Repair Systems — Concrete & Structural Defects
Crack injection ports
Technical product reference for surface-bonded and mechanical injection ports used in concrete crack injection — covers port types, maximum injection pressures, port adhesive systems, and crack measurement tools for PU and epoxy injection in Australian construction.
Port selection and correct injection sequence
Surface-bonded ports suit most crack injection applications on accessible flat surfaces at pressures below 0.5 MPa. Mechanical hammer-in ports are used for thick structural elements, overhead applications, and where injection pressure exceeds 0.5 MPa. Both types require port adhesive to bond the port and seal the crack surface between ports before injection begins.
Product Reference
Individual products — one card each — scroll to view all
Sika / Mapei / Fosroc
Surface-Bonded Plastic Injection Port — Standard Low-Pressure Crack Injection
Surface-bonded plastic injection port — low-pressure crack injection hardware
Surface-bonded plastic injection ports are the most common port type for crack injection in Australian remedial building work. A small plastic nipple with a flange base is bonded directly over the crack trace using a fast-setting epoxy paste adhesive (Sika Monotop 623, Fosroc Nitomortar FC, or matched brand port adhesive). Ports are spaced at 100–300 mm centres depending on crack width — closer spacing for fine cracks below 0.2 mm.
Hilti / DCP Chemprox / Specialist Supply
Mechanical Hammer-In Injection Port — Drilled and Inserted into Crack
Mechanical hammer-in injection port — high-pressure crack injection hardware
Mechanical hammer-in injection ports are installed by drilling a hole (typically 12–16 mm diameter) through the concrete surface into the crack plane at an angle of approximately 30–45 degrees to the face, then hammering a tapered plastic or steel port to seal the hole. This creates a port mechanically locked into the concrete, resisting injection pressures up to 1–2 MPa without debonding. Used for thick structural elements, high-pressure injection of deep cracks, or overhead injection where surface-bonded port adhesive bond strength is inadequate.
Sika / Fosroc / Mapei
Crack Port Adhesive — Fast-Setting Epoxy Paste for Port Bonding and Surface Sealing
Fast-setting epoxy paste — port bonding and crack surface sealing — injection system accessory
Port adhesive is a fast-setting 2-component epoxy paste performing two functions in a crack injection job: (1) bonding the surface port flange to the concrete directly over the crack, and (2) sealing the crack surface between ports to prevent resin bypassing the port and running along the crack surface before penetrating. Mix and apply with a palette knife or tongue depressor — build a small fillet around the port base to ensure contact across the full flange. For the surface seal between ports, apply a bead of 10–15 mm width centred on the crack trace.
Sika / DCP Chemprox / Engineering Suppliers
Crack Width Gauge — Comparator Card and Feeler Gauge for Pre-Injection Classification
Crack classification and measurement tool — inspection kit item — pre-injection mandatory
Accurate crack width measurement before injection determines resin selection, port spacing, and whether injection is feasible. Crack measurement tools used in Australian practice include: (1) Crack comparator card — a plastic card printed with reference line widths from 0.05 mm to 3 mm, held against the crack for a visual match; (2) Crack width gauge — a set of thin calibrated feeler strips inserted into the crack opening to measure width directly. This is a classification tool, not a manufactured product in the traditional sense — but it is a required item in any crack injection scope.
Mapei
Mapei Rubber Band Syringe
Low-pressure injection syringe — crack injection tool
The Mapei Rubber Band Syringe is a low-pressure injection tool for crack injection of two-component PU foam and epoxy injection resins in concrete and masonry. The rubber band spring mechanism provides a constant, controlled low-pressure injection force that avoids the overpressure risk of mechanical or pneumatic injection equipment. Low-pressure syringe injection is suitable for hairline and fine cracks where controlled material flow is required.
System Comparison
Concrete cracking — confirm all selections against the current manufacturer TDS before specifying.
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Do not confuse crack injection ports with:
- The injection resin itself — crack injection ports are the hardware delivery system (the valve and fitting through which resin enters the crack); the PU or epoxy injection resin is the separate reactive chemical product that fills the crack void — both must be specified independently
- Crack width gauges and comparator cards — these are diagnostic and measurement tools used before injection to classify crack width and select resin; they are part of the inspection kit, not the injection system, and do not form part of the port installation
- Epoxy paste for crack stitching bars — fast-setting epoxy adhesive used to grout structural stitching bars (Hilti HIT-RE 500 V3, Ramset Chemset) is injected into drilled cylindrical holes at full diameter; crack port adhesive is a surface paste bonding the port flange over the crack trace — completely different application
- Mechanical expansion anchors and plugs — concrete expansion anchors (Hilti HSA, Dynabolt) are installed into drilled holes for structural load transfer; mechanical injection ports are also drilled and inserted but function as sealed pressure fittings, not load-bearing anchors
- Helifix crack stitching bars — helical stainless steel bars (HeliBar) grouted into saw-cut slots across crack planes provide tensile resistance; they are a structural stitching system, not an injection port, and require a different preparation method (slot cutting, not port drilling)
Disclaimer
This page provides general technical information only. Final product selection must be confirmed against the current manufacturer TDS, project specification, substrate condition, and applicable standards. Do not rely on this reference as a substitute for professional engineering advice.