Slip-forming relied on grace from above, but there was devil’s play, as David Hatch recalls

Story and drawings by David Hatch

David Herbert Hatch is senior pastor at Our Savior Lutheran Church in Green Bay, Wisc. He worked slip-form construction on elevators throughout Iowa in the early to mid-1970s.

Our operations back in the1970s had many vulnerabilities. That is, there were a lot of, “What ifs?”

The whole operation depended on a constant pour. If we had to shut down, we would have, what I remember them calling, a cold seam. That’s when the whole jacking system stopped. The concrete sat in the forms and dried, and everything had to be restarted again at a later time. 

One absolutely ugly seam would be left around the perimeter of an otherwise beautiful structure. Not only that, but the drying concrete might hang up and attach itself to the forms, and they would not go up. So that’s what we tried to avoid.

Remember, I just ran a winch, and I only had hearsay. I was 18 or 19 and trying to gather information. I can only speak from what I know, and that’s not much.

What things could happen to cause such a shutdown?

  • What if an electrical storm lasted several hours and we had to get off the decks because we were a giant lightning rod?
  • What if the power went out in the city? There would be no electricity to run the jack pumps or the lights around the perimeter of the deck or to operate the electric-powered concrete vibrators!
  • What if only a bare-bones part of the crew showed up for work one day? Would there be enough manpower to lay the steel and push the concrete in ratio to how fast the forms had to be jacked?
  • What if the engine on the winch died? There was no back-up winch. (Setting the winch in place was no small matter. It had to be anchored into the ground just right, and angled perfectly so that the cable would wind properly on the spool. If the cable didn’t wrap right, it would rub against itself during wrapping and begin to fray, and then it would not be reliable.
  • Up on the deck was the jack house, where the jack pumps were kept. If I remember right, there were two of them, a primary and a back-up. The chance of going down, it seems, was low.

There were 1,000 other possible troubleshooting challenges. For example, concrete setting up too fast, hanging up in the form during normal operation and “pulling a hole” that would appear below as the forms began to rise. That would not stop the operation, but it sure would be a problem requiring later patching.  If I remember right, the forms were oiled down prior to the start to help prevent this.

David Hatch was born and raised in Ames, Iowa. Prior to college studies, Pastor Dave worked construction and had hopes of serving in law enforcement until his partial color-blindness prevented that. He did not know what to do with his life. Through God’s Providence and a phone call from his sister, who was a kindergarten teacher in Milwaukee, he enrolled in a college where, unknown to him, many of his future classmates were studying to be pastors. He received his education at Concordia College in Milwaukee; Concordia Teacher’s College, River Forest, Ill.; and Concordia Theological Seminary, Fort Wayne, Ind. His pastoral career began in 1982, following seminary, when he served as an admissions counselor at Concordia College in Bronxville, N.Y. and parish pastor at Love Lutheran Church outside of Albany, N.Y.

2 comments on “Slip-forming relied on grace from above, but there was devil’s play, as David Hatch recalls

  1. Brad Perry says:

    The cooperative th

  2. David Herbert Hatch (Text) says:

    Chandler Thomas gives details on two things:

    1.) You wondered how the concrete hoist was anchored to the ground. The most common method was to dig a trench, behind the winch shed, that was perpendicular to the cable, and was approximately 8’ long, 4’ wide and 5’ deep. A railroad tie would be placed at the bottom of the trench. A cable would be attached to the end of both winch frame ends nearest the trench. These cables would be attached to the railroad tie. Concrete would be placed in the trench, often to within 1 foot of the ground surface. Dirt would be placed over the final foot. When the winch was removed, the cables would be dug out to the top of concrete and cut off. The block of con and railroad tie were left in place.

    2.) The term you are looking for when a slip was stopped and restarted is “cold joint”.

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