Q: Can self-consolidating concrete be used for tilt-up panels? What does the finish look like, and are plastic shrinkage cracks a problem?

A: One of the advantages of self-consolidating concrete (SCC) is its finish. Because it flows so easily, very fine details can be created right out of the form. On tilt-up panels with very fine details or decorative liners, SCC can make sense and it has been used on such panels or where gaining access to the panels was a serious problem and the concrete needed to flow long distances. Jim Baty with the Tilt-Up Concrete Association, Mt. Vernon, Iowa, notes that although he knows SCC has been used for panels, its use is rare and unnecessary in many cases. “I don't think the current cost of the product is justified in most work,” he says.

As far as plastic shrinkage cracking, because SCC has a low water content, good curing is very important to reduce plastic shrinkage cracks and crazing, especially in dry and windy conditions, although that low water also means drying shrinkage will be reduced. The exception is that with very low water contents (below 0.4), SCC can experience autogenous shrinkage, where the cement hydration reaction actually consumes all the water in the mix, leading to some cracking.