. All pavers should be clean prior to sealing
Why do my paving stones change color throughout the day?
Paving stone colors can change depending on the amount of sunlight that hits them. For instance, bright mid-day sunlight will lighten the color and dusk or dawn will darken the color. When choosing one of Calstones full range of blended colors, check the area where the pavers will be installed throughout the day. It’s best to check in bright sunlight, filtered sunlight and even at night when landscape lights shine on the area by using a sample of the paving stone color or colors you are considering. Calstone will provide free samples. Samples are available for pick up at any of our manufacturing facilities. To contact a plant nearest you click here.
The photos below are our Antiqued Flat Top in the color Gray Charcoal Tan.
Do I Need To Seal My Calstone Pavers?
Sealing is an option. But sealing the pavers does have some advantages. Sealing your pavers will:
- Make clean-up of oil, food, or vegetation stains easier.
- Help stabilize the joint sand from being washed out by rains or heavy cleanings.
- Help prevent efflorescence from occurring or recurring.
- Help prevent vegetation growth.
- Darken and brighten the color pigments in your pavers.
Sealing your pavers can take place immediately upon completion of installation or at any time in the future provided the pavers are clean and weather permitting. The area to be sealed should be cleaned and allowed to thoroughly dry (approximately 3 - 5 days of warm weather) before the application of the sealer can take place. Although pavers may appear dry on the surface, it is very important to wait the prescribed drying time before the application of the sealer.
How do I clean my pavers?
When properly installed, pavers require very little maintenance, but eliminating many reasons why pavers need to be cleaned is important. This should include preventing weed growth which is topical, by pulling weeds or using polymeric joint sand. Eliminating sources that stain pavers such as leaking oil from vehicles, sprinklers hitting the area which can cause efflorescence, food stains, and organic staining from trees and landscaping. There are several cleaners on the market that can address each of these particular issues. Contact a Calstone sales representative for specific suggestions on condition of your pavers.
For additional information, here is the link to the ICPI Tech Spec on cleaning pavers: Tech Spec #5 (Cleaning, Sealing and Joint Sand Stabilization of Interlocking Concrete Pavement). Click Here
Can I lay pavers over my existing asphalt or concrete?
Yes, you can, but only under certain conditions. First, the existing pavement must be in good condition. If the existing pavement is in poor condition (major cracks, heaving, settling, potholes, etc.), it is wiser to start over and build the base system up properly. It is also important to check whether there is enough threshold clearance to accept a 2 3/8” thick paver plus the 1” sand bedding course. Another consideration when installing over an existing surface is whether the pavers can be successfully joined to meet other existing pavements such as garage surfaces and sidewalks. If you find that your existing pavement meets these conditions, follow the normal installation methods with a few additions:
- Add a woven geotextile fabric over the existing pavement and under the sand bedding course. This will protect the sand from migrating into existing or future cracks and failures of the previous pavement.
- Use an adequate edge restraint to hold the pavers and sand bedding course in place (this may require additional construction outside the area of existing pavement).
- Remove enough of the existing pavement to allow the pavers to gradually taper down to adjoining surfaces. Also, excavate enough material to allow proper thickness and compaction of the base material to support anticipated traffic.
- Ensure that the bedding sand layer has proper drainage.
What type of sand do I need to use between the pavers?
Calstone recommends using Calstone standard joint sand or polymeric sand.
Should I use polymeric sand?
Polymeric sand is a mixture of polymer binders and specialty joint sand which is installed almost identical to using regular paver joint sand except for the application of water. It is durable, long-lasting and easy to maintain. It helps prevent erosion due to the wind, rain, and freeze-thaw cycles along with deterring weed growth and damage caused by burrowing insects. Calstone recommends Alliance polymeric sand for a variety of uses including pool decks, patios, footpaths, driveways, parking spaces, etc. It is available in gray or beige colors.
Would It Be Better To Mortar The Pavers Into Place?
No. Setting the pavers in wet mortar or concrete will eliminate the flexibility and superiority of sand set installation.
What Type of sand do I need to use under the pavers?
Use a course, hard, angular washed sand conforming to ASTM C-33 (washed concrete sand). This type of sand will not deteriorate over time and will drain water well. DO NOT use stone dust, limestone screenings, loam, rounded/fine sands, or decomposed granite.
How Do I Cut The Pavers?
The two basic methods for cutting pavers are either with a diamond saw blade or mechanical paver splitter. Because of their high strength, pavers are hard to cut. A paver splitter, with a little practice, will make a nice cut but cannot make smaller precision pieces. For more precision cuts and difficult pieces around downspouts, drains, utility boxes, etc., a brick saw using a wet diamond blade is recommended.
Important note: If wet cutting, be careful to not drip or spray the contaminated water onto the pavers. This type of staining is extremely, if not impossible to remove. Pavers should be rinsed thoroughly before placing them into the laying field.
Where do I find paving stone installation guidelines?
For proper installation procedures visit: www.icpi.org/Calstone. Choose Tech Spec #2 (Construction of Interlocking Concrete Pavements).