Sika Sikadur-31 SBA S-04 IN
Cool-weather epoxy segmental bridge adhesive for bonding match-cast precast concrete segments into structural, watertight joints between +10C and +20C.
What is it?
A two-component, solvent-free thixotropic epoxy paste adhesive built specifically for jointing match-cast precast concrete bridge segments in cooler ambient conditions.
Where is it used?
On segmental viaducts, metro corridors and box-girder bridges during winter and early-morning erection windows where substrate temperatures sit between +10C and +20C.
Why use it?
It cures reliably at low temperatures without the sluggish set of standard-grade adhesives, hardens without shrinkage, and creates a monolithic, watertight joint that transfers shear and post-tensioning loads across segments.
How is it applied?
Mix the pre-batched Part A and Part B (3:1 by weight) to a uniform grey, trowel the paste onto prepared segment faces, then stress the joint before the open time expires.
About Sika Sikadur-31 SBA S-04 IN
Sikadur-31 SBA S-04 IN is the cool-weather grade in Sika’s segmental bridge adhesive family, formulated for the temperature band that trips up general-purpose epoxies. When ambient and substrate temperatures drop to roughly +10C to +20C, ordinary structural adhesives stiffen, extend their working time unpredictably and can fail to develop early strength before the next segment is post-tensioned. This grade is chemically tuned so that erection crews get a predictable pot life, a usable open time and enough early strength to keep a match-cast erection cycle moving even on a cold morning.
The product ships as a pre-batched 6 kg unit, with Part A at 4.50 kg and Part B at 1.50 kg, so the correct 3:1 ratio is fixed at the factory and there is no site guesswork on proportioning. The thixotropic, non-sag consistency lets applicators build a full contact film on vertical and overhead segment faces without the paste slumping out of the joint. Because it is moisture tolerant, it bonds to both dry and damp concrete, which matters on real casting yards and viaduct decks where surfaces are rarely bone dry. The cured joint is impermeable to liquid water and water vapour, so it seals the interface as well as it bonds it.
The technical insight
A segmental joint has two jobs at once: it must lubricate the match-cast faces during closure so the segments seat perfectly, and then it must cure into a rigid, load-transferring film before the tendons are stressed. Temperature governs both. Epoxy cure is an exothermic reaction whose rate roughly halves for every 10C drop, so a standard adhesive that behaves well at +30C becomes slow and under-strength at +12C. The S-04 grade uses a hardener system balanced for the +10C to +20C window: it keeps pot life around 20 minutes and open time around 60 minutes per 100 g at +20C, giving crews room to close the joint, yet it still reaches roughly 60 N/mm2 compressive strength within 24 hours at +10C. The high instantaneous modulus of elasticity, around 11,000 N/mm2, means the hardened film is stiff enough to distribute compressive and shear stresses across the full segment face rather than concentrating them at high spots, while the thixotropy holds a uniform bond-line thickness against gravity until gel.
Where it is used
- Winter and early-morning erection of precast segments on metro and elevated-corridor viaducts
- Match-cast jointing of post-tensioned box-girder bridge segments in cooler regions
- Highway and flyover deck segment bonding where substrate temperatures fall to +10C to +20C
- Sealing the interface between segments to create a watertight, load-transferring joint
- Segment-by-segment cantilever and span-by-span erection during cold-weather programmes
- Bonding vertical and overhead match-cast faces where a non-sag paste is essential
- Structural bonding of hardened concrete to hardened concrete across precast segmental works
- Cool-weather site work where a standard-set segmental adhesive would cure too slowly
Key advantages
- Cures dependably at low temperatures (+10C to +20C) where standard-grade adhesives set too slowly
- Pre-batched 6 kg unit fixes the 3:1 ratio, removing on-site proportioning error
- Thixotropic, non-sag paste stays put on vertical and overhead segment faces
- Moisture tolerant – bonds to both dry and damp concrete surfaces
- Hardens without shrinkage, keeping the bond line dimensionally stable
- Watertight and impermeable to liquid water and water vapour once cured
- High early compressive strength (about 60 N/mm2 at 24h/+10C) supports a tight erection cycle
- Satisfies FIP, BS and ASTM requirements for segmental bridge adhesives
Limitations & considerations
- Application is tied to the +10C to +20C band – warmer sites need the appropriate higher-temperature S-grade instead
- Pot life is short (about 20 minutes per 100 g at +20C), so only mix what can be placed within the working window
- Surfaces must be sound, clean and free of standing water; loose laitance and free water will compromise the bond
- Not a gap-filling grout or a general repair mortar – it is a structural jointing adhesive
- Full design strength develops over 7 days, so post-tensioning and load application must follow the specified schedule
- Cure rate remains temperature-dependent; unexpected drops below the rated band will further slow strength gain
Selection & best practice
Confirm that both substrate and ambient temperatures sit within the +10C to +20C rating before opening a pack – if the site is warmer, switch to the correct higher-temperature grade rather than forcing this one. Prepare the match-cast faces so they are sound, clean and free of laitance, dust and standing water; damp concrete is acceptable but pooled water is not. Combine the full pre-batched Part A and Part B and mix mechanically to a uniform, streak-free grey – never split the pack or adjust the ratio. Trowel an even film onto both mating faces, then bring the segments together and apply the temporary post-tensioning to close the joint while the material is still within its open time. Protect the fresh joint from rain and follow the technical data sheet for temperature-adjusted curing before final stressing and load transfer.
Specifications
| Product type | Two-component, solvent-free thixotropic epoxy adhesive |
| Application | Segmental bridge adhesive, cool-weather grade |
| Rated temperature range | Approx. +10C to +20C (substrate and ambient) |
| Mixing ratio | Part A : Part B = 3:1 by weight |
| Density | Approx. 1.8 kg/L |
| Pot life | About 20 minutes per 100 g at +20C |
| Open time | About 60 minutes per 100 g at +20C |
| Compressive strength | Approx. 60 N/mm2 (24h/+10C); at least 75 N/mm2 (7 days) |
| Modulus of elasticity | Approx. 11,000 N/mm2 (instantaneous) |
| Pack size | 6 kg pre-batched unit (Part A 4.50 kg + Part B 1.50 kg) |
| Standards | Satisfies FIP, BS and ASTM requirements |
Industry use cases
Metro & Elevated Corridors
Keeps precast segment erection on viaducts moving during winter and cold early-morning shifts when standard adhesives would cure too slowly to hold the cycle.
Highway & Flyover Bridges
Bonds match-cast box-girder segments into watertight, load-transferring joints on deck programmes running through cooler months.
Precast Yards & Launching
Delivers a predictable pot life and open time so span-by-span and cantilever erection crews can close and stress joints on schedule at +10C to +20C.
Infrastructure Consultants
Provides an FIP/BS/ASTM-compliant, temperature-matched adhesive grade that can be specified with confidence for cool-weather segmental works.
Frequently asked questions
What temperature range is the S-04 grade meant for?
What is the mixing ratio and does the pack fix it?
How much working time do I get?
Can it be applied to damp concrete?
When can the joint be post-tensioned?
Does it meet bridge specifications?
How we position Sika Sikadur-31 SBA S-04 IN
Choose the S-04 grade only when your site sits in the +10C to +20C band; for warmer erection conditions, move up to the matching higher-temperature grades in the same Sikadur-31 SBA IN family so pot life and cure stay on spec. Where the specification is written around Sika structural bonding, keep it within the range and pair it with Sika’s epoxy repair and anchoring systems. Space Arc also stocks equivalent segmental and structural bonding lines from Fosroc and other brands, so consultants can match the adhesive to the project spec and the temperature grade rather than the label.
Fosroc Nitobond SBA — A specifier standardised on Fosroc, or working to a Fosroc-based project specification, may prefer Nitobond SBA as the directly equivalent two-component epoxy segmental bridge adhesive, selecting the Fosroc temperature grade that matches the site conditions.
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