The more the slump, the weaker the concrete. Pavers are said to have zero slump.
Pavers are made from a very dry mix of gravel, sand, cement and color. Since there is very little water, the mixture is moved on conveyor belts and then funneled into the paver mold. A press is inserted into the mold and vibrated at the same time. The high pressure and the vibration causes the water to set the cement and creates a bind between the aggregate. When the mold is moved away, the pavers are in their finished state.
Pavers and Pavement Strength
The strength of concrete is achieved in three main ways:
- The amount of water (the less water, the stronger).
- The amount of cement in the mix (the more cement, the stronger).
- The amount and size of aggregate (the bigger, the stronger).
A surface is tested for strength by placing a point load onto it and exerting a direct force until it fails. The pressure is calculated, and that is the failing point. Pavers need to withstand a minimum of 8,000 pounds per square inch (55,000 kPa) to meet industry standards. Usually when tested, they far exceed this minimum. Typical concrete from a concrete truck will produce a surface with a load strength of about 2,000 pounds per square inch (14,000 kPa).
That means a paving stone driveway is at least four times stronger than a regular concrete driveway.
And now you know! 🙂