About Fosroc Conbextra GR

Fosroc Conbextra GR is a flowable, non-shrink cementitious grout from the well-known Conbextra range, formulated for the precision grouting of gaps and the anchoring of fixings. It is supplied as a factory-blended dry powder of Portland cement, selected graded aggregates and chemical additives; the additives impart a controlled expansion in the plastic state while keeping water demand low, so the hardened grout neither bleeds nor segregates. On site the contractor simply adds a measured quantity of clean water and mixes to the required consistency, which removes the batching variability and quality risk associated with sand-cement grouts mixed from loose materials. The product is designed for a generous gap-thickness window of 6 to 100 mm, which makes it versatile enough to handle thin bedding layers as well as deeper baseplate and pocket fills without the contractor needing to switch products. Because the ingredients are non-corrosive and chloride-free, Conbextra GR protects the steel anchors, baseplates and reinforcement it surrounds, an important consideration for plant and equipment expected to remain in service for decades. It develops good early strength, allowing formwork to be struck and equipment to be returned to service relatively quickly, which is valuable on time-critical industrial and infrastructure projects across India where access windows and shutdown durations are tightly controlled. As an authorised Fosroc distributor serving Delhi NCR and the wider Pan-India market, Space Arc Engineering supplies Conbextra GR alongside the full Conbextra grouting family and provides specification and site-application support to ensure the right grade is matched to each grouting situation.

The technical insight

The defining behaviour of a precision grout is what happens during the plastic and early-hardening phase. Ordinary cement grout shrinks as it sets and bleeds water to the surface, leaving voids and a weak laitance layer exactly where full bearing contact is needed under a baseplate. Conbextra GR addresses this with a shrinkage-compensating system that produces a slight positive expansion while the grout is still plastic, so the grout stays in intimate contact with the substrate and the underside of the plate as it gains strength. The low water demand of the blend is equally important: a high water-to-powder ratio would flow easily but would also bleed, segregate and lose strength, so the formulation is balanced to remain flowable and cohesive at a controlled water content. The result is a homogeneous, dense matrix with effective load transfer across the full bearing area. In practice the achievable performance is sensitive to the water added — over-watering to make pouring easier is the single most common cause of bleed and reduced strength on site. Because published compressive-strength figures, flow values and standard classifications vary by region and pack, the governing values for any project should be read from the current Fosroc Conbextra GR Technical Data Sheet for the supply country rather than assumed from a related grade such as Conbextra GP or GP2.

Where it is used

• Bedding grout beneath the baseplates of pumps, motors, compressors and rotating equipment
• Grouting under structural steel columns, stanchion baseplates and crane-rail soleplates
• Anchoring holding-down bolts, dowels and starter bars into pre-formed pockets and drilled sockets
• Filling cavities, recesses, gaps and voids between 6 and 100 mm in concrete and masonry
• Bedding of precast concrete units, bearing plates and bridge components
• General non-shrink grouting where chloride-free, non-corrosive contact with embedded steel is required

Key advantages

• Non-bleeding and non-segregating, giving a uniform grout and consistent bearing contact
• Shrinkage-compensated to maintain full effective contact under baseplates and in pockets
• Wide gap-thickness capability from 6 to 100 mm in a single product
• Chloride-free and non-corrosive — safeguards anchors, baseplates and reinforcement
• Good early strength for faster formwork striking and quicker return to service
• Suitable for both internal and external applications
• Factory-blended single-component powder — only clean water is added on site, reducing batching error
• Free-flowing consistency that fills confined and irregular gaps by pour or pump

Limitations & considerations

• Final strength, flow and standard classification depend on the correct water content — over-watering causes bleed, segregation and strength loss
• Gap thickness must stay within the 6 to 100 mm range; very thin or very deep sections need a different grade or aggregate extension per Fosroc guidance
• As a cementitious grout it has limited chemical resistance; aggressive acid, solvent or high-temperature exposure calls for an epoxy grout such as Conbextra EP
• Requires a clean, sound, pre-soaked (saturated surface-dry) substrate and properly sealed formwork to flow and bond correctly
• Not formulated for continuous underwater placement — use a dedicated underwater grade such as Conbextra UW
• Low-temperature curing slows strength gain; hot, windy conditions accelerate stiffening and shorten working time
• Exact verified specifications must be taken from the current country-specific Technical Data Sheet before specification

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Conbextra GR

Conbextra GR sits in the cementitious end of Fosroc’s Conbextra grouting range as a flowable, general-purpose non-shrink grout for the 6 to 100 mm gap window. Within the Fosroc family it is closely related to Conbextra GP, GP1, GP2, GP2N and GP3 — buyers choosing on strength class, flow or gap thickness should compare against these grades, while Conbextra HF suits very high flow over longer paths, Conbextra UW is the choice for underwater placement, and Conbextra EP (epoxy) is specified where chemical resistance or heavy dynamic loading governs. Against competitor products, Conbextra GR competes most directly with Sika’s SikaGrout range, MYK/MBS and BASF/Master Builders Solutions MasterFlow non-shrink grouts, Dr. Fixit (Pidilite) grouting compounds and STP grouts, as well as UltraTech Powergrout in the Indian market. Honestly, for many routine baseplate and anchor-grouting tasks several of these brands are technically comparable on the headline non-shrink, chloride-free properties; Fosroc’s edge is the breadth and maturity of the Conbextra system, wide site familiarity among Indian contractors and engineers, and consistent factory blending. The decisive factors in practice are matching the verified strength and flow figures on the current datasheet to the specification, confirming availability and pricing locally, and the technical and application support behind the supply — which, for Delhi NCR and Pan-India projects, Space Arc Engineering provides as an authorised Fosroc distributor.

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