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Dr. Mohamed Mostafa Mohamed ElFaham :: Publications:

Title:
Optical emission spectroscopy for concrete strength evaluation utilizing calcium lines
Authors: Mohamed M. ElFaham M. Okil , Nabil M. Nagy
Year: 2018
Keywords: LIBS ;Concrete strength ;Halpha-line ;self-absorption;Plasma temperature
Journal: Optics and laser technology
Volume: 106
Issue: October 2018
Pages: 69–75
Publisher: Elsevier
Local/International: International
Paper Link:
Full paper Not Available
Supplementary materials Not Available
Abstract:

Concrete is one of the most important materials in construction engineering. Evaluation of in-Situ concrete strength has become of great concern in construction process as well as for quality control. There are many destructive tests which can be conduct for the strength evaluation and for other performance parameters as well. However, load tests or core tests are not always possible or practicable. Since last decade, non-destructive testing has been widely accepted throughout the world in order to assess the quality of in-situ concrete. Compressive strength is considered as the most common measurement used by engineerings in design. The results of this test indicate if the concrete fulfills the requirements of the desired structure or not. In the present work, the laser-induced breakdown spectroscopy (LIBS) technique has been used as a diagnostic tool for the elemental composition of concrete and determination of the compressive strength. The ratio between the ionic calcium lines at 393.3 and 396.8 nm and the neutral line at 422.6 nm have been utilized to measure their compressive strength. These lines are reversible lines, as they are greatly self-absorbed. The self-absorption of calcium lines under investigation was corrected via comparison of the electron densities. These densities have been measured from calcium lines to that computed from the hydrogen Ha-line at 656.27 nm which are in the same spectra under the same state. A linear relationship has been obtained between compressive strength and the ratio of the calcium ionic to atomic spectral lines intensities (Ca II/Ca I). The results showed an acceptable with high accuracy linear relations. A new relation has been developed for comparison between compressive strength and the plasma temperature. The results reflect the importance of correcting the intensity of the emitted spectral line for the self-absorption effect before utilizing the compressive strength measurement in LIBS experiments. Also, it has been confirmed that the LIBS technique can be considered as a trustful semi nondestructive concrete strength test.

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