Feasibility Study of Prompt Gamma Neutron Activation for NDT Measurement of Moisture in Stone and Brick
Rick L. Paul
The deterioration of stone and brick architecture or sculpture often involves damage caused by moisture. The feasibility of a non-destructive testing (NDT) method based on prompt gamma neutron activation (PGNA) for measuring the element hydrogen as an indication of water is being evaluated. This includes systematic characterization of the lithology and physical properties of seven building stones and one brick type used in the buildings of the Smithsonian Institution in Washington, D.C. To determine the required dynamic range of the NDT method, moisture-related properties were measured by standard methods. Cold neutron PGNA was also used to determine chemically bound water (CBW) content. The CBW does not damage porous masonry, but creates an H background that defines the minimum level of detection of damaging moisture. The CBW was on the order of 0.5 % by mass? for all the stones. This rules out the measurement of hygric processes in all of the stones and hydric processes for the stones with fine scale pore-size distributions. The upper bound of moisture content, set by porosity through water immersion, was on the order of 5 %. The dynamic range is about 10-20. The H count rates were roughly 1-3 cps. Taking into account differences in neutron energies and fluxes and sample volume between cold PGNA and a portable PGNA instrument, it appears that it is feasible to apply PGNA in the field.
AIP Conference Proceedings,40TH ANNUAL REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION: INCORPORATING THE 10TH INTERNATIONAL CONFERENCE ON BARKHAUSEN NOISE AND MICROMAGNETIC TESTING, VOLS 33A & 33B
Feasibility Study of Prompt Gamma Neutron Activation for NDT Measurement of Moisture in Stone and Brick, AIP Conference Proceedings,40TH ANNUAL REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION: INCORPORATING THE 10TH INTERNATIONAL CONFERENCE ON BARKHAUSEN NOISE AND MICROMAGNETIC TESTING, VOLS 33A & 33B, Baltimore, MD, US, [online], https://doi.org/10.1063/1.4864907
(Accessed December 2, 2023)