At the most recent meeting of the American Concrete Institute in New York City, Senior Editor Joe Nasvik and I had the opportunity to meet with some of the people who are taking the concrete message to the streets of New York (Joe's story starts on page 40). The facts are compelling, and developers in New York, notoriously a steel-only town, are listening.
I sat down with two of those who are ambassadors of concrete in New York, Mike Mota, a regional structural engineer with the Portland Cement Association, and Carl Adler with Quadrozzi Concrete Corp., a major ready-mix supplier to the city. Here are their key points:
- 9/11 is a factor in that all buildings in New York City now require a heavy concrete fire escape core. Since the concrete contractor is building the core, he or she can also provide a very competitive bid on the building frame and flat slab decks.
- With taller buildings;, a concrete frame structure is stiffer, which results in lower accelerations from wind forces—less perception of motion—and therefore a greater feeling of comfort.
- Concrete offers shorter lead times for startup of construction than does structural steel, which has long waits for special ordered shapes. There's also less money committed upfront with concrete.
- There are 8 to 10 contractors in New York and 2 or 3 ready-mix producers who can build high-rise concrete buildings. They have developed good working relationships and a successful team approach.
- Although there are no ready-mix plants in Manhattan, there are producers in the surrounding boroughs who can easily deliver concrete anywhere in the city. Quadrozzi is now producing higher strength concrete—up to 12,000 psi compressive strength— which allows smaller columns; concrete up to 12,000 psi does not require any special treatment for fire resistance under ACI 216, "Fire Endurance of Concrete Elements."
- Concrete offers an energy savings in that its thermal mass reduces the temperature swings. This can provide points towards tax breaks under New York's Green Building Tax Credit and LEED points for sustainable construction.
- There is growing interest among architects for using exposed aggregate suraces on buildings.
Developers and architects in New York are looking at concrete for all these reasons. If concrete can make it there it can make it anywhere (sorry, Frankie, I couldn't help myself).
Editor in Chief