Frequently Asked Questions

When should Nitoseal Epoxy rigid crack filler be specified instead of a flexible sealant for a floor construction joint in a warehouse and what happens if the wrong type is used?

The specification of rigid Nitoseal Epoxy versus a flexible joint sealant for a floor construction joint in a warehouse depends on whether the joint is expected to experience any movement and what type of loading the joint surface must resist. A construction joint in an industrial warehouse floor slab may experience several types of movement and loading: differential vertical deflection between the two slab panels at the joint (the slab panels deflecting differently under point loads from forklift wheel loads — causing the joint faces to shift vertically relative to each other, a movement called shear displacement or differential settlement); thermal opening and closing of the joint (the slab contracts in cool weather and expands in warm weather — a continuous 20 metre slab panel can expand and contract by 1 to 2 mm seasonally, opening and closing the construction joint); and impact loading from forklift and pallet jack wheels running across the joint (wheels impact the joint edge as they cross, transferring concentrated impact loads to the joint filler and the concrete joint edges). Rigid epoxy filler (Nitoseal Epoxy) is appropriate for construction joints where: the joint edges are in direct wheel traffic paths and the joint filler must be hard and rigid to prevent pallet jack and forklift wheels from dipping into the joint and chipping the concrete joint edges (a phenomenon called joint edge spalling, which is the most common floor joint failure mode in Indian warehouses); the joint has no significant expected thermal movement (joints in temperature-controlled cold stores and climate-controlled facilities have minimal thermal movement); and the primary slab loading is gravity (vertical) with minimal shear displacement at the joint. Flexible sealant (Thioflex 600, Nitoseal MS600) is required when the joint has significant thermal movement or where the joint is an expansion joint rather than a construction joint. Using rigid epoxy in an expansion joint that is designed to move will result in the epoxy cracking within the first thermal cycle and the joint being unprotected — the cracked rigid filler acts as a hard aggregate that damages concrete joint edges when the joint opens and closes.

How is Nitoseal Epoxy mixed and applied to fill a construction joint in a concrete floor and what is the procedure for ensuring the joint is filled to the full depth?

Filling a construction joint in a concrete floor with Nitoseal Epoxy requires careful preparation of the joint and a systematic application procedure to ensure the epoxy fills the joint to the full depth (not just seals the surface) and achieves adequate adhesion on both joint faces. The procedure is: joint preparation — the joint must be clean, dry, and free of all dust, curing compound residue, oil contamination, and old failed filler; clean by routing (sawing a consistent width and depth profile along the joint with a joint router or angle grinder fitted with a crack-chasing blade — this creates clean, vertical joint faces of consistent width for the epoxy to bond to); vacuum or blow out all dust and loose material from the routed joint; check that the joint is completely dry (no moisture in the joint — epoxy adhesion to wet concrete faces is dramatically reduced); mixing — measure and combine the Nitoseal Epoxy base and hardener in the exact specified ratio (do not estimate — the two-component ratio is precise, and variation causes incomplete cure or altered properties); mix thoroughly with a stick or small paddle until a uniform colour without streaks is achieved (typically 2 to 3 minutes); application — for shallow construction joints (10 to 15 mm deep), the mixed epoxy can be poured directly into the joint from a mixing container and levelled flush with the floor surface with a flexible steel squeegee; for deeper joints (more than 15 mm deep), the joint must be filled in lifts (pour first lift to half depth, allow to achieve initial stiffness — typically 1 to 2 hours at 25 degrees Celsius — then pour second lift to the final surface level) to prevent shrinkage cracking from the heat of exotherm in deep single-pour epoxy; final levelling — tool the surface of the filled joint flush with the floor level with a trowel or flexible squeegee before the epoxy reaches its initial set. Traffic can typically resume after 6 to 12 hours of cure at 25 degrees Celsius.

Is Nitoseal Epoxy suitable for filling structural cracks in concrete beams and slabs or is a lower viscosity epoxy injection resin needed for structural crack repair?

The suitability of Nitoseal Epoxy for structural crack filling in beams and slabs depends critically on the width of the crack — wide surface cracks that are accessible from the face and can be filled by trowel or squeegee are appropriate applications for Nitoseal Epoxy; narrow cracks (below approximately 0.5 to 1.0 mm width) that penetrate through the full depth of the structural element require a low-viscosity injection resin (such as Nitofill SL polyurethane or a low-viscosity Nitofill epoxy injection resin) that can penetrate the full crack depth under low injection pressure. Nitoseal Epoxy at the trowel-applied consistency appropriate for floor joint filling is too thick (too high viscosity) to penetrate into fine cracks by gravity or simple hand pressure — it will fill the surface zone of the crack (the top few millimetres of the crack opening) but will not reach the full crack depth, leaving the majority of the crack un-filled and the structural objective of the repair (full depth crack bonding and load transfer restoration) unachieved. For structural crack repair, the correct product selection is: cracks wider than 3 to 5 mm at the surface — Nitoseal Epoxy can be pushed into the crack with a trowel or squeegee to fill the accessible surface zone, combined with low-pressure injection of a low-viscosity epoxy or polyurethane to fill the depth of the crack that is inaccessible from the surface; cracks of 0.3 to 3 mm width — low-pressure injection of Nitofill SL (polyurethane, flexible) or Nitofill epoxy injection resin (rigid epoxy, low viscosity) through surface-mounted ports or drilled packers is the correct technique; cracks finer than 0.3 mm — specialist ultra-low viscosity epoxy injection or pressure injection techniques may be needed, and the structural significance of such fine cracks should be assessed by the structural engineer to determine whether injection is necessary or whether surface sealing is sufficient.