Densification of bamboo: State of the art

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

Experimental analysis of Pressed Adobe Blocks reinforced with Hibiscus cannabinus fibers

WOS:000331424400009International audienceThere is an intense on-going search for less polluting materials and technologies, which consume little energy in their production, construction and/or utilization. Attention of the researchers has turned to materials, which found applications in engineering in pre-industrial times: local vegetable fibers and earth composites are one of the promising materials. This paper presents the results of an investigation in establishing the physical and mechanical properties of Hibiscus cannabinus fibers which have been used in the fabrication of Pressed Adobe Blocks (PABs). The PABs have been reinforced with 0.2-0.8 wt.% of 30 mm and 60 mm lengths of H. cannabinus fibers. The microstructural characteristics of the PABs composites were investigated using X-ray diffraction (XRD), thermal gravimetric analyses (TGA), scanning electronic microscopy (SEM) and video microscopy. It was established that the addition with 0.2-0.6 wt.% of 30 mm long fibers reduced the dimensions of the pores in the PABs with the improvement of their mechanical properties. However, the addition of 0.8 wt.% of 60 mm fibers had negative effects on the compressive strength. The elaborated Pressed Adobe Blocks specimens were suitable as building material with contribution for thermal comfort. (C) 2013 Elsevier Ltd. All rights reserved

Resposta à flexão e análise de tenacidade de argamassas reforçadas com fibra de Curauá

O desenvolvimento e comercialização de materiais compósitos produzidos a partir de fibras naturais são considerados extremamente importante, uma vez que essas fibras reduzirão a dependência dos materiais produzidos com recursos não renováveis. Dentre essas fibras naturais destaca-se a fibra do curauá, sua utilização na produção de compósitos melhora de forma notável as propriedades do conjunto fibra matriz, logo o presente artigo objetiva estudar as propriedades mecânicas de compósitos reforçados com fibra de curauá, em especial sua resistência à flexão e tenacidade. Para isso foram confeccionadas cinco famílias de argamassas, uma de referência sem utilização da fibra e as outras quatro reforçada com fibra variando o comprimento da fibra e sua fração volumétrica. Verificou-se que a fibra do curauá ao ser adicionada em matriz cimentícia melhora suas propriedades mecânicas comparada a um compósito não reforçado com fibra, sua deformação, resistência à flexão e tenacidade são melhoradas

The interaction between cross-sectional distortion and the fatigue behaviour of box girder corner welds

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Propriedades físicas e mecânicas do colmo inteiro do bambu da espécie Guadua angustifolia

Este trabalho apresenta os resultados de recentes pesquisas sobre o bambu da espécie Guadua angustifolia, realizadas na Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), no qual foram determinadas as propriedades físicas, mecânicas e meso-estruturais dos colmos inteiros. O principal objetivo deste estudo é apresentar, aos profissionais, a possibilidade de usarem o bambu como elemento estrutural. Os resultados apresentados permitirão aos engenheiros e arquitetos selecionar, em seus projetos, as dimensões requeridas, como diâmetro, espessura e distância internodal, tensões de flexão, tensões máximas de tração, compressão e cisalhamento. Estão apresentadas a variação da fração volumétrica ao longo da espessura do bambu e suas propriedades mecânicas ao longo do comprimento total do colmo estudado

Application of Small Diameter Bamboos in Architecture

Having built several constructions with widely used bamboo species in Ubatuba-Brazil during the years 2004-2006, it was found that one of the main problems in the construction of bamboo structures was the local accessibility of these species. The unavailability of these species leads to higher costs for transportation and to higher environmental impacts. These widely used bamboo species typically have diameters ranging from 12 to 20 cm when used in constructions. Locally available bamboo species have smaller diameters, ranging from 4 to 8 cm, such as Bambusa Tuldoides (Taquaral) or Phyllostachys Aurea (Mirim). These are however rarely used in construction. The main objective of this paper is to present several experimental case studies using small diameter bamboos in order to share the insights gained to construct with such small diameter bamboo species.status: publishe