In January 2019, Eagle Builders conducted an impact test of their 10-inch thick insulated precast wall panel. The purpose of the test was to better understand how our wall assembly can resist impact forces when struck by objects with significant mass. For this test, Eagle Builders used a 2002 Pontiac Sunfire as their impact object.

“A typical assembly of these precast panels used on the exterior of a building clearly provides an additional level of safety to the occupants as compared to many lightweight exterior wall systems.

Kelly Grubb – Principal, Grubb Engineering Corp.

Construction of the Impact Site.

To set up the test, Eagle Builders used a 35ft (H) x 10ft (W) decommissioned wall panel with a depth profile of 10-inches (3-inch concrete / 4-inch insulation / 3-inch concrete). To best recreate a building application without pouring a structural foundation, flat top concrete blocks were placed in the ground connecting the panel 12-inches below grade. Once the panel was erect, the precast concrete installation crew backfilled and braced the panel using typical shoring. A small precast slab was placed behind the panel with two pins acting as the floor slab.

Setting-up the Test.

The challenge of this test was projecting the car toward the panel while ensuring safety and control of the vehicle. To achieve this, Eagle Builders cored a ½-inch hole through the middle of the precast panel to allow 400-feet of metal cable to pull and guide the object towards the impact location. A Ford F-150 truck with an engineered break-away cable connected to the hitch was utilized as the tow vehicle.

Test Results.

The moving object started off course deflecting to the left of the target. As it was building up speed, the cable continued to pull the car gradually back towards the precast panel. The intent was for the object to hit the center of the panel but as clearly shown in the video, the impact was located on the left edge, hitting the weakest point of the precast panel. At the point of impact, the car was registered traveling at 62 kilometers per hour with the precast panel stopping the vehicle instantly. The calculated impact force with the car weighing in at 2771lbs was 2.43 metric tonnes per sq.ft per of wall area.

Conclusion.

It is without question that a precast concrete wall panel can stop the full force of a car traveling at 62 kilometers per hour. If this same test was conducted using a conventional wall assembly such as wood frame, steel and even concrete block, the probability of the vehicle penetrating the building causing catastrophic damage to the structure and potentially its occupants inside are significantly increased.

 “This demonstration once again helped affirm what we have known all along: insulated precast concrete panels are a robust product capable of safely resisting some very unusual and extreme loads. Although the panel used for this demonstration was not designed to resist this extreme event, but was simply a typical exterior wall panel from a normal building, it was clearly up to the task of stopping the car.”

Kelly Grubb – Principal, Grubb Engineering Corp.

This test also shows that damage to the wall assembly is extremely localized to the impact area. In a real-world scenario, the precast concrete wall segment affected can be produced and installed in as little as 24-hours, greatly decreasing shutdown time.

In conclusion, the extreme durability and modularity of our precast concrete building system offers an added level of security that is above the capabilities of conventional and other lightweight building systems. For areas subject to heavy traffic, severe weather and theft, Eagle Builders precast concrete structural system is an advantageous option for the safety of your building and it’s valuables inside.