“Impact Echo Testing and the Cheops Pyramid”

Larry D. Olson, P.E., Principal EngineerOlson Engineering, Inc.Olson Instruments, Inc.

Wheat Ridge (Denver), Colorado USARutherford, New Jersey (metro New York City)

San Francisco, CaliforniaSocorro, New Mexico

www.olsonengineering.com and www.olsoninstruments.com

Concrete Thickness Gauge CTG-1TF for QA of Thickness of Highway Pavements

• CALTRANS study on Pavement found 0.16 inch thick CTG-1TF accuracy on 8 inch thick pavement (Maser et al, 2003)

Typical Concrete Thickness Gauge Display

• Resonant thickness echo peak at 5.78 inches for a 6 inch thick concrete pavement

• Easy to use push-button Gauge for field technicians

• High quality data saved for engineer analysis

Impact Echo Test

D = Vp/(2*f)D = Thickness/Echo Vp = Compressional Wave Velocityf = Frequency = Beta Shape Factor

Giza Pyramid and Sphinx

Olson Instruments Concrete Thickness Gauge used on Robot in the Cheops Pyramid by iRobot for a

National Geographic 2002 TV Special “ Behind the Closed Door”

Cheop’s (Khufu’s) Pyramid where CTG was used

Stairs ascending from the King’s tomb in the Cheops Pyramid

Vault going up into the internal chambers of the Cheops Pyramid

Sarcophagus in the Pharoah’stomb of the Cheops Pyramid

Vault going into the Queen’s Chamber in the Cheop’s pyramid – Fox Television and National Geographic Investigation of what was behind a small stone door at the end of a 250 foot long, 40 degree angled air shaft with a cross-secton of 8 x 8 inches

CTG Test Head Mounted to Pyramid Rover Robot of iRobotLink to National Geographic Special at www.olsoninstruments.com

The robot crawled up to the stone door for 75 m at a 40 degree angle

CTG Test Head on Gaterbrinck’s Door – Impact Echo predicted2-2.5 inches thick and drilling found door was 2 inches thick –

Note 2 copper pins at top of 8 x 8 inch stone door