What are Interlocking Concrete Pavers (ICP)?
What are Interlocking Concrete Pavers? Interlocking Concrete Pavers, or more commonly called Pavers, Paving Stones or Interlocking Paving Stones, are precast concrete units that come in various shapes, colours, sizes and thicknesses.
What is that purpose? The purpose of Pavers is to provide an easy-to-build and attractive concrete pavement surface for applications such as:
and many more.
How does it work?
When installed correctly (Don't worry, we can help ensure proper installation.), the individual paver units create a unified, interlocked, flexible pavement that distributes heavy surface loads across the paver units and the structural base underneath the pavement by a process called "Shear Transfer." There are seven components of an Interlocking Concrete Pavement System starting from the bottom to top:
Compacted Soil Sub-grade: The Soil Sub-grade is what is found at the bottom of your excavation and usually consists of Sand/Gravel, Silty Soils or Clay. Compaction techniques may vary depending on the soil type.
Geotechnical Fabric: Geotechnical Fabrics can be a Non-Woven, Woven or Biaxial. The purpose of these fabrics is to prevent the sub-grade soil from mixing with the Structural Base Gravel and to provide additional strength to the structure by increasing load distribution. Geotechnical Fabrics are a must for silty and clay soils but are optional for better soils such as sand and gravel but recommended.
Structural Gravel Base: Structural Gravel base traditionally consists of a 3/4" minus Road Base or Road Crush. Road Base is a gravel crusher product that provides angular rock so that it creates a robust and interlocking structure and contains coarse to fine rocks and sands. An increasingly popular option is to use a 3/4"-1" clear crushed rock that requires less compaction, is easier to install and provides much greater frost protection. The depth of the Gravel Base may vary depending on the expected traffic and the sub-grade soils. A Driveway on top of a Clay Soil sub-grade will require more Structural Gravel Base than a pedestrian pathway on a sand/gravel sub-grade. We can help you determine how much to use.
Bedding Layer: A bedding layer consists of a 1" thick (no thicker) washed concrete sand or a 3/8" to ¼" clean stone, which is spread and levelled to provide a consistent surface for the paver units.
Paver Units: These are the "wearing course" that has direct contact with people, vehicles and the natural environment. As mentioned, they come in numerous sizes, colours, shapes and thicknesses. An 80-100mm thick paver unit is recommenced for heavier traffic such as Driveways and Parking Lots, while a 60mm thick unit is great for pathways and patios.
Sand Filled Joints: The space between the paver units are called "Joints." We fill the joints with a fine natural sand or a polymeric sand, which is a manufactured sand that comes in multiple colours. The Joint Sand is what "locks" the units together and is what is responsible for allowing heavy loads to be distributed widely to the surface beneath to resist movement.
Edge Restraints: Edge restraints ensure that there is no lateral movement between the pavers; this could be the foundation of your house, an existing concrete curb or edge restraints that are installed made from plastic, aluminum or poured-in-place concrete.
How does it compare to Pour-In-Place Concrete and Asphalt?
Flexible vs. Non-Flexible: There is an old saying that there are two types of concrete, "Cracked" and "Going to Crack." Pour-In-Place Concrete is considered a "Non-Flexible Pavement," which is destroyed over time by freeze-thaw cycles and frost heaves because they resist the earth's movements, even when expansion and contraction joints are installed. Asphalt Pavement, although considered a "Flexible Pavement," also cracks during freeze-thaw cycles and frost heaves as well as "rut" under heavier loads such as parked vehicles because it does not distribute loads as effectively as pavers. A "Flexible Pavement," like Pavers, works with nature as it moves and adjusts to the different seasons and temperatures.
Initial Price: Pour-In-Place Concrete and Asphalt is generally less expensive as it can be installed in a short amount of time. Concrete will require steel rebar and is challenging to install in very hot or in rainy weather as it requires the proper time and temperatures to cure properly. Pavers may be more expensive at first but will generally last longer and are very easy to maintain or repair if issues arise.
Can you "Do-It-Yourself"? Cast-In-Place Concrete generally requires a professional to do it as it has a steep learning curve and special tools. Asphalt may require a special machine that ensures the asphalt is installed at the right thickness and is level. Pavers require very little education and require standard tools that you either have already or can easily be purchased or rented.
In upcoming posts, we will go into more detail about the specifics of paver installations.
Feel free to contact us at Island Cache Stone Company for any questions or design ideas. We are more than happy to show you around the yard and demonstrate how to use any products.
About the Author: Cory Klein is a Co-Founder and Chief Excellence Officer for Island Cache Stone Company. He has an extensive background in Civil Construction and Hardscape Landscaping. He also owns and operates a Hardscape Landscaping business called Northern Earthworks Solutions.
180 River Road
Prince George, BC