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Data availability: Data will be made available on request. Copyright © 2023 The Authors. This paper investigates a vacuum heat treatment (VHT) technology at 160℃, 200℃ and 240℃ for 6–14 h to modify bamboo sawdust (BS) and then BS/cement composites for the development of low carbon construction materials. The hydration process, thermal stability, micro-morphology and crystallinity, and chemical and mechanical changes for both VHT BS and composites are examined by FTIR, TG-DTG, XRD and SEM analyses. The mechanism of improving the mechanical properties of modified BS on composite materials is further elaborated together with the physical and mechanical properties and durability. The results show that the flexural strength and compressive strength of the modified BS/cement composites after VHT at 200℃ for 10 h are increased by 61.2% and 13.8%, respectively, compared with those in the untreated group, and the composites have better durability in the modified group. VHT resulted in cellulose and hemicellulose degradation to certain degrees, lignin undergoes cross-linked condensation reaction and cellulose crystallinity increases. These changes reduce the number of BS hydrophilic groups and result in changes in BS microstructure and surface topography, providing favorable conditions for the bonding and interface development of BS/cement composites. The impact of BS/cement composites on the carbon footprint in the production stage was analyzed, showing that the carbon emissions of BS/cement composites after VHT were reduced by 5.7% compared with that of the corresponding OPC composites. Forestry Science and Technology Project of Fujian (KLB18007A); EU-NWE, Interreg IV B project ‘Grow2Build’.

Buildings contribute to 40% of total global energy consumption, which is responsible to 38% of greenhouse gas emissions. It is critical to enhance the energy efficiency of buildings to mitigate global warming. In the last decade, advances in thermal energy storage (TES) techniques using phase change material (PCM) have gained much attention among researchers, mainly to reduce energy consumption and to promote the use of renewable energy sources such as solar energy. PCM technology is one of the most promising technologies available for the development of high performance and energy-efficient buildings and, therefore, considered as one of the most effective and on-going fields of research. The main limitation of PCM is its leakage problem which limits its potential use in building construction and other applications such as TES and textiles, which can be overcome by employing nano-/micro-encapsulation technologies. This paper comprehensively overviews the nano-/micro-encapsulation technologies, which are mainly classified into three categories including physical, physiochemical and chemical methods, and the properties of microcapsules prepared. Among all encapsulation technologies available, the chemical method is commonly used since it offers the best technological approach in terms of encapsulation efficiency and better structural integrity of core material. There is a need to develop a method for the synthesis of nano-encapsulated PCMs to achieve enhanced structural stability and better fracture resistance and, thus, longer service life. The accumulated database of properties/performance of PCMs and synthesised nano-/micro-capsules from various techniques presented in the paper should serve as the most useful information for the production of nano-/micro-capsules with desirable characteristics for building construction application and further innovation of PCM technology.