Can paver cleaning damage the joints?

A paver joint is a line of sand between two units, and water moving across the surface can carry some of that sand with it. ICPI names the variables in one sentence, “The nozzle type and its distance from the paver surface influences the effectiveness of the cleaning as well,” and then says which spray spares the joint.

A wide spray, in ICPI's words, “prevents sand from being washed from the joints,” and a low angle of attack from that wide spray “will also reduce the risk of dislodging joint sand.” The reverse is the risk: water gathered into a narrow jet, or aimed steeply into the joint, is the case those lines are written to avoid.

Whether pavers can be pressure washed at all, and the pressure ICPI publishes for concrete pavers, are set out where the service page explains what a paver cleaning removes.

A dry-applied joint sand stabilizer is activated with water, and ICPI says how that water should arrive: “A narrow spray should not be used because it can dislodge sand from the joints.” It is the same joint risk a cleaning carries, written for the moment a stabilized joint is first wetted.

Stabilized sand that is left on the paver faces and cures there has to come off. ICPI: “Once it is moistened and allowed to cure on the surface, the sand will need to be removed with hot water. Some stabilizers may require removal with a wire brush or a pressure washer.” That cleanup is on the paver faces, and the spray guidance above still describes the risk to the joint beside them.

Joint stabilization is defined on its own page, and why sand leaves joints in rain and running water, apart from any cleaning, is answered at why sand washes out of paver joints.

The Brick Industry Association adds a risk that comes from the cleaner rather than the spray. In its technical note on brickwork and brick pavements it says “acid-based cleaning solutions may not be appropriate for pavements containing joint sand stabilizers or polymeric sand,” and its instruction is to check first: “Prior to selecting a cleaning solution for brick pavements, it is recommended to verify the compatibility of the cleaner with the paver manufacturer.”

That caution is written for clay brick pavements, and ICPI's Tech Spec 5, for concrete pavers, prints no matching line about acid and stabilized joints. For a stabilized joint, the cleaner's label and, on brick, the paver maker are where compatibility is checked.

ICPI lists cleaning itself when it describes what a stabilizer protects joint sand against: aggressive cleaning appears beside flowing water, wind and tire action. It also says “Stabilization benefits pavements subject to aggressive, regular cleaning.” The institute treats the cleaning, done hard and often, as something a joint has to survive.

A sealer plays a smaller part at the joint. ICPI says liquid sealers penetrate the joint sand to some extent and “secondarily provide some stabilization,” and whether that helps pavers keep their sand is answered at does sealing help pavers hold sand.

How stabilization and heavy rain meet at the joint is covered on the paver cleaning page under joint sand, weeds and the Naples rain. The trade's order for the surface itself, a cleaner first and pressure after, is on the sealing guide, and how steam compares with a pressure washer is at is steam cleaning better than pressure washing for pavers.