Development and application of neutron radiography to study concrete, with emphasis on microcracking

Thesis/Dissertation · Thu Jan 01 00:00:00 EST 1987

OSTI ID:5780955

Najjar, W S

Neutron radiography has been successfully developed and used as a testing method for studying microcracking in concrete. Microcracks in a polished concrete specimen are partially impregnated with a contrast agent and subsequently exposed to a neutron flux. The contrast agent is a material with a relatively high neutron-attenuation capacity compared to concrete. Gadolinium has been used as the neutron-attenuating contrast agent, which is applied to a polished concrete surface in the form of an aqueous solution of gadolinium nitrate. When a neutron flux is passed through the specimen, neutrons are readily attenuated by the gadolinium in the cracks, which results in a sharp difference in the flux emanating from the cracked and uncracked areas. Resulting radiographs show cracks not visible to the unaided eye when directly observing the concrete specimens themselves. Air voids are also identified due to their partial impregnation with the contrast agent. The method is evaluated by comparing it with the more-conventional x-ray radiography technique. Neutron radiography appears to be more effective than x radiography for the identification and study of microcracking in concrete. An analytical model developed supports the experimental results. Neutron radiography is successfully applied to study and measure the incidence of microcracking in concrete cylinders as a function of load. This and other applications are described.

• Research Organization: Cornell Univ., Ithaca, NY (USA)
• OSTI ID: 5780955
• Resource Relation: Other Information: Thesis (Ph.D)
• Country of Publication: United States
• Language: English

Related Subjects

07 ISOTOPES AND RADIATION SOURCES
42 ENGINEERING
CONCRETES
CRACKS
NEUTRON RADIOGRAPHY
RADIATION ATTENUATION TESTING
CONTRAST MEDIA
COMPARATIVE EVALUATIONS
X-RAY RADIOGRAPHY
BUILDING MATERIALS
INDUSTRIAL RADIOGRAPHY
MATERIALS
MATERIALS TESTING
NONDESTRUCTIVE TESTING
TESTING
070204* - Radiation Sources- Industrial Uses
Radiometric
420500 - Engineering- Materials Testing