Casting Bigger Than Usual Bolts Into Concrete

Here is a formwork bolt assembly we used to cast some 40 KG bolts into a 5 meter high pedestal. The assembly includes a pre-fabricated Shear Key (which is always fun) :)

Click the images for a larger more detailed picture.

Bolt Template

Bolt Template

The bolt template is made from steel in order to support the weight of the bolts. The template must have the Center Lines scribed into it in order to place it into the correct position.

The template is clamped onto aluminium formwork beams. The beams are secured onto the formwork shutter with a timber and Z-Bar holding-down assembly.

The center of the bolts was marked onto each side of the forms and a string line was stretched across.

Then we used either a plumb bob, or spirit level to align the string line with the scribed centers on the template.

Doing this positions the bolts pretty close, but not close enough for a mining job. Later surveyors will come and check the bolt centers and each bolt position.

The total weight of the bolts is 480 kg. It is essential to get the assembly positioned as close as possible so that it makes it easier to lever into a spot-on position with the surveyer.

The Bolts

For safety reasons, we found it necessary to lift these bolts in one at a time with a crane.

40 KG Holding Down Bolts Spanner Bolts Inserted Into The Template

Tolerance Tubes

After the bolts are in, polystyrene Tolerance Tubes must be added to the bottom of the bolts at the correct height. The height was established and scribed onto the formwork shutter, then transferred onto the bolts with a spirit level.

Tolerance Tube Height Add the Tolerance Tubes

Adding the Shear Key and Bottom Template

The Shear Key was added next. After that the bottom template made from form ply was added.

A hanging assembly made with timber and z-Bars was used. The Z-Bars were used to wind the Shear Key up until it buts up tightly into the Spreader Bar timber holding it firmly in position.

Shear Key Hanger Shear Key Bolts with Shear Key and Bottom Template

The Z-Bars are also used to “Crack’ the Shear Key after the concrete is poured. Crack the Shear Key while the concrete is soft (Don’t wait till the next day).

Concrete Finished

One down, 7582 to go :) Personally, I’d rather be fishing.

Shear Key Stripping Poured and Stripped

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