What is H-20/HS-20 Loading?

AASHTO's H-20 and HS-20 are live load ratings applied to the design of bridges or other suspended items (e.g. lids for concrete vaults).
Diagram of H-20/HS-20 truck loading limitations.
Because the pavers sit on a flat aggregate surface, they are not subject to the same bending moments and shear, and therefore will not collapse under the applied loads. Paver systems are actually designed for thousands, if not millions, of ESAL, which represent the estimated number of vehicles that pass over the surface during the design life.
In terms of being able to withstand the surface pressure exerted by the truck tires, the heaviest gross axle weight (GAW) for a firetruck that is allowed is 24,000 pounds. Assuming standard tires are used (even though Super Single tires are required) the maximum weight on each of the wheels is 12,000 pounds (24,000 pounds/2 wheels).

Using a conservative contact area on the bottom of the wheel of 8 inches square, the pressure exerted by each front wheel is 187.5 psi (12,000 pounds/64 square inches). Any concrete paver offered under the Belgard line is made in accordance with ASTM C936, which calls for an average compressive strength of 8,000 psi with no individual unit being less than 7,200 psi.

Simply put, Belgard pavers are on average 40 times stronger than required to withstand the surface pressure that would be exerted under the most extreme conditions, and therefore exceed the requirements of H-20 and HS-20 loading if the pavement has been properly designed for the site conditions including traffic loading and subgrade strength.

See Designing the Pavement System on page 6 for more details.
Fire truck parked on interlocking concrete pavers.
Belgard Commercial: Aqua Bricloc®