Date of Award

May 2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

First Advisor

Sattar Dorafshan

Abstract

The water to cement ratio (w/c) is the primary mix design parameter that will control the strength of a concrete mix. Although a specific w/c is usually stated in concrete mix specifications, there is currently no practical test available that can quickly measure this critical property from fresh concrete. Near-infrared (NIR) Hyperspectral Imagery (HSI) can identify a material by measuring the response of the material to the incident NIR light reflecting off its surface in a range of wavelengths. This measured response can be used to differentiate between unique materials and identify variations of similar materials. This thesis studies the use of the NIR hyperspectral response of fresh concrete as a non-contact tool for determining its w/c ratio. Fresh concrete samples with w/c’s ranging from 0.35 to 0.6 were tested. Multiple spectral feature extraction methods were tried to determine which best could detect changes in w/c. Finally, the change in the hyperspectral response over time was measured. NIR HSI was shown to be capable of predicting the w/c of fresh concrete within ± 0.03 of the design w/c. NIR HSI was also shown to be capable of monitoring the change in free water on the surface of the fresh concrete over the first several hours of the life of the concrete. This thesis is a promising first step in the use of NIR HSI for the quality control of fresh concrete.

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