However, the weight loss alone makes 100-ksi rebar a big winner.
“As the steel costs less and less, it makes sense to use it everywhere,” MacNeel said.
Slump Test
Self-consolidating concrete—or SCC—is more flowable than traditional concrete and requires no vibration during placement. However, like 100-ksi rebar, SCC costs twice as much as traditional materials.
So then, which one wins?
The CII team gathered data from several SCC projects and concluded that even though the material was pricier to buy, it delivered 50% lower labor cost than traditional concrete.
“Where it would take four people to place it traditionally, with SCC, because you don’t have to vibrate it, it might only take you two people,” said MacNeel.
Still, SCC does not always offer a net cost advantage. “Generally, I don’t think the labor savings pays for the SCC,” said MacNeel. “But what you do get is higher quality, the flowability and you avoid those pockets and voids in congested rebar.”
On some projects the team studied, MacNeel adds, the rebar designs were so congested that it dictated SCC’s use. That is in part due to new seismic requirements in the Midwest.
“They didn’t have the foresight to get high-strength steel,” MacNeel said. “The joke was that the rebar was so dense, you couldn’t pee through it.”
Form Factor
Modular formwork systems, such as those supplied by Meva, Peri and Doka in Europe, have been in wide use for nearly 10 years in the U.S. However, few have broadly studied their productivity advantages over traditional carpentry.
