Photodegradation of Bamboo: A Study on Changes in Mechanical Performances

Abstract

One of the main concerns in using natural materials in construction, such as bamboo, regards their durability. Ultra violet (UV)irradiation is claimed as a damaging agent; therefore, it is important to study its effect. Several studies have shown that bamboo components such as lignin are subjected to photochemical degradation, but it is not well understood how this affects the mechanical properties of bamboo. The aim of this paper is to explore the correlation between photodegradation and bamboo mechanical performance. Bamboo samples were exposed to accelerated UV ageing for different times (from 6 to 360 h) and then subjected to a four-point bending test. Since one of the ways to stabilize bamboo is to thermally treat it, the tests were conducted on natural untreated bamboo and treated bamboo with a traditional flame treatment. Modifications of the chemical features of the material were analyzed with Fourier Trasform Infra Red (FTIR) spectroscopy, while modifications of the morphological features were analyzed byEnvironmental Scanning Electron Microscopy ESEM and optical microscopy observations. The results show that the bending behavior of bamboo is not compromised by UV exposure up to 360 h. In fact, although a progressive degradation of lignin is reported and cracks in the fiber walls are highlighted from micrographs, no effects were found on the fiber length.

Bamboo as Sustainable Building Materials: A Systematic Review of Properties, Treatment Methods, and Standards

“…Greco et al [75] investigated the impact of ultraviolet (UV) irradiation on the mechanical properties of bamboo culm, in both dried and untreated samples. The research revealed that UV exposure for up to 360 h resulted in a decrease in the lignin content and surface changes, but it did not compromise the longitudinal fiber structure.…”

“…The International Standards used includes (1) ISO 22157-2019 [1, 16,54,74,75]: 2004 [8,14,15,17,24,27,92]: test methods for determination of physical and mechanical properties of bamboo culms; (2) ISO 22156 [77,98]: bamboo-structural design which basically concerned with the requirements for the mechanical resistance, service and durability of bamboo structures; (3) ISO 12122-1 [42]: determination of the characteristic values for a defined population of timber products; (4) ISO 19624 [15,42]: basic principles and procedures of the grading of bamboo culms for bamboo structures; (5) ASTM D143 [44,63,64,84]: standard test methods for small clear specimens of timber; (6) ASTM D3379-75 [91]: standard test method for tensile and young's modulus for high-modulus single filament materials; (7) ISO 9427 [91]: methods of determining the density of wood-based panels; (8) ISO 16979 [59]: determination of the moisture content of wood-based panels; (9) ASTM D1037-12 [48,91]: standard test methods for evaluating properties of wood-based fiber and particle panel materials; (10) ASTM D3039 [10]: standard method for tensile testing composites; (11) ASTM 3043-00 [44]: standard test for structural panels in flexure; (12) ASTM D7078-12 [44]: standard test method for shear properties of composite materials by V-notched rail shear method; (13) ASTM 5266-99 [44] standard practice for estimating the percentage of wood failure in adhesive joints; and ( 14) ASTM D3822-07 [78]: standard test method for tensile properties of single textile fibers.…”

“…Another is the BS EN 408 [24], which guides the determination of some physical and mechanical properties of timber structures and glued laminated timber. Italy has UNI 11842-2021 [75], which governs the test procedures for the mechanical characterization of bamboo culms. Greco et al [75] used this in their investigation of the photodegradation of bamboo in UV rays.…”

“…Italy has UNI 11842-2021 [75], which governs the test procedures for the mechanical characterization of bamboo culms. Greco et al [75] used this in their investigation of the photodegradation of bamboo in UV rays. The JIS is the Japanese International Standard, which was used by Bui et al [76] in their study on the effect of heat and oil treatment on the mechanical properties of bamboo.…”