1. “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
and 1

2. 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

3. 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

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

5. 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

6. Cheop’s (Khufu’s) Pyramid where CTG was used6

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

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

9. Sarcophagus in the Pharoah’s tomb of the Cheops Pyramid9

10. 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

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

12. 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