About Sika SikaCem-135 Intraplast

SikaCem-135 Intraplast is Sika’s ready-to-mix expanding grout admixture, supplied as a brown free-flowing powder that a specialist crew blends into a site-batched cement grout. Its job is narrow but important: take an ordinary Portland cement slurry and give it the three properties a duct or anchor grout must have, namely good fluidity for clean pumping, cohesion so it does not segregate or bleed, and a controlled wet-state expansion that keeps the hardened grout in firm contact with the strand, duct wall or rock face. Because the product conforms to the MORTH 5th Revision Appendix 1800/III mix design, it sits comfortably inside the specifications that Indian bridge and highway consultants already write for post-tensioning work.

What sets this grade apart is what it leaves out. Many older expanding grout admixtures rely on aluminium powder, which reacts with the alkaline grout to release hydrogen gas and drive expansion. SikaCem-135 Intraplast is aluminium-free and produces no hydrogen at all; it expands by entraining fine micro-bubbles instead. It also carries no chlorides or other corrosive ingredients, so it is safe against the high-tensile steel it surrounds. For engineers grouting sealed tendon ducts, that combination, no free hydrogen and no chloride, removes two of the classic durability worries in one product. It is stable in hot and tropical conditions, which matches most of the Indian site calendar.

The technical insight

The mechanism rests on two agents working together. A dispersing (plasticising) fraction coats the cement particles and reduces the water they need to flow, so the grout stays pumpable at a low water-cement ratio, around 0.39 in Sika’s reference mix, which is what gives the hardened grout its strength and low permeability. The second fraction is the expanding agent. Rather than generating gas, it introduces and stabilises a fine population of micro-bubbles that make the fresh grout grow slightly in volume, about 2.1% at three hours by ASTM C940, before it sets. Because expansion happens while the grout is still plastic and is restrained inside a closed duct or under a bearing plate, that growth translates into positive contact pressure against every surface instead of a loose, low-strength fill. The admixture is also initially retarding, delaying initial set to roughly 5.75 hours, which keeps the grout workable long enough for long tendon runs and suppresses bleeding to about 0.25%. The net result is a dense, void-free, non-shrink grout that bonds the tendon to the structure.

Where it is used

• Grouting of post-tensioned prestressing cable ducts and tendon sheaths
• Anchor and holding-down bolt grouting where tight filling and bond are needed
• Rock anchor and soil anchor grouting in tunnelling and slope stabilisation
• Injection of cracks and cavities in concrete and masonry
• Bedding of bearing plates and machine base plates
• Consolidation grouting of soil, fissured rock and loose concrete
• Filling of pre-placed aggregate (prepacked) concrete
• Grouting joints and voids in precast concrete elements and tunnel linings

Key advantages

• Aluminium-free and generates no hydrogen gas, so no gas voids form inside sealed ducts
• Chloride-free and non-corrosive, protecting high-tensile prestressing strand
• Wet-state expansion gives a genuine non-shrink grout with firm interface contact
• Good compressive and bond strengths (28 N/mm2 at 7 days, 39 N/mm2 at 28 days)
• Improved fluidity and cohesion for clean pumping without segregation or bleeding
• Initially retarding, which reduces bleeding and extends the working window
• Reduces gauging water, improving strength and durability of the set grout
• Conforms to MORTH 5th Revision Appendix 1800/III, easing consultant approval

Limitations & considerations

• It is an admixture, not a ready-mixed grout; you must batch OPC (53 grade) and water on site and control the mix yourself
• Not a non-shrink admixture for conventionally placed structural concrete; it is designed for injection and grouting only
• Expansion must be restrained by a duct, form or plate; unformed exposed placements give substantially lower physical properties
• The grout must be used within about 30 minutes to capture the full expansion, so batch sizes have to be limited
• Different cements expand differently, so field trials are needed to fix the exact dosage and confirm strength, flow and bleed
• Do not add sand when the product is used in prestressing work

Selection & best practice

Specifications

Industry use cases

How we position Sika SikaCem-135 Intraplast

SikaCem-135 Intraplast is the right pick when your specification points to an aluminium-free, hydrogen-free duct grout, especially on post-tensioned bridge work under MORTH. If you instead need a ready-mixed, poured non-shrink grout for base plates and pockets rather than an admixture you batch yourself, look at Sika’s SikaGrout range from the same family. For heavier structural or machine-base grouting we also stock Fosroc Conbextra and MC-Bauchemie Emcekrete cementitious grouts, and for two-part epoxy anchoring of bolts and dowels our Sika AnchorFix and Fosroc Lokfix chemical anchors are the usual companions. Tell us the duct diameter, tendon length and site temperature and Space Arc will confirm the dosage, mixing gear and companion products for your job.

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