Tilt-up Concrete Construction

August 9, 2007

About a week ago, I wrote about all the tilt-up construction that is occurring along my route to work. It fascinates me how these giant slabs of concrete are formed on the ground and lifted upright and pieced together to form buildings.

I have very good friends who are in the commercial construction business and I cornered them to give me a quick description of how tilt-up construction is done.

In my drive-by, it looked like the slabs were just poured in frames on the ground. My curiosity was how the slabs could have such smooth surfaces, if they were just formed over dirt. In fact, they are not formed directly on the ground even though it looks that way.

The first step, after proper grading of the site, is to pour the foundation slab for the building.Once this foundation has been poured and allowed to cure (usually several weeks), the slab is treated with some sort of resistor chemical. The frame for a wall is then built on the slab, complete with windows, doors and any decorative elements that were called for by the architect. Concrete is then poured into this framework and again allowed to cure. Next, huge cranes are brought in and they lift the slabs into place. (Oh, I forgot to mention that the frames for the walls have to leave about a 3 foot border all around on the slab.)

My little quickie lesson did not make it quite clear how the corners are tied together, but I believe some metal welding occurs. The wall slabs are really stabilized by the roofing structure which ultimately keeps the created box stable.

That's what I have learned about tilt-up construction.