Fiber-optic refractive-index sensor for use in fresh concrete

Area of Science:

• Materials Science
• Civil Engineering
• Optical Sensing Technologies

Background:

• Accurate assessment of air-bubble content in fresh concrete is crucial for structural integrity.
• Existing methods for air content measurement can be time-consuming or lack portability.
• Development of real-time, in-situ monitoring tools is needed for quality control in concrete construction.

Purpose of the Study:

• To develop and evaluate a portable fiber-optic refractive-index sensor for real-time detection of air-bubble content in fresh concrete.
• To introduce and validate a novel digital image-processing technique for analyzing sensor signals.
• To assess the sensor's performance in both controlled laboratory settings and practical field applications.

Main Methods:

• A portable fiber-optic sensor system utilizing a low-power visible laser diode was designed.
• Real-time data acquisition and processing were achieved using a laptop microcomputer.
• A new digital image-processing methodology was developed to interpret reflected-light intensity signals.
• Sensor performance was tested on concrete samples in laboratory conditions and during highway construction.

Main Results:

• The developed sensor demonstrated effective detection of air-bubble content in fresh concrete.
• The digital image-processing methodology provided reliable interpretation of the reflected-light signals.
• Laboratory and field studies confirmed the sensor's practical applicability and accuracy.
• The system offers a portable and real-time solution for monitoring concrete quality.

Conclusions:

• The portable fiber-optic refractive-index sensor is a viable tool for assessing air-bubble content in fresh concrete.
• The integrated digital image-processing approach enhances the accuracy and efficiency of air content measurement.
• This technology has the potential to improve quality control and ensure the durability of concrete structures in civil engineering projects.