HANCOCK, Minn. - They make concrete pipes, and build and repair manholes, culverts and bridges. Sometimes, the words these workers used would make the air turn blue.

"When I first got out of high school, I worked on the slab," recalled Rob Schmidgall, chief executive officer of Hancock Concrete, referring to the company's outside production line. "I learned words I never thought were possible to learn."

Now, there are different lessons to be learned at Hancock Concrete, headquartered in the lake country of west-central Minnesota. And a big one is that swearing is not OK.

At one of the entrances to the plant, about 135 miles southeast of Fargo, a big poster lists the rules: "No swearing; No jerks; We like what we do," and "Have fun."

"The first two are really to allow the next two to happen," said David Schmidgall, Hancock Concrete's vice president.

"We're trying to promote an environment in which you want your children to work," he said.

It's not always an easy sell to these tough workers.

"There's still struggles," said Josh Nohl, one of the Hancock Concrete supervisors who works in production. "Amazingly, most of them catch themselves and apologize. It's gotten a lot better. And the more you don't do it, the more you notice it when people do."

Hancock Concrete, founded by the Schmidgall family in 1916-17, has about 320 employees spread over six sites in Minnesota, Iowa and the Dakotas. Its hometown of Hancock, rooted in faith, family and farming, had a population of 765 in the 2010 census.

The company founded by Henry Schmidgall produced its first reinforced concrete pipe in 1925, its website says. In 1972, Henry's grandson, Neil, founded Superior Industries in Morris, about 10 miles from Hancock, to make conveyor systems. Superior acquired Hancock Concrete in 2011, bringing the family businesses together. They have a combined workforce of about 1,600.

Hancock Concrete lists about $52 million in annual revenue. It is a nonunion shop with starting pay about $13 an hour, but good performers move up quickly, Rob Schmidgall said.

David Schmidgall said the no-swearing and no-jerks rules, which have been in place for at least five years, make up a guide for new employees.

"It's really a safety principle, a principle of self-control," he said. "Ultimately, it's about mutual respect."

Hancock Concrete has never fired anyone just for profanity, and there's no list of forbidden words, he said. If a worker doesn't stop swearing, the supervisor may talk to that worker or document the incidents. The goal is coaching, not punishment, Schmidgall said.

"Consistently setting expectations has always seemed to work," he said, and "people either appreciate this about us or they end up leaving on their own."

He recalled one time when a raise was withheld from a worker who repeatedly swore, but "he quickly turned around and we were able to reward his choice."

Schmidgall tells new recruits that George Washington court-martialed more than 50 soldiers for profanity. Blaming salty language on construction industry jobs - "I think that's a cop-out," he said.

For some workers, it was like going on a diet.

"I swore my whole life and I'm not saying it's right, not saying it's wrong," said Tom Staton, a maintenance supervisor who has been at Hancock Concrete for about 9½ years. If someone had told him years ago to quit swearing, he said, "I'd probably tell them to go you know where."

He's come around.

"A few of us got talked to. It was more or less people telling on you. That upset me more than anything," he said. Still, he said, "I'm 56 years old. I understand if you want a job, you've got to work with it."

"When you're in charge, you've got to kind of control it (swearing) a little bit. It's not like it was 30 years ago," Staton said. "The culture has changed a lot. I don't like being talked to that way, so I don't want to talk to my guys that way."

Jonathan Hyman, a Cleveland, Ohio, labor attorney who has written about workplace law and other job-related issues, said that in the 20 years he's been in the business, he's never had a client come to him and say, "We want a swear-free workplace."

"In the construction industry, it strikes me as pretty rare," Hyman said. A no-swearing policy can stand if employers make it clear they are not infringing on workers' rights to try to speak up for better wages or working conditions, he said.

At Hancock Concrete, David Schmidgall said he has given bonuses to employees who cut down on their swearing because it shows growth. The level of profanity is a leadership indicator "in the same way safety, quality, housekeeping, employee morale and even attendance are," he said.

"If they need help, I help them. I'm not the guy pointing fingers," Marty Flicek, another supervisor, said of his philosophy dealing with the issue.

Krissie Rose, a safety coordinator at Hancock Concrete for about 3½ years, reports a "huge" improvement in the incidents of swearing in the production area, though she never heard a lot of it around the office.

"It can be hard to stop, but if you just think before you talk, it's not difficult," she said via email. "Yes, I have caught myself doing it when in certain situations. As soon as I catch myself, I correct myself and apologize to whomever I'm with. If I catch someone else swearing, I correct them and tell them they need to think before they speak."

"I tell them, 'I'd rather you didn't swear and there's better ways of expressing yourself,' '' said Geoff Richardson, a quality control supervisor. "For the most part, people are more careful.

"It's a noble goal and so you want to respect that. And it makes you try a little harder," Richardson said.

"We're not trying to tell the world not to swear, but these are our standards," David Schmidgall said. It's a way of trying to make work less stressful and "a small way we can make the world a better place and our homes a safer place," he said.