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Fosroc Conbextra GP Grout 20kg

Code: 40-FC501020-20KG
U.O.M. - Each
Conbextra GP Grout is a general purpose shrinkage compensated cementitious grout, supplied as a dry powder. The addition of a controlled amount of clean water produces a flowing shrinkage compensated grout for gap thicknesses from 10 mm up to 100 mm. It is a blend of Portland cement, graded fillers and chemical additives which impart controlled expansion in the plastic state whilst minimising water demand. Low water demand ensures high early strength and graded filler designed to assist uniform mixing and produce a consistent grout.


Conbextra GP is used for general purpose grouting where it is essential to eliminate shrinkage when completely filling voids or grouting between a base plate and substrate, e.g. the grouting of a stanchion base plate. It can also be used for anchoring a wide range of fixings such as masts and anchor bolts.


  • High ultimate strength and low permeability ensure the durability of the hardened grout
  • Gaseous expansion system compensates for shrinkage and settlement in the plastic state
  • Can be dry packed, rammed, trowelled, poured and pumped Pre-packaged material overcomes potential on-site mixing variations
  • Develops high early strength without the use of chlorides
  • No metallic iron content to cause staining
  • Ideal for:

  • Filling voids or grouting between a base plate and substrate
  • Grouting stanchion base plates etc
  • Anchoring a wide range of fixings such as masts and anchor bolts

    Surface Preparation:

    The substrate must be free from oil, grease or any loosely adherent material. Bolt holes or fixing pockets must be blown clean of any dirt or debris. Several hours prior to grouting, the area of cleaned foundation should be flooded with fresh water. Immediately before grouting takes place, any free water should be removed with particular care being taken to blow out all bolt holes and pockets.

    It is essential that the base plate is clean and free from oil, grease or scale. Air pressure relief holes should be provided to allow venting of any isolated high spots.

    Formwork should be constructed to be leakproof. This can be achieved by using foam rubber strip or construction silicone sealant beneath the constructed formwork and between joints. Generally the gap width between the perimeter formwork and the plate edge should not exceed 150 mm on the pouring side and 50 mm on the opposite side. It is advisable where practical to have no gap at the flank sides.


    A forced-action mixer is essential. Larger quantities will require a high shear vane mixer. Do not use a colloidal impeller mixer. To enable the grouting operation to be carried out continuously, it is essential that sufficient mixing capacity and labour are available. The use of a grout holding tank with provision to gently agitate the grout, following correct mixing, may be required.


    Place the grout within 20 minutesof mixing (at 20 degrees) to gain full benefit of the expansion process. Conbextra GP can be placed in thicknesses from 10 mm up to 100 mm in a single pour when used as an underplate grout. Where the grouting gap beneath the base plate exceeds the maximum thickness allowed, then the grout can filled / bulked out with aggregate to minimise exotherm heat build up. Alternatively Conbextra Deep pour is available for pours up to 500 mm thick.

    Continuous grout flow is essential. Pouring should be from one side of the void to eliminate any air or pre-soaking water becoming trapped under the baseplate. The grout head must be maintained at all times so that a continuous grout front is achieved.

    Where large volumes have to be placed Conbextra GP may be pumped.

    On completion of the grouting operation, exposed areas should be thoroughly cured. This should be done by the use of Concure curing membrane, continuous application of water and/or wet hessian.

    Clean Up:

    Remove from tools and equipment with clean water immediately after use. Cured material can be removed mechanically.


    Shelf life of 24 months from date of manufacture if kept in a dry store in the original, unopened bags.


    20kg bag yields 10.6L stiff grout, 10.7L plastic grout, or 10.8L flowable grout.

    Additional Information

    CODE 40-FC501020-20KG
    4 Hour Delivery Yes
    U.O.M Each
    Pallet Quantity 48
    Brand Fosroc
    Range / Model Conbextra
    Size 20 kg
    Appearance / Composition Powder
    Application Thickness (mm) 10 to 100 mm
    Cure Time Initial - 5.5 hours, Final - 7.5 hours
    Compressive Strength at 7 days (MPa) 50 (stiff)
    45 (plastic)
    43 (flowable)
    Compressive Strength at 28 days (MPa) 75 (stiff)
    70 (plastic)
    65 (flowable)
    Yield 1.6L (stiff)
    10.7L (plastic)
    10.8L (flowable)
    Class Class A
    Approvals & Certifications AS 1478.2-2005 Appendix E Early Volume Change
    AS1478.2-2005 Table Consistency
    AS/NZS 4020:2005 Products in Contact with Drinking Water
    Fire Rating Class A1 Non-Combustible
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