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The production of ordinary Portland cement (OPC) is responsible for a significant part of global CO2 emission. For decades, the raw material and high burn temperature (up to 1500 °C) for OPC production have not been changed to reduce the CO2 emission significantly. In order to reduce the CO2 emission for cement production, two types of recycled cements (RC-450 °C and RC-800 °C) were produced in this study. It is hoped that the potential application of recycled cement could help to mitigate the CO2 emission in cement production. The application of recycled cement could significantly reduce the environmental impacts caused by the landfills of demolished waste concretes. The recycled cements RC-450 °C and RC-800 °C were produced through burning waste old OPC pastes at 450 °C and 800 °C respectively and then grinding into powder through a ball mill. The CO2 emissions from producing OPC, RC-450 °C and RC-800 °C were calculated and compared through considering the CO2 emissions from both fuel burning and the clinker materials. Compared to the production process of OPC, the production of RC-450 °C can reduce 94% of CO2 emission. By mixing with water, an additional 4% CO2 by weight of RC-450 °C can be captured in the RC-450 °C paste through the formation of calcium carboaluminate and additional calcite. RC-450 °C showed lower CO2 emission but a higher strength of paste than RC-800 °C. Besides, RC-450 °C paste was found to have a similar strength as the OPC paste, and this suggests that the RC-450 °C could be used to totally replace OPC.

A manufacturing process with the capability to integrate electronics into 3D structures is of great importance to the development of next-generation miniaturised devices. In this study, Selective Laser Melting (SLM) was used to process copper/high-density-polyethylene (HDPE) powder mixtures to build conductive tracks in a 3D circuit system. The effects of copper/HDPE volume ratio, laser input power and scanning speed on the resistivity of CO2 laser processed tracks were investigated. The resistivity of the tracks decreased from 26.6 ± 0.6 × 10−4 Ωcm to 1.9 ± 0.1 × 10−4 Ωcm as the copper volume ratio increased from 30% to 60%. However, further increasing the copper ratio to 100% resulted in poor conductivity. The lowest resistivity was achieved with an input power of 20 W and scanning speed of 80 mm/s. Additionally, processing using single-track-scanning and raster-scanning programs was compared; the overall energy distribution on the surface was more uniform using a raster-scanning program, which further reduced the resistivity to 0.35 ± 0.04 × 10−4 Ωcm. Based on the results, a 3D multi-layered circuit system was manufactured with the HDPE as the substrate/matrix material and copper/HDPE mixture as the conductive-track material. This circuit system was successfully manufactured, demonstrating the possibility of using SLM technology to manufacture dissimilar materials towards 3D electronic applications.

Improving building energy efficiency and decreasing building energy consumption through monitoring of heating, ventilation and air conditioning (HVAC) and heat recovery systems are becoming increasingly significant due to global energy crisis and carbon emission. Therefore, evaluation on building energy efficiency and energy conservation is extremely necessary. In the present work, energy conservation performance of one low-energy school building will be intensively investigated based on more than three-year measurement results from the monitoring system with sensor network. Heat recovery efficiency and new energy conservation parameter were analytically modeled, taking the building mechanical ventilation network into account. Following that, building energy performance has been experimentally investigated concerning the effects of mechanical ventilation rates, outdoor temperature and the efficiency of the heat recovery facility. Subsequent energy performance analysis demonstrates that building energy demands for ventilation and winter heating could be decreased with the enhancement of heat recovery efficiency of the ventilation facility, and the energy conservation ratio of the air conditioning unit increases with the temperature of supply fresh air. Diverse situations of energy conservation ratio and heat recovery efficiency have been detailedly correlated according to measurement results.

Acrylonitrile butadiene styrene (ABS) specimens fabricated by fused filament fabrication (FFF) were post treated by acetone, ethyl acetate and their mixed vapour. The effect of different chemical vapour, exposure time and building orientation on the surface roughness, tensile strength, dimension and weight stability of the ABS specimens were investigated before and after treatment. The results demonstrated that all chemical vapours were capable of improving the surface coarseness of ABS specimens. The tensile strength of specimens treated with the acetone or the mixed vapour decreased with increasing the exposure time. Surprisingly, it did not change for specimens treated with the ethyl acetate vapour when the exposure time reached 30 min. The deviations of length and width of specimens after chemical vapour treatment were lower than 5 %, irrespective of the building orientations. However, the deviations of thickness were high (up to 25 %). The weight of specimens after treatment increased with prolonging the exposure time due to the absorption of the chemical vapours.

The correlation between MWCNT aspect ratio and the quasi-static and dynamic mechanical properties of composites of MWCNTs and PMMA was studied for relatively long MWCNT lengths, in the range 0.3 mm to 5 mm (aspect ratios up to 5 × 105) and at low loading (0.15 wt%). The height of the MWCNTs prepared were modulated by controlling the amount of water vapour introduced in the reactor limiting Ostwald ripening of the catalyst, the formation of amorphous carbon and any increase in CNT diameter. The Tg of PMMA increased by up to 4 °C on addition of the longest tubes as they have the ability to form physical junctions with the polymer chains which lead to enhanced PMMA-MWCNTs interactions and increased mechanical properties, Young's modulus by 20% on addition of 5 mm long MWCNTs. Predictions of the Young's modulus of the composites of PMMA and MWCNT with the Mori-Tanaka theory show that future micromechanical models should account for MWCNT agglomeration and polymer-nanotube interactions as a function of CNT length.

Shape stabilised phase change materials (SSPCMs) based on a high density poly(ethylene)(hv-HDPE) with high (H-PW, Tm = 56–58 °C) and low (L-PW, Tm = 18–23 °C) melting point paraffin waxes were readily prepared using twin-screw extrusion. The thermo-physical properties of these materials were assessed using a combination of techniques and their suitability for latent heat thermal energy storage (LHTES) assessed. The melt processing temperature (160 °C) of the HDPE used was well below the onset of thermal decomposition of H-PW (220 °C), but above that for L-PW (130 °C), although the decomposition process extended over a range of 120 °C and the residence time of L-PW in the extruder was