Curved Concrete Barriers
For the past two years, we at Stone Soup Concrete have been involved in a project that has been quite special to us, and quite different from our core concrete countertops and sink work. The project involved the creation of 24 identical objects that were intended to resemble Jersey barriers. But unlike the barriers found out in the wild, these were to be curved, not straight. And as they were to be shown in museum galleries, rather than used as security sentinels for the museums, they needed to be light enough to not cause structural strain on the exhibit floors.
The Barrier project, as it came to be known was a collaboration between 2 NY based conceptual artists working under the moniker Type A, 3 regional museums*, and Stone Soup Concrete. The piece, and the project’s evolution became a metaphor for the instability of the times we now find with us. Soon after the project was started one of the sponsoring museums was closed by the university that supported it… in order to liquidate the art holdings and make up for budgetary shortfalls. Fortunately another museum was found to take its place, or the entire project would have foundered. Shortly after that, the company we had engaged to do our full-scale rendering went belly-up.
Working with artists who had no material connection with concrete was much akin to the kind of translation we have to do in our more prosaic work. Until the first barriers came out of the mold, the artists had only experienced them in renderings and in very small 3D printouts. So much time was spent exploring both the limitations, and the strengths of concrete. It wasn’t until the artists saw the full scale objects in our shop that they really got a visceral sense of how these objects would actually occupy space.
Working with museums was also an eye-opener. Within those institutions sponsoring the Barrierproject, there was quite a particular social structure. On one hand there were the curatorial staff, whose job was to select, schedule, and arrange artists, attending to their needs, publishing publicity and archival materials, and managing the labor required to get artwork installed and shown. On the other side of things were the museum preparitors. Generally artists themselves, it was their job to do the actual physical work of installing and sometimes even creating the artwork that increasingly conceptual artists could not make for themselves.
And the actual mechanics of producing these objects proved quite a departure from the kind of work we generally do at Stone Soup Concrete. We typically make custom objects. Each one is different from the last, and forms are made with that sort of durability in mind.
But with Barrier, we had to make a form that would not only withstand multiple uses, but could be used to produce large and heavy objects, quickly and consistently. If cast solid, these objects would weigh 5,000 lbs. In order to fulfill their role as a museum exhibit, the barriers had to be as light as possible. They had to withstand close examination, seem solid, and survive the rigors of New England weather.
It was an interesting project.
Finding the form.
Jersey barriers are often large. And in the wild, they are never curved. So some consideration was put into the method by which the form could be found. We had some basic information to start with; an end profile, an arc length, a CAD rendering, and a small 3D printout. The final barriers were to be 7’-9” long, 37” wide at their base, 8” wide at their top, and travel through 60 degrees of arc. Six could make a circle a little over 20’ in diameter.
Although there were other methods available to us, we elected to have a full-scale rendering commissioned. This way we could work out any details before building the mold. At the same time we got a mold we would use for the interior foam casting. This foam plug would allow the barriers to have a 1” wall thickness, as well as 2” thick arched pathways to more effectively deliver concrete. The arches would also act as structural coffers.
Once we had the CNC foam masters in hand, fiberglass shells were created. Into the interior shell we poured an expanding urethane foam to make the plug. Once released, 7/8” stand-offs were inserted to assure the plug would stay centrally located within the outer form.
The exterior shell had to be mounted into an assembly that would both be a mother mold (a structural casing) and casting machine. We would cast the concrete from the top, then once set, eject the casting from the bottom.
Because these barriers are curved, I was fairly certain that they wouldn’t just fall out of the form. And because of the curve, there was no way to ‘yawn’ the form open to ease the casting’s ejection. The barriers also needed to have a formed undercut, which would provide a shadow line allowing for strap pathways and any needed shims to be hidden out of view.
So the casting assembly was built in three major parts. A concave side which was rotated within a mobile chassis, a convex side which slides away from the concave side when the form is inverted, and an undercut form that would prevent the foam plug from being enthusiastically ejected during the casting process. The undercut form is removed prior to the ejection of the casting.
There were also three minor parts. A rubber cap was placed along what would ultimately be the top extremity of the barrier. This would allow pressure to be expressed downward against the barrier to eject it from the mold. Two foam inserts were also attached to the terminal faces of the mold. All three of these pieces were also used to hide the longitudinal split in the fiberglass shell.
Casting the barriers.
The walls needed to be thin, if the weight was to be kept low. We wanted to avoid the possibly form damaging effects of vibration, as well as the extra work of steel reinforcement. So this became a perfect job for GFRC.
We used a mix that was one part sand,one part cement, 50% (by volume) fibers, and 33% (by weight) water/Forton 774 mix. Adva 555 was used as our water reducer.
Each barrier took about 850 lbs. of concrete to fill. Once we were up to speed, a crew of 3 was used for casting. The casting process took about 2 hours. A day later, it took an hour or so for one person to get the finished casting out of the form. It then took another hour to prepare the form for the next casting. We were able to cast three each week while also producing other work.
But it didn’t start that way. There was a bit of a learning curve. For first barrier, we tried to use a much more sand intensive GFRC (aka Bad GFRC) It took 5 of us over 5 hours to fill the form, and it didn’t’ fill that well, even though we added a huge amount of extra vibration.
When we pulled the barrier out, that took just as long. And it pulled a beautiful blue color out of the fiberglass gel coat. Our artist clients were a bit apprehensive when I sent them pictures.
The second one revealed a few more flaws in our methodology. By this time we had decided that good GFRC was better than bad GFRC. And it flowed into the form… and it flowed. By the time the form had gobbled 1100 lbs. of concrete, we were sure that something was amiss. And sure enough it was. Part of the mother mold was collapsing under the strain, causing huge lumps on the inner part of the barrier. We only had one mold, and the foam master have been destroyed in the fiberglassing process. So there were some concerned faces around the shop that day.
The next day we took it out of the form. And although there were lumps, the second one was much cleaner than the first. More importantly, the form had survived. So we fixed the form, and carried on.
Every subsequent barrier came out well… though with far more surface individuality than we expected. If placed with each other, they were certainly unified as a type. But individually they were all unique. And as they were all Jersey Barriers, they soon became Jersey Girl Barriers. Whether it was Lisa, Diane, Geri, or Cassandra, each girl got a name.
Delivering the barriers.
We built special J bars to jack and move the barriers in close quarters. And as they only weighed 850 lbs. they could be moved around on dollies. This allowed them to be easily loaded onto a box truck for transport. Once on site, they could be easily maneuvered into place, and dropped to ground.
For our last installation, it took 4 guys 3 hours to install 16 barriers.
Jersey barriers are banal and ubiquitous objects. Developed by the NJ Department of Transportation it is a modular traffic divider that is designed for ease of mobility and quick installation. They are everywhere, and almost invisible except for their metaphoric strength. They demarcate space. They are designed to prevent things for happening. They say, “Stay away.”
But the barriers of Barrier are different. Children climb on them. Adults sunbathe on them. People approach them and caress them. It is almost as if they had been made of a special material. And in a way they have.
Concrete is a meditation. After thousands of years it is barely understood. Yet this is a material that because of its ubiquitous deployment, and proven durability, its name is synonymous with credible truth. For most of us that use it, it remains a mystery. And it is that mystery that has drawn us to it. For most of us in this business, it was the material itself that became our muse, and not the blessings of a concrete countertop business.
In the new economy, and in our familiar markets, concrete has been recently cast as a commodity. Large countertop shops have tried to get into this material, and have tried to reduce its trade to an exchange of commodity for cash. I place no blame here. Business is a major cultural engine. And simplicity serves the efficacy of exchange.
For me, Barrier is a potent metaphor. Wild Jersey barriers sell for $250, and weigh 5,000 lbs. or more. They form a formed pillar of our society, and are the basis for many a sound business. They are everywhere, nobody sees them, and nobody wants them unless they absolutely have to avail themselves of their service.
But add a curve, and everything changes. A stultifying object becomes intimate and artful. It becomes aesthetically significant, and individually valuable. Making such objects cannot exist within the world of those who push baubles, even if they are also bollards. Individuality cannot withstand individuation.
It is unfortunate that the makers of craft concrete furnishings have assembled themselves under the banner of fabricators of concrete countertops. And although this is where many of us make the bulk of our income, it is not what drew us to this material. It was the special curves and unique turns that make what we do worth doing. After all, the winding path covers the most ground.
I have an ability to offer something greater than another piece of proprietary stuff, made overseas, and covered with a salesman’s gloss. I can offer my customers a glimpse of their own destiny through the beauty of the perfectly flawed material. I can turn a faint ghostly apparition, into something real and tangible.
I work in concrete.
Tang Teaching Museum, Saratoga Springs, NY
De Cordova Sculpture Garden & Museum, Lincoln, MA
Aldrich Contemporary Art Museum, Ridgefield, CT