Grouting steel baseplates

A good quality precision grout, whether resin-based or cementitious must provide good load transfer and be easy to apply under most conditions.

Common issues and queries you can face

Various loads require different grades of high-performance grout

Choosing the right grout

The selection of a suitable bearing grout depends on the machine loading, size of bearing, gap size and grouting method. Choosing the wrong grout can lead to failure of the bearing grout; for example, most cement grouts are not able to resist continuous impact loading such as under vibrating machinery. Cement grouts are weak in tension and undergo fatigue failure. This can have serious repercussions on safety and the cost of remediation can outweigh the initial short-term cost benefit a hundred fold.

Voids in the grout

The support provided by a grout is the Effective Bearing Area (EBA). This can be affected by grout leakage, unlevel plate, shrinkage of grout, inadequate mixing of grout, wrong placement method, poor grout flow or entrapped air voids. EBA can lead to point loading on the grout which in turn can result in cracking and crumbling of the grout under the baseplate. This could have disastrous consequences on the machine.

Cracks in the grout and around the baseplate

Cement grouts rely on expansion to provide the non-shrink properties required of a precision bearing grout. This expansion needs to be confined under the baseplate, but if allowed to expand freely, the grout may crack due to shrinkage. This cracking is often seen where a cement grout has not been finished properly. Epoxy grouts are not affected as much as they have low inherent shrinkage.

Grout not flowing under the baseplate

Rapid installation of machinery is essential. A grout with poor flow will slow down the process. Some inferior epoxy grouts are cut back with diluents to improve flow, but this can lead to excess shrinkage and loss of EBA. Weber grouts have been developed to give good flow without any undesirable side-effects.

Correct grout selection and application

Prepare substrate

The surface of the concrete base must be free of any loose, friable material, be dry and free of dust and laitance and be sufficiently mature not to interfere physically or chemically with the bearing grout.

Holding-down bolts: It is best to grout the holding-down bolts first. This ensures that they have been filled completely. Some specifications call for grouting of anchor pockets and under-plate bearings at the same time; this can lead to air entrapment and voids in the pockets, unless the grout is very fluid.

Removable shims: Steel shims are used to provide the correct levelling and alignment of the baseplate which is then fixed in place using anchor bolts. The shims can be removed or can remain as long as they are corrosion proofed.

Shuttering: Ensure the shuttering is sealed tight to the base to ensure no grout loss.
Choosing an appropriate grout

For high static loads: Use precision cement grouts such as webercem advanced precision grout or webercem advanced precision grout SP.

For vibrating loads, chemicals or high dynamic loads: Use precision epoxy grouts such as webertec EP pourable grout.
Pouring or pumping grout

When pouring the grout into shutters from one side of a baseplate, use a removable hopper to provide an adequate head of grout. The hopper must be a minimum height of 100mm and have a ratio of 1:3 (height of hopper: length of pour).

Grout can also be pumped from the centre of the bearing plate where it spreads to the outside equally on all sides. A peristaltic pump is used for resin grouts and a diaphragm or worm pump for cement grouts. Alternatively, for large grouting areas, a grout lance is placed through the gap to the other side and withdrawn slowly as pumping proceeds.
Ensure edges of grout are finished correctly

Cement grouts should be finished flush to the edge of the steel bearing plate and chamfered at a slope. This is to prevent cracking where the grout is unrestrained. Resin grouts can be left proud of the bearing plates.

Contact us

If you have any questions or would like assistance, please contact our technical team:

Email: technical@netweber.co.uk
Telephone: (01525) 722 100

Our technical team is available Monday to Friday, 8:30am until 5.00pm.

Necessary products for this solution

webercem advanced precision grout SP

Shrinkage compensated highly flowable precision grout

webercem advanced precision grout

Shrinkage compensated flowable precision grout

webertec EP pourable grout

High-strength, chemically-resistant grout

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