P03.02
MavJoint — control joint filler
MavJoint JF is a semi-rigid polyurea filler for saw-cut control joints in industrial concrete. It supports wheel loads across the joint and keeps debris out. It is not a caulk, not an expansion joint sealant, and not a crack chaser.
- State what a control joint filler does and what it must never be asked to do
- Give the target hardness range and why it matters
- Answer an expansion joint request correctly and offer the right alternative
A filler with one job
MavJoint JF fills saw-cut control joints in industrial concrete floors so the joint can carry wheel loads across its edges, keep debris out of the cut, and still shrink modestly as the slab continues to cure. That is the entire job. Asked to do anything else — bridge an expansion joint, seal a cove, chase a crack — it is the wrong product and it will fail in a way the customer remembers.
Installation facts
| Item | Standard |
|---|---|
| Joint type | Saw-cut control joints in industrial concrete floors — never expansion joints |
| Hardness target | Semi-rigid polyurea, typically Shore A 80–90 |
| Saw-cut prep | Dry, dust-free, roughened sidewalls; remove any laitance |
| Trimming | After full cure, flush to the slab with a sharp razor blade |
| Old, long-open joints | Accumulated debris and edge damage mean materially worse bond than a joint filled fresh — prep is critical, and say so up front |
Say it out loud, then check yourself
- 01What is the primary use case for MavJoint JF?
A semi-rigid polyurea filler for saw-cut control joints in industrial concrete floors. It supports wheel loads across the joint, keeps debris out of the saw-cut, and allows modest ongoing joint shrinkage. Not a caulk, not an expansion joint sealant, not a crack chaser.
- 02What Shore hardness does a semi-rigid polyurea filler target, and why?
Shore A 80 to 90. That range is stiff enough to carry hard-wheel forklift loads across the joint without spalling the concrete edges, yet soft enough to accommodate the small shrinkage of a cured control joint. Below Shore A 70 the filler squeezes out under wheels; above Shore A 95 the concrete edges chip.
- 03A contractor asks if JF can bridge a 3/4-inch expansion joint.
It cannot. Expansion joints are designed to move, and a semi-rigid polyurea will tear or debond. Recommend a proper elastomeric expansion joint sealant with backer rod, and keep MavJoint JF for control joints.
Takeaways
- Control joints only. An expansion joint is designed to move — a semi-rigid filler will tear.
- Semi-rigid polyurea fillers target Shore A 80–90.
- Trim after full cure, flush to the slab with a sharp blade.