Concrete density estimation of linac bunker walls using impact-echo testing.

Area of Science:

• Materials Science
• Non-Destructive Testing
• Civil Engineering

Background:

• Newly constructed bunkers require integrity checks before critical equipment installation.
• Visible honeycombing in a bunker necessitated an assessment of its shielding capabilities.

Purpose of the Study:

• To estimate the concrete density of a newly constructed bunker using impact-echo testing.
• To confirm the bunker's shielding integrity prior to linear accelerator installation.

Main Methods:

• Impact-echo testing was employed, utilizing the propagation and reflection of elastic waves.
• Mechanical impact generated stress pulses, with reflected waves analyzed for dominant frequencies.
• Concrete density was related to measured P-wave velocity, assuming known elastic modulus and Poisson ratio.

Main Results:

• Validation tests achieved density estimates within 3% of true values.
• Measured velocities on the honeycombed wall ranged from 3750 to 4300 m/s, corresponding to densities of 2201–2894 kg/m³.
• The majority of estimated densities fell between 2307 and 2544 kg/m³.

Conclusions:

• Impact-echo testing is a viable method for assessing bunker shielding integrity.
• This technique provides crucial data before the installation of sensitive equipment like linear accelerators.