Olson - Slab Impulse Response (SIR) System

The Slab Impulse Response method is excellent for evaluating the condition of slab subgrade support. The Slab Impulse Response (SIR) system is designed to identify subgrade voids below slabs-on-grade less than two feet thick. In addition, the Slab IR test method can be used on other concrete structures to quickly locate areas with delaminations or voids in the concrete, if the damage is relatively shallow. Slab IR can be performed on reinforced and non-reinforced concrete slabs as well as asphalt or asphalt-overlay slabs. The Slab IR testing method is often used in conjunction with GPR for subgrade void detection and mapping. Collecting Slab IR data at multiple, densely spaced locations can improve the conclusions by mapping relative areas of higher and lower mobility. Relatively low mobility (velocity/force) and flexibility (displacement/force) qualitatively indicates that such an area appears to be more solidly supported than an area with relatively high mobility and flexibility.