Standardization of the neutron probe for the assessment of masonry deterioration

Conference · Wed Jan 01 00:00:00 EST 1992 · Transactions of the American Nuclear Society; (United States)

OSTI ID:6205166

Livingston, R A ^[1]

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1. Univ. of Maryland, Ann Arbor (United States)

The repair of the infrastructure will require nondestructive methods to assess the condition of existing buildings and other structures, many of which are constructed of masonry. One possible technology is the neutron probe, a prompt-gamma neutron activation (PGNA) technique that can perform non- destructive elemental analyses in the field. It is based on a very low intensity [sup 252]Cf neutron source and a high-purity germanium detector for the gamma rays emitted by neutron capture within the material. The thermal neutron capture cross sections for hydrogen and chlorine are very large, and in masonry, these elements are found primarily in moisture and chlorides. These are major causes of deterioration in porous materials such as brick masonry. The moisture damages the material through expansive stresses during freeze-thaw cycles. Chlorides also generate expansive stresses through periodic cycles of dissolution and recrystallization in response to relative humidity cycles in the atmosphere. Similar problems also occur in reinforced concrete, where chlorides cause additional damage through corrosion of the reinforcing steel. The sensitivity of the neutron probe to hydrogen and chlorine thus means it can be used to map the distribution of these agents of deterioration. Preliminary field work at Colonial Williamsburg and Venice, Italy, showed that the technique could yield useful qualitative information. However, to be a quantitative method, the neutron probe had to be standardized in the laboratory on materials of known composition and specified moisture and chloride content.

• OSTI ID: 6205166
• Report Number(s): CONF-920919-; CODEN: TANSAO
• Journal Information: Transactions of the American Nuclear Society; (United States), Vol. 65:1; Conference: 2. topical meeting on industrial radiation and radioisotope measurement applications, Raleigh, NC (United States), 8-11 Sep 1992; ISSN 0003-018X
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
36 MATERIALS SCIENCE
BUILDING MATERIALS
NONDESTRUCTIVE TESTING
CONCRETES
GE SEMICONDUCTOR DETECTORS
NONDESTRUCTIVE ANALYSIS
BUILDINGS
NEUTRON BEAMS
BEAMS
CHEMICAL ANALYSIS
MATERIALS
MATERIALS TESTING
MEASURING INSTRUMENTS
NUCLEON BEAMS
PARTICLE BEAMS
RADIATION DETECTORS
SEMICONDUCTOR DETECTORS
TESTING
440101* - Radiation Instrumentation- General Detectors or Monitors & Radiometric Instruments
360603 - Materials- Properties