Anchor Bolt Grouting

What grout is used for anchor bolts?

It depends on how the bolt is installed and what the base carries:

• Cast-in holding-down bolts set in pockets in a new foundation are grouted with a free-flowing, non-shrink cementitious precision grout, such as SikaGrout-214 SA.
• Bolts, threaded rods or rebar fixed into hardened concrete are bonded with a chemical anchoring resin injected into a drilled and cleaned hole, such as Sika AnchorFix-3001.
• Machine bases with vibration, impact or dynamic loads are under-grouted with an epoxy grouting system, such as SikaFlow-400 or Sikadur-42 MP Slow, rather than a cementitious grout.

The common thread is that the grout must fill the space completely and must not shrink. A void or a shrinkage gap under a plate or around a bolt concentrates the load onto a few contact points, which is what cracks a plinth later.

How are cast-in anchor bolts grouted?

Holding-down bolts are set in pockets or sleeves formed when the foundation is cast, positioned to the steelwork, and the pockets are then grouted solid. The grout has to be free-flowing so the pocket fills without voids, and non-shrink so it does not pull away from the bolt as it cures. Sika describes SikaGrout-214 SA as a cementitious, free-flowing, non-shrink precision grout with high early and ultimate strength, suitable for hot and tropical climatic conditions, and lists machine foundations, base plates, bridge bearings and concrete anchors among its uses.

How are post-installed anchors fixed?

Where the bolt goes into existing, hardened concrete, a hole is drilled, cleaned thoroughly and injected with anchoring resin before the rod or bar is set. Sika AnchorFix-3001 is a two-part, thixotropic epoxy anchoring material designed for anchoring threaded rods and reinforcement bars in both cracked and uncracked, dry or damp concrete. Hole cleaning is not optional: dust left in the hole is the usual reason a chemical anchor underperforms its stated load. What an anchor can carry depends on the bar diameter, the embedment depth, the concrete and the edge distances, so the design should follow the data sheet's load tables or Sika's AnchorFix calculation software.

Cementitious or epoxy grout for a machine base?

Cementitious grouts cover most static baseplate and column applications and are the more economical choice at volume. Epoxy grouts are used where the base carries dynamic, vibrating or impact loads, or where chemical exposure rules out a cement-based product.

Sika lists SikaFlow-400 — a three-component, multipurpose epoxy grouting system formulated to withstand static and dynamic loads — for under-grouting machine bases, including heavy impact and vibratory machinery such as reciprocating engines, compressors, pumps and presses, as well as base plates, bridge bearings, anchors and crane tracks. Its listed characteristics include high early strength, moisture tolerance, non-shrink behaviour, corrosion and chemical resistance, and high vibration resistance. Sikadur-42 MP Slow is a three-component, multipurpose, moisture-tolerant epoxy grouting system that Sika lists for the same family of uses. Sika notes that both may only be used by experienced professionals.

Baseplate bedding

Once the bolts are fixed, the plate is bedded so it bears evenly across its whole area. SikaGrout-212 SA is a general-purpose, shrinkage-compensated cementitious grout used for machine foundations, base plates, bridge bearing pads and filling connections; SikaGrout-214 SA is the high-early-strength option. For deep gaps or large areas, ask us — we will match the grout (or a pumpable micro-concrete) to the gap.

Common mistakes

• Dust left in drilled holes. The usual reason a chemical anchor underperforms its stated load.
• Ordinary sand-cement mortar instead of a non-shrink grout. It shrinks back from the bolt and the plate, leaving gaps and point loads.
• Air trapped under the plate. Voided bedding concentrates the load onto a few contact points.
• A cementitious grout under vibrating machinery where the base needs an epoxy grouting system.
• Ignoring the data sheet in Saudi heat. Every grout states its temperature, mixing and curing limits; follow the current Sika data sheet on site.

How much grout do you need?

Send us the plate dimensions and the gap depth, or the pocket sizes and the number of bolts. We calculate the volume and convert it to bags or sets, using the yield stated on the product data sheet.

Need the work done as well?

Alongside supply, we undertake contracting works. For specialist trades we do not carry out ourselves, we can introduce you to contractors in our network, and you deal with them directly. Send the scope rather than a product list and we will come back on it.