title: Chemical modification of Dendrocalamus asper bamboo with citric acid and boron compounds: Effects on the physical-chemical, mechanical and thermal properties

authors: Gauss, Christian

abstract: The effect of environmentally friendly treatment using citric acid and boron compounds on the physical-chemical and mechanical properties and thermal degradation of D. asper bamboo was investigated. The chemical modification using citric acid reduced the moisture uptake of bamboo by 32%, the water absorption by 26%, and thickness and width swelling by 43% and 31%, respectively, in comparison with the reference. FTIR analysis revealed the effect of the esterification process with an increase of the carbonyl/hydroxyl absorbance ratio, which explains the reductions in water absorption and swelling. No significant change was identified on the cellulose crystallinity determined by XRD, with only a small increase of the boron-treated samples. TG/DSC measurements showed that boron compounds cause a reduction of weight loss and decrease the exothermic heat flow upon heating under synthetic air flow. However, the modification with citric acid caused slightly higher thermal degradation in the same conditions of testing, which was overcome by the addition of boron compounds in the treatment solution. Enhanced mechanical performance was observed on bamboo samples treated only with boron compounds, while samples chemically modified by citric acid presented no changes or a small increase in compression and bending properties. Nevertheless, fibre detachment and structural changes on hemicellulose/cellulose caused a small decrease in shear strength and a considerable decrease, about 30%, in tensile strength. The overall results provided an insightful understanding regarding the chemical modification of bamboo, revealing new possibilities of treatment for the improvements of dimensional and thermal stability without the use of hazardous chemicals.

text: Chemical modification of Dendrocalamus asper bamboo with citric acid and boron compounds: Effects on the physical-chemical, mechanical and thermal properties The effect of environmentally friendly treatment using citric acid and boron compounds on the physical-chemical and mechanical properties and thermal degradation of D. asper bamboo was investigated. The chemical modification using citric acid reduced the moisture uptake of bamboo by 32%, the water absorption by 26%, and thickness and width swelling by 43% and 31%, respectively, in comparison with the reference. FTIR analysis revealed the effect of the esterification process with an increase of the carbonyl/hydroxyl absorbance ratio, which explains the reductions in water absorption and swelling. No significant change was identified on the cellulose crystallinity determined by XRD, with only a small increase of the boron-treated samples. TG/DSC measurements showed that boron compounds cause a reduction of weight loss and decrease the exothermic heat flow upon heating under synthetic air flow. However, the modification with citric acid caused slightly higher thermal degradation in the same conditions of testing, which was overcome by the addition of boron compounds in the treatment solution. Enhanced mechanical performance was observed on bamboo samples treated only with boron compounds, while samples chemically modified by citric acid presented no changes or a small increase in compression and bending properties. Nevertheless, fibre detachment and structural changes on hemicellulose/cellulose caused a small decrease in shear strength and a considerable decrease, about 30%, in tensile strength. The overall results provided an insightful understanding regarding the chemical modification of bamboo, revealing new possibilities of treatment for the improvements of dimensional and thermal stability without the use of hazardous chemicals.

year: 2021

title: The potential for alternative materials in pavement construction

authors: Rogers, Darcy

abstract: The current materials used in pavement construction were developed in the 1930s but materials development has not kept pace with increasing traffic demands since this time. This report considers the potential for alternative materials that could offer greater performance in a pavement and meet current transport demands. In order to determine if there were opportunities for alternative materials, the performance of the current materials and associated design methodologies were reviewed. This review found that the current materials have extremely variable performance, with life spans ranging from 1 year to over 20 years and often fail due to insufficient strength in the current materials. Considering this, two key failure scenarios responsible for the majority of failures where identified: Scenario 1 – underlying material fails due to poor load spreading of the upper layers and Scenario 2 – where the upper layers fail through lack of strength or flexibility. By applying standard materials selection processes to consider materials that work under both of these scenarios it was found that wood, waste plastics and steel were options that could be considered as alternative pavement materials. It was found that three potential material configurations could be considered under each of these scenarios: homogenous materials, alternative asphalt matrices to bitumen and sandwich panels. The alternative materials outperformed the current pavement materials in terms of strength. Comparisons with the stiffness of the conventional pavement materials showed that the alternative materials were not as favourable in design methods that only consider the load spreading ability of the material (high stiffness). Field trials confirmed that materials with lower stiffness but much higher strength could offer greater performance than the current pavement materials and should be considered as alternative options to the current pavement materials.

text: The potential for alternative materials in pavement construction The current materials used in pavement construction were developed in the 1930s but materials development has not kept pace with increasing traffic demands since this time. This report considers the potential for alternative materials that could offer greater performance in a pavement and meet current transport demands. In order to determine if there were opportunities for alternative materials, the performance of the current materials and associated design methodologies were reviewed. This review found that the current materials have extremely variable performance, with life spans ranging from 1 year to over 20 years and often fail due to insufficient strength in the current materials. Considering this, two key failure scenarios responsible for the majority of failures where identified: Scenario 1 – underlying material fails due to poor load spreading of the upper layers and Scenario 2 – where the upper layers fail through lack of strength or flexibility. By applying standard materials selection processes to consider materials that work under both of these scenarios it was found that wood, waste plastics and steel were options that could be considered as alternative pavement materials. It was found that three potential material configurations could be considered under each of these scenarios: homogenous materials, alternative asphalt matrices to bitumen and sandwich panels. The alternative materials outperformed the current pavement materials in terms of strength. Comparisons with the stiffness of the conventional pavement materials showed that the alternative materials were not as favourable in design methods that only consider the load spreading ability of the material (high stiffness). Field trials confirmed that materials with lower stiffness but much higher strength could offer greater performance than the current pavement materials and should be considered as alternative options to the current pavement materials.

year: 2018

title: Cultural knowledge and identity for wellbeing and success: Trying to make the connections in the north of New Zealand.

authors: Hohepa, Margie Kahukura

subjects: New Zealand

abstract: This paper argues that secure cultural identity is essential to wellbeing and cultural identity is important to Māori youth participation and success. The roles of community and schools in developing secure cultural identity are increasingly complex, as both become increasingly more culturally and ethnically diverse in many parts of the world.
The paper discusses findings from student survey data from a 2 year project ‘Te Wehi Nui a Mamao: Maximising the potential of tribal marae and regional language among youth', which began in July 2008, supported by funding from New Zealand's Foundation of Research, Science and Technology. This project aims to strengthen the relevance of tribal marae and regional Maori language among Maori youth, which are identified as important to Māori cultural identity.
Inter-generational transfer of tribal marae knowledge and language is becoming more compromised. Many cultural values are defined on marae. Tribal leaders have long been concerned about disconnections between Māori youth and tribal marae, poor knowledge of regional dialect and the potential negative consequences for full participation in society. .It appears that Māori youth are disconnected from regional language dialects and marae knowledge now more than ever. Reconnecting Māori youth with these two sources of tribal identity is the key to the purpose of this project.

text: Cultural knowledge and identity for wellbeing and success: Trying to make the connections in the north of New Zealand. This paper argues that secure cultural identity is essential to wellbeing and cultural identity is important to Māori youth participation and success. The roles of community and schools in developing secure cultural identity are increasingly complex, as both become increasingly more culturally and ethnically diverse in many parts of the world.
The paper discusses findings from student survey data from a 2 year project ‘Te Wehi Nui a Mamao: Maximising the potential of tribal marae and regional language among youth', which began in July 2008, supported by funding from New Zealand's Foundation of Research, Science and Technology. This project aims to strengthen the relevance of tribal marae and regional Maori language among Maori youth, which are identified as important to Māori cultural identity.
Inter-generational transfer of tribal marae knowledge and language is becoming more compromised. Many cultural values are defined on marae. Tribal leaders have long been concerned about disconnections between Māori youth and tribal marae, poor knowledge of regional dialect and the potential negative consequences for full participation in society. .It appears that Māori youth are disconnected from regional language dialects and marae knowledge now more than ever. Reconnecting Māori youth with these two sources of tribal identity is the key to the purpose of this project.

year: 2010