Drake Inc. • 402-362-1863 • http://www.drakeinc.net
Reprinted from Grain Journal March/April 2018 Issue
Concrete headhouse deterioration
During 2017, an engineering firm representing a grain handler sent out bids for a concrete headhouse restoration project. The problem involved severe crumbling and deterioration of the concrete walls and corner columns of a headhouse on a roughly 300,000-bushel slipform concrete elevator built with 10 tanks plus interstices in the 1950s.
To make matters worse, the crumbling of the concrete was letting water in to rust out the structure’s reinforcing rebar resulting in even more deterioration.
After bids were received and evaluated by both the engineering firm and elevator owner, a contract for restoration was awarded to Drake Inc., Waco, NE (402-362-1863).
According to Dustin Drake, vice president of the restoration contracting firm, concrete headhouse deterioration has three main causes:
• A lower ratio of cement in the mix at the time the headhouse was built, resulting in less durable concrete.
• Neglect of maintenance and repair over the years, since a headhouse doesn’t house grain, just grain handling equipment.
• The weight and vibration of operating equipment causes damage at a slow but constant rate.
Drake says all three factors were present in this case.
Shotcrete repair
Step by step, here is how Drake Inc.’s repair proceeded once the contract was signed:
• The headhouse surfaces were sandblasted to remove any old paint and prepare them for shotcrete application.
• Holes were drilled in the corners and columns of the structure, then new rebar was epoxied in.
• The structure was sealed using shotcrete, and smaller cracks were repaired with caulking in areas that didn’t receive shotcrete.
Drake wouldn’t give an estimate of how long the repairs would last but noted that the engineering firm had been seeking a 15-to-20-year timeframe.