Physical, Optical, and Visual Performance of Coated Cross-Laminated Timber during Natural and Artificial Weathering

Gabrielly Dos Santos Bobadilha,Grant Kirker,Katie M Ohno,Dercilio Junior Verly Lopes,C Elizabeth Stokes,Mojgan Nejad

doi:10.3390/coatings11020252

Gabrielly Dos Santos Bobadilha, Grant Kirker + Show 4 more

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https://doi.org/10.3390/coatings11020252

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Abstract

Cross-laminated timber (CLT) market demand is on the rise in the United States. Adequate protective measures have not been extensively studied. The objective of this study was to investigate the weathering performance of exterior wood coatings. We evaluated coated CLT sample surfaces based on visual appearance, color change (CIE*L*a*b), gloss changes, and water intrusion. From the five exterior wood coatings evaluated, only two showed adequate performance after twelve months field exposure. Based on visual ratings following the ASTM procedures, coating failure occurs more quickly in Mississippi than in Wisconsin, due to its greater decay zone. Both location and coating type impacted the aging of the samples. Artificial weathering results were consistent with natural weathering indicating the two adequate coatings were the most resistant to failure, color, and gloss change. For future studies, new coatings designed for the protection of end-grain in CLT panels should be a target of research and development.

Highlights

The use of cross-laminated timber (CLT) in construction has expanded across international markets because of its structural performance, seismic behavior, and sustainability [1,2,3]
We investigated the use of ANN to predict color change based on visual grading on coated CLT naturally weathered in Mississippi [20]
The types of failure present on coatings were mainly fungal growth, cracking, flaking, and erosion, the samples were evaluated according to those characteristics (Table 3)

Summary

Introduction

The use of cross-laminated timber (CLT) in construction has expanded across international markets because of its structural performance, seismic behavior, and sustainability [1,2,3]. CLT was introduced in North America in the early 2000 s, and since research have been developed to expand its use across the building construction sector. Exterior CLT structural materials have been left unprotected, where they are either semi- or fully exposed to weathering [4]. In such conditions, surface degradation of uncoated CLT is very likely. Sun exposure can seriously damage the surface of wood materials since surface photooxidation is catalyzed by ultraviolet radiation [8,9]. The combined effects of moisture and solar exposure are primarily responsible for checking, splitting, surface erosion, and degradation caused by microorganisms [10]

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