To be considered a paver in the United States, they need to meet all the requires that have been determined by the American Society of Testing and Materials. More information can be found at their site http://bur-han.ca/landscaping-installations-repair/paver-installation-and-repair/.
The current classification for a paver is ASTM C936.
A paver must meet the following characteristics:
- The average compression strength is 8,000 psi or more
- The absorption is 5% or less
- There needs to be a resistance of 50 freeze and thaw cycles, and the average material loss cannot exceed 1%
- It must meet abrasion resistance tests
- The length to thickness ratio should be no more of 4:1. If the side is four times higher than the height, it is not considered a paver.
- Old and rusty pavers need to be replaced
- They can be picked up to a pipe, or another item can be returned and put back down. No one will know that it was moved.
- There are different types of concrete including stamped, textured, and exposed aggregate, among other types.
- Contractors work with concrete that is between 3500 and 4500 psi and has a slump that ranges between 3 and 7. Five or six is good depending on the weather.
- Cracking is a feature of the concrete and not a design flaw.
- Different batches may produce different colors.
- It is hard to perform quality control unless a sample is taken from each bag mixed.
- Putting a wire or a pipe under the concrete may need expensive equipment in the future including a jackhammer.
Let’s look at which is the best when working with concrete.
Poured concrete is good for compression loads but is not too good for tensile loads. Concrete is great for making decks as well as foundation walls. There will be some cracks, but this is okay.
It is not good when being poured 4 inches thick and if it is going to be driven on. Once this happens, it is going to be difficult to stop it from cracking.
Concrete walkways that have cracks
This is a picture of what stamped concrete with cracks looks like.
Qualifications of good pavers
Pavers are good at these loads. They interlock in 3 different ways.
Horizontal Interlocks- the paver needs to be able to resist the concrete from moving from side to side. The pattern will be tight, and the edges will show restraint. The edges can be aluminum, and they are designed for use with 12-inch spikes. The edge restraint can be the concrete foundation that may be up against the curb of the patio.
Vertical interlocks- the pavers need to resist the up and down movement. This is done by the tightness of the pattern and the preparation of a sub-base and the base material.
Rotational interlock- the pavers will need to resist rotating. If we step on a piece of, it often lifts up and is considered to be rotating. This is done with the tightness of the pattern as well as the power of the paper. That causes the flagstone to lift, and there is no rotational interlocking needed.
Pavers are often low maintenance. Just clear the leaves and debris away a couple of times a year, and the project will look good. If they are installed properly leaves will not grow through them. There is a whole blog article for this.