Nondestructive Evaluation of Water-based Polymer-isocyanate Adhesive Distribution in Glued Laminated Timber Using X-rays

Abstract

The objective of this study was to develop a nondestructive method using X-rays for evaluating the distribution of adhesive resin in laminated timber glued with a water-based polymer-isocyanate adhesive (glulam). X-ray radiographs of laboratory-produced glulam were taken before and after gluing. The distribution of adhesive resin in glulam was evaluated by comparing brightness values on the radiographs. Two validation experiments revealed that the method showed high accuracy in estimating both the average and local spread rate and could provide a clear visualization of quantitative trends in the distribution of resin in glulam. The method allows us to nondestructively evaluate the distribution of the studied adhesive resin in each glulam, suggesting that X-rays are not only useful for various fundamental studies relating to wood adhesives but also suitable for industrial application..