Repair Systems — Concrete & Structural Defects
Polymer-modified repair mortars
Technical product reference for polymer-modified cementitious repair mortars for filling crack gaps and patching spalled surfaces in concrete elements after settlement crack repair — concrete and concrete block substrates only; not for heritage brick or stone masonry.
4
Products covered
Concrete only
Substrate
> 30 MPa
Strength
Post-stitch fill
Sequence
Settlement Cracks — Product Categories
Product Reference
Individual products — one card each — scroll to view all
4 products — 3 visible, scroll for more
Sika Australia — SikaTop-121
Sika SikaTop-121
Two-component polymer-modified cementitious repair mortar
2-component PM> 30 MPaConcrete only
Best for
- Two-component polymer-modified mortar — cementitious binder + acrylic polymer
- Compressive strength > 30 MPa at 28 days
- Suitable for vertical and overhead application — anti-slump formulation
- Sika Australia — national direct and distributor supply
Avoid where
- CONCRETE ONLY — not for use in brick, stone, or heritage masonry (use lime-based…
- Do not apply to a crack that is still actively moving — repair mortar…
- Bond coat (SikaBond or equivalent) required on all concrete surfaces before mortar application
- Depth per coat limited to approximately 25 mm — build up in layers for…
Key application info
- Thickness / layer
- N/A
- Application temp
- N/A
- Primer / bond coat
- N/A
- Pack size
- N/A
- Application method
- N/A
- Vertical / overhead
- Yes
- Substrate
- N/A
- Setting
- N/A
Key warnings
CONCRETE ONLY — not for use…Do not apply to a crack…Bond coat (SikaBond or equivalent) required…Depth per coat limited to approximately…
Ardex Australia — RA55
Ardex RA55
Rapid-setting single-component polymer-modified cementitious mortar
Rapid setSingle component> 25 MPa at 4 hrs
Best for
- Single-component — water only addition — consistent mix quality
- Rapid strength gain: > 25 MPa compressive strength at 4 hours
- Polymer-modified — improved adhesion and reduced shrinkage vs plain cementitious
- Ardex Australia — national supply
Avoid where
- CONCRETE ONLY — not for heritage brick masonry or sandstone
- Rapid set reduces working time — mix only as much as can be placed…
- Bond agent required on prepared concrete surface before application
- Do not apply to cracks still experiencing movement — rapid-set mortar has low tensile…
Key application info
- Thickness / layer
- N/A
- Application temp
- N/A
- Primer / bond coat
- N/A
- Pack size
- N/A
- Application method
- N/A
- Vertical / overhead
- N/A
- Substrate
- N/A
- Setting
- Rapid-set
Key warnings
CONCRETE ONLY — not for heritage…Rapid set reduces working time —…Bond agent required on prepared concrete…Do not apply to cracks still…
Fosroc Australia — Renderoc HB40 Plus
Fosroc Renderoc HB40
Single-component high-strength cementitious repair mortar
Structural patch — confirm with Parchem
Best for
- Fosroc — distributed nationally through Parchem Construction Supplies
Avoid where
- CONCRETE ONLY — not for brick masonry, sandstone, or heritage masonry
- Bond agent required before application to existing concrete — confirm bond agent for selected…
- Settlement must be confirmed dormant before mortar application
Key application info
- Thickness / layer
- N/A
- Application temp
- N/A
- Primer / bond coat
- N/A
- Pack size
- N/A
- Application method
- N/A
- Vertical / overhead
- N/A
- Substrate
- N/A
- Setting
- N/A
Key warnings
CONCRETE ONLY — not for brick…Bond agent required before application to…Settlement must be confirmed dormant before…
Mapei Australia — Mapegrout Fast-Set
Mapei Mapegrout Fast-Set — Rapid Repair Mortar for Concrete
Single-component rapid-setting fibre-reinforced repair mortar
Rapid-set + fibreSingle componentConcrete only
Best for
- Single-component — water only addition — polypropylene fibre reinforcement
- Rapid strength: > 20 MPa at 3 hours, > 40 MPa at 28 days
- Reduced plastic shrinkage cracking from fibre reinforcement
- Mapei Australia — national supply through trade distributors
Avoid where
- CONCRETE ONLY — not for brick masonry or other masonry substrates
- Rapid set reduces working time — plan application in manageable batches
- Bond coat required on prepared concrete substrate before application
- Fibre reinforcement is anti-shrinkage only — does not replace structural reinforcement or stitching in…
Key application info
- Thickness / layer
- N/A
- Application temp
- N/A
- Primer / bond coat
- N/A
- Pack size
- N/A
- Application method
- N/A
- Vertical / overhead
- N/A
- Substrate
- N/A
- Setting
- Rapid-set
Key warnings
CONCRETE ONLY — not for brick…Rapid set reduces working time —…Bond coat required on prepared concrete…Fibre reinforcement is anti-shrinkage only —…
System Comparison
Concrete cracking — confirm all selections against the current manufacturer TDS before specifying.
| Brand | Product | Type | Key specification |
|---|---|---|---|
| Sika Australia — SikaTop-121 | Sika SikaTop-121 | Two-component polymer-modified cementitious repair mortar | Two-component polymer-modified mortar — cementitious binder + acrylic polymer |
| Ardex Australia — RA55 | Ardex RA55 | Rapid-setting single-component polymer-modified cementitious mortar | Single-component — water only addition — consistent mix quality |
| Fosroc Australia — Renderoc HB40 Plus | Fosroc Renderoc HB40 | Single-component high-strength cementitious repair mortar | Fosroc — distributed nationally through Parchem Construction Supplies |
| Mapei Australia — Mapegrout Fast-Set | Mapei Mapegrout Fast-Set — Rapid Repair Mortar for Concrete | Single-component rapid-setting fibre-reinforced repair mortar | Single-component — water only addition — polypropylene fibre reinforcement |
Do not confuse PM repair mortars with:
- Lime repointing mortars (NHL, lime putty) — lime-based mortars are for masonry joint reinstatement in brick, stone, and heritage masonry; PM cementitious mortars and lime mortars are for completely different substrates and must never be substituted for each other; PM mortar in heritage brick causes brick face spalling
- Epoxy injection resins — low-viscosity epoxy resins are injected under pressure into fine cracks; PM mortars are trowel-applied surface fills for visible crack gaps and spalled areas; they serve different functions in the same repair sequence
- Non-shrink cementitious grout (Sika Grout-215, Conbextra GP) — non-shrink grouts are flowable, poured materials used for equipment baseplate bedding, void filling under footings, and anchor grouting; they are not trowel-applied patch materials and are not suitable for vertical crack fill applications
- Epoxy repair mortars (Sikadur 31, Sikadur 41) — epoxy aggregate mortars are aggregate-filled two-component epoxy materials for high-stress chemical-resistant patches; they are significantly more expensive than PM mortars and are specified where epoxy chemical resistance is required; most settlement crack fill applications do not require epoxy mortars
- Render (Rockcote, BGC) — cementitious render is applied to the full surface of a masonry or concrete wall; it is not used to fill individual settlement cracks or spalled spots in isolation; render is a surface coating treatment, not a crack fill mortar
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.
Concrete & Structural Defects
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Settlement Cracks
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Structural Anchors
Structural stitching — completed before mortar crack fill
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Lime Repointing
Lime mortars for masonry — not for concrete elements
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