Little known to most, Monolithic also builds and uses airforms to make tunnels and bridges as well as culverts. Because of a time crunch in our road construction here in Italy, Texas, we had to just throw in a galvanized culvert under the road. When we were finished we had to concrete the ends so that semi’s, and other vehicles wouldn’t crush the ends of the pipe.
Concrete culverts are fairly common nowadays, but few of them are reinforced, and none of them hold a match to the ones that are sprayed in place. The last project we did we were able to slide the airform tube inside the ends of the standard steel culvert and add on an extra 5 feet of reinforced concrete. The ends being reinforced concrete help protect the culverts from being crushed by a wayward semi.
Monolithic Culverts are fairly simple. First we pour a concrete bottom with rebar sticking up out of it to tie into the steel around the inflated airform. Then the airform is placed inside the rebar and inflated. Once inflated we then tie more rebar to the bars sticking out of the concrete to create a steel grid. Once the rebar is in place we can spray it with about 2 to 3 inches of concrete, not the standard 3000 psi concrete that you commonly find in roads and driveways, but the 8000 psi concrete Monolithic uses in dome construction. Once the culvert is sprayed up the airform is removed.
Check out more images here. For more information about Airformed Culverts go to Monolithic.com.
