How to choose between installing poured concrete vs concrete pavers on your driveway
Poured concrete is great for footings and foundation walls. However, a 4'' concrete slab will not carry the same weight distribution as interlocking concrete pavers.
Interlocking concrete pavers carry over twice the pounds per square in in weight because they interlock in three different ways. This is why they are more practical for vehicular (driveways) applications
Horizontal interlock - this is the pavers ability to resist side to side shifting movement, it is created by the pattern of the pavers along with the tightness of that pattern and at the edges of the project edge restraints. They can be aluminum edge restraints specifically designed for this application set in place with 12" spikes. Edge restraints can also be the concrete foundation that the patio is up against, a curb etc.
Vertical interlock - this is the pavers ability to resist moving either up or down. Vertical interlock is primarily achieved by the tightness of the pattern and the quality of the preparation of the sub-base and base materials under the pavers.
Rotational interlock - this is the pavers ability to resist rotating. We've all experienced stepping on a piece of flag stone only to have one side lift up. That is the flag stone rotating. Creating this type of interlock is achieved through the tightness of the pattern and the ratio of the paver height to length. That's why flagstone lifts, no rotational interlock.
Pavers in the Unites States are only considered a paver if they meet requirements set forth by the ASTM (American Society of Testing and Materials):
An average compressive strength of 8,000 psi or greater
An average absorption no more than 5%
Resistance to at least 50 freeze-thaw cycles with average material loss not exceeding 1%
Conformance to abrasion resistance tests
A length to thickness ratio of no more that 4:1 (that's right a paver that has a side longer that 4 times it's height is no longer a paver - it's just a slab of concrete)
Unsightly pavers can be replaced
They can be picked up to allow for a utility line or pipe to be repaired, and then placed back down with no structural or visual notice
So why do developers and builders continue to pour concrete driveways instead of installing pavers when it is arguably the most important area of concrete flatwork? This area carries the most load, is the most costly to install and repair, and has the most potential to fail.
The simple answer is that it is cheaper for them. The cost for most concrete driveways ranges around $7.50/sq. ft. with the life expectancy only around 10-20 years. It is extremely likely to develop cracks, even within months of installation.
In fact, the installation of a concrete driveway actually plans for this cracking by placing expansion joints to try to direct the crack when it happens along a defined line. Concrete can also chip which cannot be easily repaired without noticeable unsightly patches.
Concrete pavers are laid by hand, so the installation takes longer and costs more up front than pouring concrete. As a base reference the installation of a paver driveway will typically cost between $15 and $20 per square foot. However, because they are easier to maintain, environmentally friendly, and have a longer life expectancy than poured concrete they work out being a better option for homeowners in the long run.