Exposed aggregate tilt-up panels are helping some architects, engineers and builders produce good-looking buildings at low costs. The technique combines the economy of tilt-up construction with the beauty of exposed aggregate. Some contractors have been able to produce exposed aggregate walls for about 10 cents a square foot more then for a plain-troweled concrete tilt-up wall.
One exposed aggregate tilt-up project, the 125,000 foot Houston Central Warehouse illustrates the method. The wall panels were cast face up on the floor slab. Ready mixed concrete was spread in the forms, struck off and the aggregate for exposing placed into it. As soon as the concrete surrounding the aggregate had reached its initial set, it was cleaned off, exposing the attractive stones. After curing, the panel were tilted into place with a motor crane. Once tilted up, the panels were held in place by casting concrete columns between them. The contractor cast 20 foot wide, 25 foot high panels at the rate of 6 a day using a crew of 14 men, most of them laborers.
One contractor figures that the wall cost is about 10 cents a square foot more than that of plain finished tilt-up panels. One reason for the small differential is that the use of exposed aggregate, while it takes extra time to place it and extra expense for the rock, it saves times time in finishing that would be necessary on a plain panel.