About Fosroc Cebex 100

Fosroc Cebex 100 is a powder admixture used to upgrade cementitious grouts that are batched on site, rather than a pre-packaged finished grout. Each dose combines two active functions: a plasticising agent that improves the flow and workability of the cement-sand grout, and a gas-producing expansion medium that generates controlled positive expansion as the grout sets. This controlled gassing action delivers unrestrained expansion of up to around 4%, compensating for the plastic settlement and shrinkage that would otherwise leave voids and loss of contact under base plates, in ducts and within filled cavities. Because the system is designed around site-batched grout, Cebex 100 lets contractors produce a non-shrink, free-flowing grout from locally available cement and clean graded sand, which is valuable on Indian infrastructure and building sites where ready-mixed bagged grouts are not always practical to transport or store. It is important to understand what Cebex 100 is not: it is not a liquid, and it is not a polycarboxylate-ether (PCE) or sulphonated-naphthalene (SNF) high-range superplasticiser of the type dosed by percentage of cement weight. Its dose is unit-based, and its defining contribution is the expansion behaviour, not high-range water reduction. The product contains no chloride (Nil to BS 5075) and contains no iron, so it does not carry the staining and corrosion concerns associated with metallic-aggregate expansion systems. For finished, pre-bagged non-shrink grouts used to fill larger gaps in a single product, the Fosroc Conbextra range is the relevant family; Cebex 100 instead sits upstream as the admixture that gives a job-mixed grout its non-shrink and flow characteristics. Space Arc Engineering supplies Cebex 100 as an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India, and can advise on selecting between an admixture-based site grout and a ready-mixed Conbextra grout for a given application.

The technical insight

The performance of Cebex 100 comes from a timed gas-producing reaction within the fresh grout. After mixing, the gas-producing medium generates a controlled volume of gas that produces unrestrained (positive) expansion of up to approximately 4%, with the expansion typically developing over a window of about 15 minutes to 2 hours. This timing matters in practice: the expansion must occur while the grout is still plastic so it can take up the settlement and bleed that naturally occur, then the grout sets in firm, gap-filling contact. The plasticising agent works alongside this to keep the grout fluid at a controlled water content, which is what allows it to flow into thin bed-grouting gaps and along tendon ducts. Expansion is measured to ASTM C827. The grout system is referenced for prestressing grout use under BS 8110 Part 1:1997 Annex A, and the chloride content is Nil to BS 5075 — both relevant where reinforcement and prestressing strand must be protected from chloride-induced corrosion. In hot Indian site conditions, remember that high ambient temperatures accelerate both the gassing reaction and the stiffening of the grout, so mixing quantities, water temperature and placing time should be planned so the grout is placed well within its working window; trial mixes at site temperature are recommended before production grouting.

Where it is used

• Improving site-batched cement-sand grouts for bed grouting beneath equipment and structural elements
• Duct grouting of post-tensioning tendon ducts where a non-shrink, flowable cementitious grout is required
• Non-shrink infilling of gaps, pockets and cavities using job-mixed cementitious grout
• Jointing applications where a site-mixed grout must stay in firm contact without settlement
• Producing free-flowing grout from locally available cement and graded sand on remote infrastructure sites

Key advantages

• Combines plasticising action with controlled gas expansion in a single powder admixture
• Provides unrestrained expansion of up to around 4% to compensate for plastic settlement and shrinkage
• Contains no chloride (Nil to BS 5075), protecting embedded steel and prestressing strand
• Contains no iron, avoiding the staining and corrosion risks of metallic expansion systems
• Simple unit-based dosing (one 227 g unit per 50 kg cement) for consistent batching on site
• Lets contractors produce non-shrink grout from locally sourced cement and sand, reducing dependence on bagged ready-mix

Limitations & considerations

• It is an admixture, not a finished grout — the contractor must still batch a correctly proportioned cement-sand grout on site
• Performance depends on accurate dosing and good mixing discipline; under- or over-dosing changes the expansion behaviour
• Expansion is positive and unrestrained, so it suits plastic-state settlement compensation rather than acting as a high-strength structural grout on its own
• The gassing reaction and grout stiffening accelerate in hot weather, narrowing the placing window
• For filling large gaps or where a single pre-bagged product is preferred, a ready-mixed grout such as Fosroc Conbextra is more appropriate

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Cebex 100

Positioned as the Fosroc-authorised choice for contractors who batch their own cementitious grouts on site and need controlled, chloride-free expansion — distinct from the ready-mixed Conbextra grout range, with Space Arc Engineering providing supply and application support across Delhi NCR and Pan-India.

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