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We describe the construction of a concrete taco to provide an
example of how all elements are combinations of simple
geometric forms. When the taco is broken down into simple
elements, each element has a procedure for accurate
construction. These procedures can then be combined to
correctly build any obstacle. However, if you have an element
that you find is difficult to break into simple geometric
forms, give us a call.
A taco or similar obstacle has a radial transition on the
front and a flat bank on the back. The two elements rise to
meet at a curved piece of coping in the same manner as a
spine. So, if we break this type of obstacle down into its
constituent parts we can see that the coping will require
fabrication and assembly like the coping for a bowl. The
coping must have legs in order to be self supporting in the
same manner as a spine. Additionally the radial transition in
front will need to be built like a bowl wall, and the back
like a flat bank. So, in this example at least four separate
elements of construction are being combined to begin work on
the obstacle. To begin, the pre-bent coping is welded and
legs are attached so that the coping is at the proper height,
angle to the ground, and is free-standing. Then, earth and
gravel are brought in and compacted. The goal is to get as
close as possible to the finished form (minus the depth of the
concrete). This requires a transitional radius excavation jig
for the front. After excavation is complete, lower forms are
built around the obstacle on all sides. This combines the
principles of straight and curved shaped flat-work forming as
outlined in previous sections.
Two screeds then need to be fabricated including an 8-feet
transitional radius screed for the front of the obstacle, and
a flat bank screed for the rear. To maintain speed and avoid
a “kink”, a radius can be added to the bottom of the flat bank
screed. In both instances, the screeds will slide along the
coping (spine) from above and the wooden form boards below.
Always perform a test run before using a screed to place
concrete. The concrete for the obstacle is then placed and
finished in the manner that each part of the shape dictates.
After the concrete has set, the forms are removed and the
concrete residue cleaned from the coping.
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