Slab Impulse Response

The Slab Impulse Response (SIR) method is used primarily to identify and map subgrade voids below slabs-on-grade.

  • Fast, one-sided testing
  • Most effective on thinner slabs (less than 12 inches thick)
  • Limited to slab thicknesses of less than 20 to 24 inches

SIR can be used to:

  • Evaluate the support conditions before and after repairs of slab subgrade
  • Look for low-stiffness areas associated with hidden damage (honeycomb, void, or cracking) for general assessment of concrete structures
  • Subgrade void detection and mapping, in conjunction with Ground Penetrating Radar

Applicable on:

  • Concrete Structures
  • Reinforced and Nonreinforced Concrete Slabs
  • Pavements
  • Runways
  • Spillways
  • Asphalt or
    Asphalt-Overlay Slabs
  • Pond and Pool Bottoms
  • Tunnel Liners

Test for:

  • Subgrade Void Detection
  • Evaluating Repair of Slab Subgrade Support up to 2 Feet Thick

The SIR System

The Slab Impulse Response method is excellent for evaluating the condition of slab subgrade support.

  • Diagnose Defects
    • Identify and map subgrade voids below slabs-on-grade
  • Evaluate
    • General condition evaluation of structural elements
  • Combine Methods
    • This method is often used in conjunction with GPR
  • Variety of Applications
    • Test on concrete slabs, pavements, runways, spillways, pond and pool bottoms, and tunnel liners
  • Comparison
    • Evaluate the repair of slab subgrade support conditions by comparing the support conditions before and after repairs