Insulated Concrete Form Walls Tested for Terrorist Blasts

At a time of increased attention to the possibility of terrorist bombings, the portland cement industry is working with other industry trade associations and the U.S. Air Force to research how well insulated cement-based wall systems can hold up to blast pressures, according to the Portland Cement Association.

At the Marine Corps base in Quantico, Va., the Insulating Concrete Form Association (ICFA) has demonstrated the effectiveness of an insulated concrete form (ICF) wall to withstand an explosive blast equivalent to 50 pounds of TNT from less than one foot away with minimal damage.

The wall that was tested had 2.5 inches of expanded polystyrene on the inside and a 4-inch concrete panel as its outside face.

The demonstration resulted in several briefings with Department of Defense personnel on the viability of ICF and other insulated cement-based wall systems to provide an economical building envelope with improved blast protection.

To further this research, the industry is now providing insulated cement-based panels to the U.S. Air Force Research Laboratory at the Tyndall Air Force Base in Florida. Participating in the effort are PCA’s allied trade associations — the National Concrete Masonry Association, National Ready Mixed Concrete Association, ICFA, Tilt-Up Concrete Association, Concrete Homes Council, Precast/Prestressed Concrete Institute and the Concrete Reinforcing Steel Institute.

Included in the research are several double wythe insulated masonry wall systems, two precast/prestressed sandwich panel systems, two tilt-up concrete sandwich panels, three different insulating form wall systems and an exterior insulated cast-in-place wall. Predictive analytic models, laboratory testing and full-scale explosive experiments are being used in the research.

The researchers are hoping to come up with engineering tools that can be used to predict the blast responses of these commercial-off-the-shelf building systems for both new construction and retrofits to existing structures. For example, for existing buildings that don’t have enough surrounding area to be protected by keeping the explosion at a distance, a solution might be using a precast or tilt-up insulated sandwich panel, with the appropriate architectural treatments already cast-in, as an “armored girdle” around the building’s exterior two or three stories high or adding another masonry wythe with insulation in the cavity of an existing building.

While the blast effects are still being analyzed, the damage observed in research last year with 30-foot precast/prestressed insulated sandwich panels appeared to be minimal.

Portland Cement Association is a member of the National Council of the Housing Industry — The Supplier 100 of NAHB.

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