Conbextra AT
Anti-Bleed Non-Shrink Cementitious Grout for Wet and Submerged Grouting
Authorized Project Distributor — Fosroc India | Space Arc Engineering, Ghaziabad
Product Overview
Conbextra AT is an anti-bleed, non-shrink, single-component cementitious grout from Fosroc designed for grouting in wet conditions, in the presence of flowing water, and for applications where zero bleed (zero water separation) is a critical performance requirement. Standard cementitious grouts exhibit some degree of bleed — separation of free mixing water from the cement particles before the grout stiffens — particularly at higher water-cement ratios and in warm conditions. Bleed water rising to the surface of the grout, or accumulating at the top of a grouted void, creates voids and weak zones in the hardened grout that reduce structural performance and create pathways for water and corrosive agents. In applications where the grout is placed in contact with water (such as underwater grouting of pile caps, foundation underpinning in flooded excavations, or grouting of tendon ducts in post-tensioned concrete), the bleed problem is compounded by washout — the water surrounding the grout washes out the fresh cement paste before it can set. Conbextra AT is specifically formulated with anti-bleed and anti-washout technology: the admixture package modifies the rheology of the fresh grout to prevent water separation under normal conditions and to resist dilution and washout when placed in contact with standing or flowing water. The product is used for underwater grouting of anchor bolts and structural connections, for post-tensioning tendon duct grouting where zero bleed is required, and for grouting in wet concrete or wet rock in civil engineering applications. Space Arc Engineering distributes Conbextra AT for bridge, tunnelling, and infrastructure wet-condition grouting projects across Delhi NCR and Northern India.
Applications
- Anti-bleed tendon duct grouting in post-tensioned concrete structures
- Underwater anchor bolt and connection grouting in flooded excavations
- Wet condition pile cap and foundation grouting
- Marine and coastal structure grouting in tidal and splash zones
- Rock bolt grouting in water-bearing rock in tunnels and underground works
- Foundation underpinning grouting in wet or water-bearing ground
Key Advantages
- Anti-bleed — zero water separation even in wet and submerged conditions
- Anti-washout — resists dilution when placed in contact with water
- Non-shrink for void-free grouting without settlement
- Factory-blended single-component — just add water on site
- Suitable for both free-flow grouting and pumped injection
- Meets requirements for tendon duct grouting (zero bleed specification)
Technical Data
| Type | Anti-bleed non-shrink cementitious grout |
| Bleed | Zero (at specified w/c ratio) |
| Washout Resistance | High (specific anti-washout formulation) |
| Consistency | Fluid (free-flow for normal application) |
| Compressive Strength (28 day) | Greater than 30 MPa (typical) |
| Packaging | 25 kg bags |
Get a Quote
📞 +91 9999155255
📧 info@space-arc.com
🏢 Space Arc Engineering, Sahibabad, Ghaziabad
Frequently Asked Questions
What is the difference between Conbextra AT and Conbextra EN for tendon duct grouting?
Both Conbextra AT and Cebex EN are designed for zero-bleed grouting applications. Cebex EN is a specialised admixture added to a separately prepared cementitious grout base, providing expansion and zero bleed at the very low water-cement ratio (0.40 to 0.44) needed for optimum tendon duct grout performance. Conbextra AT is a complete pre-blended grout product with anti-bleed and anti-washout properties built into the formulation — it is particularly suited to applications in wet or submerged conditions where washout resistance (not just zero bleed) is needed. For standard dry-environment tendon duct grouting, Cebex EN in a low water-cement ratio grout is preferred. For grouting in wet or water-present conditions (flooded ducts, marine structures, underwater anchors), Conbextra AT provides the additional washout resistance needed.
How is Conbextra AT applied in an underwater or flooded environment?
For underwater grouting with Conbextra AT, the grout is mixed on the surface at the specified water-cement ratio and pumped through a tube or tremie pipe to the base of the void or connection being grouted. The grout is introduced from the bottom, displacing the water upward and out through a vent at the top. This bottom-up tremie placement technique is essential — placing grout from the top into water causes mixing and dilution of the grout (even for anti-washout products) and should never be done. The pumping rate must be sufficient to maintain a continuous upward flow front without pausing, as pauses allow the water-grout interface to stabilise and can lead to weak layers. The vent at the top should be observed until clean, uniform grout (not water) flows out, confirming the void is fully filled.
Can Conbextra AT be used in post-tensioned tendon duct grouting as a substitute for standard duct grout with Cebex EN?
Conbextra AT can be used for post-tensioned tendon duct grouting and provides zero-bleed performance. However, for the most critical applications (major bridge post-tensioning where the current international standards for duct grouting apply — such as fib Bulletin 20 or PTI DC10.5-12), the specific grout specification may require zero-bleed testing by the ASTM C940 anti-bleed test method at the specified water-cement ratio, and the grout must meet performance criteria for viscosity, setting time, and strength at that water-cement ratio. Consult the post-tensioning specialist, the structural engineer, and the bridge authority for the applicable grouting specification before selecting the grout product. Space Arc Engineering can provide technical support in selecting the correct Fosroc grout product for the specific post-tensioning specification.
Source Conbextra AT for Your Project
Space Arc Engineering is an Authorized Project Distributor for Fosroc India serving Delhi NCR, Ghaziabad, Noida and Uttar Pradesh.
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