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The chemical treatments applied to some lignocellulosic resources commonly used as building materials can influence their mechanical performance during service, and hence, this effect should be studied for structural safety reasons. In this piece of work, prismatic samples of Dendrocalamus asper bamboo were treated in a vacuum/pressure process with disodium octaborate tetrahydrate (DOT) solutions and the corresponding mechanical performance was compared with non-treated and water-treated samples. Full penetration of boron was achieved, with DOT retentions of 14.79 kg m −3 and 21.79 kg m −3 for 5% and 8% (wt/wt%) solutions, respectively. Dynamic modulus of elasticity (MOE), static MOE, and compressive modulus of elasticity of the material, with values between 23.3-24.0, 15.9-16.2, and 26.2-27.2 GPa, respectively, were statistically equivalent for all the analyzed treatment conditions. However, a significant influence of the treatment could be observed on the specific compressive strength of bamboo, showing an increase of 35.3% for the 5% solution and 30.6% for the 8% solution. Although without statistical difference among the treatments, similar behavior was observed on the specific modulus of rupture (MOR) under flexural loading, with an increase of up to 10.1% in relation to the reference for the treated samples. The results achieved in the present study from nondestructive excitation pulse, three-point bending, and axial compression tests demonstrated that mechanical behavior of bamboo was preserved or even enhanced by the proposed treatments based on disodium octaborate tetrahydrate.

Densification processes are used to improve the mechanical and physical properties of lignocellulose materials by either collapsing the cell cavities or by filling up the pores, consequently reducing the void volume fraction. This paper focuses on an extensive review of bamboo densification process, which is achieved by compressing the material in the direction perpendicular to the fibers using mainly two different techniques: an open system, thermo-mechanical (TM), or a closed system, viscoelastic-thermal-compression (VTC). The main aim of bamboo densification is to decrease its heterogeneity, as well as to improve its mechanical and physical performance. In addition, densification may occur during the manufacturing of bamboo products in which hot-pressing processes are used to mold bamboo panels. There are over 1600 publications about bamboo, concentrated in the recent decade, mainly about engineered materials. Although several papers regarding bamboo and wood densification are available, very few studies have comprehensively investigated the densification process solely through compression of natural bamboo culms. According to the literature, applying a combination of compression of 6–12 MPa at temperatures between 120–170 °C for 8–20 min can produce materials with higher strength in comparison to the mechanical properties of natural bamboo. The majority of research on bamboo densification indicates that the modified material results in improved properties in terms of density, hardness, bending strength, stiffness, and durability. This paper provides a review that consolidates knowledge on the concept of bamboo culm densification, discusses the roles of parameters that control the process, ascertains the best practice, and finally determines gaps in this field of knowledge.