Identify Subgrade Voids
The Slab Impulse Response (SIR) method is used primarily to identify and map subgrade voids below slabs-on-grade, although it also sees use in general condition evaluation of structural elements. This method is excellent for evaluating the repair of slab subgrade support conditions by comparing the support conditions before and after repairs. The SIR method is often used in conjunction with Ground Penetrating Radar for subgrade void detection and mapping.
The SIR method has been used on slabs of a wide range of thicknesses, but is most effective on thinner slabs (less than 12 inches thick). The method is generally limited to slab thicknesses of less than about 20-24 inches in thickness for most applications.
An alternate application of the SIR method is in the general evaluation of the condition of concrete structures. In this application, the method is used to look for low-stiffness areas associated with hidden damage such as honeycomb, void, and cracking. The method can be used for a fast evaluation of structural conditions, with a more detailed investigation than performed with Impact Echo or Ground Penetrating Radar.
Applicable On:
Concrete Structures
Reinforced and Nonreinforced Concrete Slabs
Pavements
Runways
Spillways
Pond and Pool Bottoms
Tunnel Liners
Asphalt or Asphalt-Overlay Slabs
Test For:
Subgrade Void Detection
Evaluating Repair of Slab Subgrade Support up to 2 Feet Thick



The SIR System
Diagnose Defects
Identify and map subgrade voids below slabs-on-grade
Evaluate
General condition evaluation of structural elements

Comparison
Evaluate the repair of slab subgrade support conditions by comparing the support conditions before and after repairs
Variety of Applications
Test on concrete slabs, pavements, runways, spillways, pond and pool bottoms, and tunnel liners
Combine Methods
This method is often used in conjunction with GPR