การพัฒนาวิธีการทดสอบการเสื่อมสภาพของคอนกรีตด้วยรังสีอินฟราเรดแบบใกล้

Abstract

This research is an attempt to develop new non-destructive testing technique to determine the chemical compositions of the deteriorated concrete structure. The development started with the usage of “Near-Infrared Spectrometer” (NIR Spectrometer) to study the unique optical properties of deteriorating substances or related chemicals such as chloride ion, calcium hydroxide, or sulfate. These substances show unique reflectance and absorbance to infrared ray with specific wavelength. It was found that the concentration of each substance in cement paste specimens can be calculated from the second derivatives of absorbance spectrum. Consequently, the obtained knowledge of optical properties can be applied to measure the distribution of substances on two-dimensional concrete surface by using “Near-Infrared Spectral Imaging System”. The results obtained from this newly-developed technique are very similar to those obtained from EPMA analysis while the operation is much easier.