ARTICLE: Dry mix vs. wet mix? Drakeley weighs in. / by Lily Samuels

Drakeley Pool Company principal Bill Drakeley contributes to an industry-wide discussion on the merits and uses of wet-mix shotcrete vs. dry mix shotcrete. 



"Guniters will remind you that New York’s Grand Central Station and Holland Tunnel were made with the gunite process, while shotcrete proponents point to new portions of the Weehawken Tunnel and the World Trade Center.

But the truth is probably represented more by the experience of Bill Drakeley, who shotcretes pools but also performs both processes for infrastructural construction. “It’s the type of job, it’s the requirements of the job and then the availability of the materials,” says the owner of Drakeley Pool Co. in Bethlehem, Conn.

Drakeley recently worked on a subway tunnel in New York, training and supervising 147 union workers using both gunite and shotcrete. To cover the 1 million square feet of surface, his crews shot 46,000 cubic feet of wet mix and 11,000 of dry.

“Most of our shooting was high volume, and we had to keep a good pace going,” he says. “The ideal method was wet [when] we could get the material there easily, versus some of the molding or some of the ring steel shooting where we had to use dry [because] we had to start and stop. … Getting a pump truck in certain parts of the tunnel was very, very difficult, so dry came in handy. So it’s the application.”

For the most part, professionals will admit that either process will yield a high-quality product if applied correctly.

“Shotcrete is a process, it’s not a product,” Drakeley says. “Hardened, in place concrete, whether dry [mix] or wet [mix], are equally as good,” he explains. “Once it comes out of the gun and goes onto the surface, your performance should be the same. Your technology is the same, your intentions, your design are all the same.”

It seems to be a matter of which method makes an individual builder or applicator feel more confident, the reputation in a given area and the cost and quality of local plants and workers.

But gunite, in particular, has taken a beating because so much of the quality relies on the workers, who must create the proper mix on-site.

This bad rap has some historic explanation, says Drakeley, who also is a member of the American Concrete Institute’s 506 shotcreting committee main body. “The reason the ACI and specifying engineers kind of look down on pool people is the absolute horror stories that have come out about pool construction over the last 30 years,” he says. “Most of those horror stories are from the dry side.”"

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