Fosroc Cebex FCC422
A single-pack powder additive that turns ordinary cement and sand into a cohesive, non-shrink, controlled-expansion grout for bedding, void filling and precast jointing.
What is it?
Fosroc Cebex FCC422 is a powder grout additive that combines a plasticising agent with a gas-producing expansive medium and graded fillers. Added to site-batched OPC and sand, it produces a cohesive, low-water/cement, non-shrink grout that develops a controlled positive expansion before initial set.
Where is it used?
Used across India for machine-base and structural bed grouting, non-shrink infilling and jointing, joint filling between precast concrete units, grouting voids in structural members, pipe-joint grouting, and general repair work where settlement and shrinkage must be avoided.
Why use it?
It lets a contractor make a reliable non-shrink grout on site from locally available cement and sand at a fraction of the cost of a bagged pre-mix, while guaranteeing full contact with bearing surfaces, low permeability and around 40 N/mm² compressive strength at 28 days.
How is it applied?
Dry-blend 5 kg of Cebex FCC422 with one 50 kg bag of fresh OPC and 50 kg of zone-3 sand, then mix with measured water at a w/c ratio of 0.40-0.44 using a free-fall mixer or paddle drill. Pour into pre-wetted, cleaned voids and cure with water ponding or wet hessian.
About Fosroc Cebex FCC422
Fosroc Cebex FCC422 is a “plasticised expanding grout additive” — a dry powder that a contractor blends with ordinary Portland cement and sand on site to create a non-shrink cementitious grout. It belongs to Fosroc’s long-running Cebex family of grout admixtures, sitting alongside Cebex 100 and Cebex 200, but it is positioned for jobs that need a medium expansion and a genuinely low water/cement ratio rather than a high-fluidity injection grout.
The product works on two fronts at once. First, the plasticising fraction disperses the cement particles so the grout flows and remains cohesive at a reduced water/cement ratio (0.40 to 0.44), which is the single biggest lever for low permeability and durable, high strength. Second, a gas-producing expansive medium generates gas during early hydration, before the grout takes its initial set. That controlled expansion counteracts the natural plastic settlement and drying shrinkage of a cement grout, so the hardened grout retains its original volume and presses tightly against the bearing surfaces it was poured around — eliminating the voids and slack contact that plague hand-mixed sand-cement grouts. Graded fillers in the powder keep the mix uniform and aid stability.
For a distributor’s customer in India, the practical appeal is economic as well as technical: instead of buying a heavy bagged pre-bagged non-shrink grout, the contractor supplies the bulk cement and sand and adds one 5 kg pack of FCC422 per cement bag. This keeps freight and material cost down on high-volume bedding and backfilling work while still delivering the non-shrink, cohesive performance a consultant will specify. It is supplied by Fosroc Chemicals (India) and stocked and applied by Space Arc Engineering across Delhi NCR and Pan-India.
The technical insight
The defining behaviour of Cebex FCC422 is gaseous expansion that is timed and quantified, not the bulk metallic expansion of older iron-filing systems. The gas is released during early hydration and ahead of initial set, so the expansion happens while the grout is still plastic and able to redistribute — it pushes the grout into intimate contact with bearing surfaces without building up the excess internal pressure that could crack a confined pour. Because there is no metallic iron in the system, there is no risk of later rust-staining or corrosion-driven disruption in the hardened grout, which matters for exposed machine bases and structural repairs.
The second, quieter mechanism is the water reduction. By plasticising the mix, FCC422 lets the grout flow and stay cohesive at a w/c of 0.40-0.44 instead of the 0.50-plus that a plain sand-cement grout often needs to be workable. Lower free water means a denser matrix, lower permeability and a measured strength climb to about 40 N/mm² at 28 days on 70.6 mm cubes (10 / 20 / 32 / 40 N/mm² at 1 / 3 / 7 / 28 days) when good fresh OPC is used and the cubes are cured under restraint. The headline number is therefore conditional: it is delivered by the combination of correct dosage, fresh cement, accurate water measurement and proper restrained curing — not by the additive alone.
Where it is used
- Bed grouting beneath machine bases, base plates and structural members
- Non-shrink infilling and jointing where settlement must be avoided
- Joint filling between precast concrete units
- Grouting of voids in structural members
- Grouting of pipe joints
- General concrete repair work where shrinkage of the cement grout must be controlled
- High-volume foundation and pocket grouting where bulk cement/sand economics matter
Key advantages
- Non-shrink: controlled positive expansion before initial set retains the grout’s original volume
- Develops high compressive strength of around 40 N/mm² at 28 days with good OPC
- Low water/cement ratio (0.40-0.44) gives low permeability and long-term durability
- Produces a cohesive, easy-flowing grout that places without segregation
- Ensures complete contact with bearing surfaces, eliminating voids under base plates
- Iron-free system, so no rust-staining or corrosion-related expansion in service
- Economical on site: one 5 kg pack treats a full 50 kg cement bag using locally sourced sand
- Compatible with all types of ordinary Portland cement
Limitations & considerations
- Not compatible with high alumina cement — use only with ordinary Portland cement
- Delivers a medium expansion only; for high-fluidity duct/cable injection grouts a different Cebex grade is more suitable
- It is an additive, not a complete pre-bagged grout — final strength and non-shrink performance depend on fresh OPC, correct sand grading (zone 3), accurate water and proper mixing
- Short shelf life of 6 months in dry storage; high temperature and humidity shorten this
- Requires diligent curing — water ponding or wet hessian for a minimum of 15 days to reach quoted strengths
- Alkaline powder: requires gloves and eye protection during handling
- Quoted strength data assumes cubes cured under restraint with good OPC; site results vary with materials and workmanship
Selection & best practice
Always dry-blend cement, zone-3 sand (1:1 by weight) and Cebex FCC422 thoroughly before adding water, then mix in accurately measured water at a w/c of 0.40-0.44. Use fresh OPC and mechanical mixing — a free-fall mixer for 50 kg cement and above, or a slow-speed paddle drill for smaller batches. Clean and pre-wet the substrate for at least 24 hours, removing all standing water before the pour, keep the unrestrained surface area to a minimum, and place promptly to capture the full expansion. Cure exposed surfaces by water ponding or wet hessian for a minimum of 15 days (or use Concure WB membrane curing compound). Never use FCC422 with high alumina cement, and confirm stock is within its 6-month shelf life.
Specifications
| Product type | Plasticised expanding grout additive (powder) |
| Base / system | Plasticising agent + gas-producing expansive medium with graded fillers |
| Form | Powder additive |
| Dosage | 5 kg per 50 kg bag of OPC (10% by weight of cement) |
| Water/cement ratio | 0.40 to 0.44 (0.42 typical) |
| Typical mix | OPC : sand (zone 3) = 50 kg : 50 kg, 1:1 by weight |
| Compressive strength (1 day) | 10 N/mm² |
| Compressive strength (3 days) | 20 N/mm² |
| Compressive strength (7 days) | 32 N/mm² |
| Compressive strength (28 days) | 40 N/mm² (with good OPC) |
| Test cube size | 70.6 mm x 70.6 mm x 70.6 mm, cured under restraint |
| Cement compatibility | All ordinary Portland cements; NOT high alumina cement |
| Curing | Water ponding or wet hessian, minimum 15 days (Concure WB also suitable) |
| Packaging | 5 kg bags |
| Shelf life | 6 months in dry store in original packing |
| Health & safety | Alkaline; wear gloves, wash splashes with clean water |
| Datasheet reference | Fosroc India INDIA/2010/0306/E |
Industry use cases
Industrial / plant engineering
Bed grouting beneath machinery base plates and structural columns, where non-shrink behaviour and complete contact with the bearing surface are essential to transfer load without voids.
Precast concrete construction
Filling joints between precast units and grouting pockets, using a cohesive grout that will not settle or shrink away from the connection.
Civil / structural repair
Grouting voids inside structural members and general repair work where shrinkage of a plain cement grout would leave gaps.
Water and pipeline works
Grouting of pipe joints where a stable, non-shrink, low-permeability seal is required.
Infrastructure & foundations
High-volume non-shrink infilling and foundation pocket grouting where site economics favour adding FCC422 to bulk cement and sand rather than importing bagged pre-mix.
Frequently asked questions
Is Fosroc Cebex FCC422 a real product?
What is the correct dosage of Cebex FCC422?
What compressive strength does it achieve?
Can I use Cebex FCC422 with any cement?
How should grout made with FCC422 be cured?
How is it packed and how long does it last?
How we position Fosroc Cebex FCC422
Cebex FCC422 is the workhorse of the Cebex grout-admixture family and should be chosen when the priority is a low water/cement, medium-expansion, non-shrink grout made economically from site cement and sand — typical of bed grouting, precast jointing and void filling. Where the job instead calls for a high-fluidity, pumpable grout for ducts and cables, Fosroc Cebex 100 (up to ~4% expansion, BS 8110 compliant, iron- and chloride-free) or the hydrogen-free Cebex 200 (~2% expansion) are the better-fitted siblings; for fully bagged, ready-to-use non-shrink grouting at higher strengths, Fosroc’s Conbextra GP2 / GP3 cementitious grouts remove site-batching variability altogether. Compatible curing is provided by Concure WB. Against the wider market, credible alternatives an Indian consultant may also specify include Sika’s grout admixtures and Intraplast/SikaGrout range, BASF/MBS (Master Builders Solutions) MasterFlow and MasterRoc grouts, Dr. Fixit’s grouting additives, and STP (Pidilite) construction-chemical lines. As an authorised Fosroc distributor and applicator, Space Arc Engineering supplies genuine Cebex FCC422 with technical support and on-site guidance across Delhi NCR and Pan-India, and can advise when a ready-mixed Conbextra grout is the safer specification than a site-batched additive.
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