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.

Rice husk is an agricultural by-product worldwide in large quantities available. This is a suitable biomass source for energy production. Compared to other agricultural by-products, the burned rice husk presents a high yield of ash (about 20%) mainly composed of silica that will be mostly amorphous when properly incinerated. Extensive research in the past three decades has allowed the introduction of rice husk ash (RHA) as a supplementary raw material in cement-based products, whereby significant improvements in strength and durability can be achieved, also contributing to ecological demands. This paper investigates the influences of two RHA admixtures on the physical and mechanical properties of bamboo-pulp–reinforced cement composites. These fibers suffer early degradation in the alkaline environment. RHA blending will reduce the ordinary Portland cement (OPC) content and can improve strength and density due to more effective particle packing, and significantly diminish alkalinity. The composites were produced in the laboratory by a method resembling the Hatschek process used by the fibrocement industry, with fixed reinforcement content and varying amounts of RHA. The results revealed that partial replacement of ordinary Portland cement by up to 30% of RHA had not impaired the mechanical behavior of the composites. Further, use of low-carbon-content RHA decreased porosity in the matrix and enhanced interfacial bonding of the composites. Since the deterioration of cellulose–cement composites is closely related to moisture movement and alkalinity, it is concluded that introduction of low-carbon content RHA can lead to improved durability performance of these composites.