Hyperspectral remote sensing can capture the chemical and physical changes that occur as concrete cures – offering a non-destructive alternative to compressive strength testing. The method identified spectral markers linked to hydration, moisture loss, and densification, with strong correlations to laboratory-measured strength values.
In a series of controlled tests, concrete cubes of six mix grades were cured over one, seven, and 28 days, with each face scanned using a ground-based hyperspectral system. The resulting spectra showed consistent increases in reflectance intensity as the concrete matured – particularly in regions sensitive to water content and hydration products. These trends aligned closely with conventional compressive strength measurements taken at the same intervals.
To interpret the spectral shifts, the team applied common feature-extraction and multivariate tools used across remote sensing and chemometrics. Differences in reflectance patterns between mixes became more pronounced over time, and principal component analysis revealed that early-age spectra were dominated by hydration-related variability, stabilizing into more uniform patterns by day 28.
In parallel, similarity-based classification successfully matched unknown samples to their correct mix and curing stage.
The work also explored how reflectance changed across the full concrete surface. By gathering dozens of measurements per cube – including corners and center points – the study captured subtle spatial variability that would be masked in conventional destructive tests.
This high-density sampling revealed that even within a single mix, hydration can progress unevenly, and that hyperspectral data are capable of distinguishing these fine-scale differences – an insight the authors say could be valuable for quality assurance in large pours or variable environmental conditions.
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