Rubber Sole on a Wacker

[Martin B]

Is it advisable to use the rubber sole on a Wacker when bedding in the blocks ? My worry is that not using one will lead to damage or scratching of the blocks.

Thanks for your help and such a great website.

Martin B

[suki]

if u spread the kiln around genourously where u are about to wacker then the kiln will cusion the plate from the blocks, i kiln every job and wacker without a rubber plate and never have a problem. i only use the rubber on clays.

[84-1093879891]

Most concrete blocks don't ned the rubber mat fitting to the base of the vib plate, as they are tough enough to withstand a good rattling, and, with the tumbled types, even if there was a minor amount of damage, you'd never notice. The flexible bedding actually helps absorb the force of the vibration, and so the blocks are spared the worst effects of the plate compactor. Consequently, rigid-bedded blocks should not be vibrated once the bedding/jointing has cured.

Clay pavers are often considered to be more brittle than their concrete cousins, and so many contractors choose to use the rubber mat when consolidating, but it's not always necessary - as Suki says, a good, generous covering of the jointing sand can provide a sufficient degree of cushioning, and the only real danger of spalling clay pavers is when, because of the slight deformations that are inherent with any kiln-fired product, two adjacent bricks are in direct contact, and so rattle against each other. Because concrete pavers have a high level of dimensional accuracy (usually), the odds on two pavers being in direct contact is much less, and so spalling is less likely.

But, if you want to err on the side of caution, then you should fit the rubber mat before final consolidation.