About Sika Intraplast NN

Sika Intraplast NN is one of those quietly useful products that many site engineers reach for without thinking twice. It is not a grout in itself; it is an admixture in powder form that you blend into a neat cement slurry or a cement-sand grout mixed from materials already on the project. Once added, it does two jobs at once. It improves the fluidity and cohesion of the grout so the mix flows into tight ducts and narrow gaps without segregating, and it generates a controlled expansion while the grout is still fresh so the hardened mass presses against the surrounding surfaces rather than pulling away from them. The result is a dense, non-shrink grout that maintains full contact and bond, produced at a fraction of the cost of a factory-bagged equivalent.

For Indian contractors this economy is the main attraction. On large works such as bridges, prestressed structures, tunnels and anchoring jobs, the volumes involved can be considerable, and being able to grout with project cement and clean sand keeps material budgets sensible. Just as important for post-tensioning and anchoring work, Intraplast NN is chloride-free, so it will not corrode reinforcement or prestressing cables the way older calcium-chloride accelerators could. It is supplied as a fine powder in a 12.5 kg bag, stores easily, and is dosed by weight of cement, which makes it straightforward to fold into an existing batching routine on site.

The technical insight

The behaviour that makes Intraplast NN worth using comes down to timing. A plain cement grout shrinks as it hydrates and bleeds, which leaves gaps between the grout and the duct wall, the anchor, or the base plate exactly where you wanted a solid, load-transferring contact. Intraplast NN counters this by producing a small, controlled gaseous expansion in the wet, plastic state, before the grout takes its initial set. That gentle rise pushes the still-fluid grout outward into full contact with every surface it touches, and because it happens while the material can still move, it compensates for the shrinkage and settlement that would otherwise open up voids. Alongside the expanding action, the fluidifying and water-reducing components let you achieve a pumpable, cohesive consistency at a lower water content, which is what actually delivers the density, bond and strength once the grout hardens. The practical consequence is that the window matters: the expansion is a wet-state effect, so batches should be sized and placed so grouting finishes while that reaction is still working. Overdosing does not help, which is why the correct dose is always settled by trial mix against the specific cement and water-cement ratio in use.

Where it is used

• Grouting of prestressed and post-tensioned cable ducts, where chloride-free chemistry protects the strand
• Rock, soil and cable anchor grouting requiring full-contact bond along the fixed length
• Bedding of machine base plates, bearing plates and structural steel foundations
• Grouting of pre-placed aggregate concrete for mass pours and repairs
• Filling voids, cavities and gaps behind linings and retaining structures
• Tunnel-lining and annular-space grouting where a cohesive, non-segregating mix is needed
• Pressure and injection grouting into confined or hard-to-reach zones
• Producing an economical non-shrink grout from site cement and sand for general fixing work

Key advantages

• Chloride-free, so it is safe to use around reinforcement and prestressing cables
• Develops non-shrink property through controlled wet-state expansion for full contact and bond
• Improves flow and pumpability so grout reaches tight ducts and narrow gaps
• Increases cohesion, reducing bleeding and segregation in the mix
• Water-reducing action helps achieve a denser, stronger hardened grout
• Lets you build grout from project cement and sand, cutting material cost on large volumes
• Simple powder dosing by weight of cement fits straight into site batching
• Compact 12.5 kg bag is easy to store, transport and proportion

Limitations & considerations

• It is an admixture, not a grout on its own; final performance still depends on the cement, sand and water-cement ratio you use
• Expansion is a fresh-state effect, so placement must be finished before initial set or the benefit is lost
• The correct dose must be found by trial mix; it varies with cement type, temperature and w/c ratio
• Not a high-strength, non-shrink precision grout for heavily loaded machine bases; a pre-bagged system is better where certified strength and expansion are specified
• Over-dosing does not increase benefit and can work against grout density and strength
• Results depend on good site mixing discipline and clean, well-graded sand where sand is added

Selection & best practice

Specifications

Industry use cases

How we position Sika Intraplast NN

Sika Intraplast NN sits in the economy end of the grouting family: it turns site cement into a workable non-shrink grout rather than being a grout itself. Within the Sika range, contractors who want a ready-mixed cementitious grout usually move to Sika’s pre-bagged non-shrink grouts, while duct-grouting on prestressing works often pairs it with Sika’s dedicated PT grout systems. Across our other brands, where a project specifies a certified free-flow, high-strength precision grout, for example under heavily loaded machine bases or crane rails, a factory-bagged product is the right call. In that situation the closest equivalent we stock is Fosroc Conbextra GP2, which gives you documented flow and 28-day strength straight from the bag. We also supply complementary chloride-free admixtures and repair mortars, so we can match Intraplast NN to the surrounding scope, whether that is anchoring, concrete repair or waterproofing.

Related Concrete Admixtures products

View all Concrete Admixtures products →