Frequently Asked Questions

Why do industrial floor control joint arrises keep spalling and what is the correct repair approach?

Joint arris spalling is caused by the repeated impact of forklift and vehicle wheels crossing the joint, particularly when the joint filler or sealant has deteriorated and no longer supports the concrete edge against impact. The wheel of a loaded forklift crossing a joint creates a downward and horizontal impact force on the top edge of the concrete slab at the joint — if the edge is unsupported by sealant, the concentrated stress at the edge causes fatigue cracking and progressive spalling. The correct repair approach is: clean and prepare the spalled area; repair the arris with Nitomortar PE to restore a sound, hard, well-defined edge; allow adequate cure before traffic returns; and then seal the joint with a semi-rigid joint filler (such as a polyurethane or epoxy joint filler) that supports the arris against wheel impact without being so rigid that it transmits restraint forces into the slab.

How do I prepare the concrete arris before applying Nitomortar PE?

The preparation of the concrete arris for Nitomortar PE repair involves saw-cutting the spalled area to a minimum depth of 10 mm to create a well-defined, square-edged repair area (avoiding feathered edges that would fail under wheel load), removing all loose, contaminated, and carbonated concrete by mechanical means (angle grinder with diamond cup wheel, or air chisel), cleaning the prepared surface with compressed air to remove all dust, and applying the Fosroc epoxy primer coat (mixed Nitomortar PE base coat or a dedicated epoxy primer) to the prepared joint face. The primer must be tacky (not dry) when the Nitomortar PE mortar is applied. The fresh mortar is then packed and trowelled into the repair area, shaped to recreate the original concrete profile, and struck off flush with the floor surface.

Is Nitomortar PE a joint sealant or a joint arris repair mortar?

Nitomortar PE is a repair mortar for restoring the physical shape and load capacity of the concrete arris at the edge of the joint — it is not a joint sealant. After the arris has been repaired with Nitomortar PE and the mortar has fully cured (typically 24 to 48 hours), a joint sealant must still be applied in the joint gap to provide flexibility, waterproofing, and hygienic sealing. The choice of joint sealant depends on the type of joint (control joint, construction joint, isolation joint) and the expected joint movement and wheel traffic. For industrial floors, a semi-rigid polyurethane or epoxy joint filler that provides edge support is typically specified. A sealant alone will not repair a damaged arris — the mortar repair must come first.