Grout is installed under columns to create a firm, even foundation for the column to bear on. When a shear key is not installed, the grout transfers shear loads through friction to the footing. The grout also acts as protection for the anchor bolts which are used to ‘hold down’ a structure from various loads i.e. wind loads.
It is my opinion that grout should be installed to the lower edge of the base plate.
I have noticed that the grout has been installed to the top edge of base plates for many steel structures I have inspected. An example is shown below.
When grout is installed in this manner a ‘bucket’ is formed by the grout around the base plate allowing moisture to pool and seep under the base plate. Over time this will corrode and deteriorate the anchors. This damage is not visible from the surface.
I believe that the reason this method is used in construction is because the form work is easier and cheaper to create.
I recommend that grout is installed to the bottom edge of base plates to prevent this from occurring.
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