“Impact Echo Testing and the Cheops Pyramid” Larry D. Olson, P.E., Principal Engineer Olson Engineering, Inc. Olson Instruments, Inc. Wheat Ridge (Denver), Colorado USA Rutherford, New Jersey (metro New York City) San Francisco, California Socorro, New Mexico www.olsonengineering.com and www.olsoninstruments.com 1

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) 2

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 3

Impact Echo Test D = bVp/(2*f) D = Thickness/Echo Vp = Compressional Wave Velocity f = Frequency b = Beta Shape Factor

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” Giza Pyramid and Sphinx 5

Cheop’s (Khufu’s) Pyramid where CTG was used 6

Stairs ascending from the King’s tomb in the Cheops Pyramid 7

Vault going up into the internal chambers of the Cheops Pyramid 8

Sarcophagus in the Pharoah’s tomb of the Cheops Pyramid 9

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 10

CTG Test Head Mounted to Pyramid Rover Robot of iRobot Link to National Geographic Special at www.olsoninstruments.com The robot crawled up to the stone door for 75 m at a 40 degree angle 11

CTG Test Head on Gaterbrinck’s Door – Impact Echo predicted 2-2.5 inches thick and drilling found door was 2 inches thick – Note 2 copper pins at top of 8 x 8 inch stone door 12