绿色施工理念下的建筑垃圾治理研究

建筑行业属于高能耗产业,施工中会产生大量的建筑垃圾,如果不采取有效的管理措施,那么必然无法保证建筑行业的持续发展,同时也不利于生态环境的保护.在这种背景下,绿色施工理念应运而生并且受到广泛的认可.为了进一步将绿色施工理念应用于建筑行业,提高建筑垃圾治理能力,相关工作人员需要明确建筑垃圾的概念和危害,分析当前建筑垃圾处理...     

Investigations into lightweight solutions for epoxy composite fire property improvement

Abstract

The aim is to study methods to improve the fire properties of carbon fibre reinforced epoxy composites with interlayers without compromising structural performance, i.e. using a carbon fibre veil with expandable graphite, an intrinsically flame retardant thermoplastic film or a carbon fibre reinforced thermoplastic (CFTP) layer. The CFTP layer seems the most promising, with a significant improvement in fire properties as determined with cone calorimetry, while the mechanical performance of the modified composite appears unaffected.     

Insulation failure of lightweight composite sandwich panels exposed to flame

A critical consideration for the serviceability of composite sandwich panels is their thermal behaviour during fire incidents. This research aims to observe the thermal performance and investigate the insulation failure of the lightweight concrete sandwich panels (LCSPs) in non-load bearing wall systems. Six standard one-sided coupling fire tests on LCSPs in accordance with Australian standard AS 1530.4 were conducted via an electrical furnace; measured by thermocouples and a thermal camera, to assess the insulation capacity and their behaviour during fire events. The results indicated that the sandwich panels have insulation capacity for 75 to 110 minutes depending on the thickness and density. The bowing of the panels due to the expansion of the exposed steel shield and the consequent de-bonding and cracking of concrete was one of the primary reasons of insulation failure. Additionally, this bowing led to the opening of the joints between the panels, which could allow the heat flows towards the unexposed surface. Moreover, the propagation of accelerated drying shrinkage cracks in the restrained concrete core was another reason for the failure. Lastly, the results suggested the benefits of increasing the thickness and density on thermal performance and insulation failure of the composite sandwich panels.     

Design,manufacture, and test of lightweight composite sandwich helmets

Abstract

This paper summarises work undertaken on the design, manufacturing development, and impact testing of a lightweight composite aircrew helmet. Full details are given on the double diaphragm forming process, developed at DERA, which has been extensively used to manufacture the complex, doubly curved layers that form the final helmet assembly. Manufacturing options for the development of a ‘form fitting’ foam liner are also included, as are developments in the foam liner press moulding processes.

Results from an extensive impact test programme conducted on fully assembled shell samples are provided, illustrating good energy management during test. Some redundant material was apparent from the results, hence further mass reduction is possible. Modification of the layer deformation sequence is also required. However the sandwich shells met all impact test requirements. Correlation of the impact test data and helmet damage cross- sections has allowed recommendations to be made regarding improved design and manufacture of the layered construction. Predictions based on these improvements show the final helmet mass should be ～750 g, excluding breathing systems and communications.     

绿色施工理念下的建筑工程管理模式创新思考

在绿色环保建筑项目工程的管理实践中,必须要运用科学的方式,这样才可以高效地节约资源,更好地让建筑公司完成节约成本的目标,优化大众的生活品质,继而更好地帮助城市化进程实施.可是,现阶段我们国家的绿色建筑管治思想还不完善,绿色环保建筑管治方法与管治手段还没有很成熟,绿色环保建筑管理实践中还不具有切实可行的制度与准则.基于此...     

轻量化复合材料车体粘接接头设计及试验验证

以轻量化复合材料车体为主体,介绍了粘接技术在轨道车辆新材料、新工艺、新结构中的应用,并阐述粘接结构设计、胶粘剂选型及试验验证工作。     

A hybrid bondline concept for bonded composite joints

Based on the experience in the past and the occurrence of in-service damages, the authorities restrict today the application of adhesive bonding of composite structures for aircraft applications. However, certification limitations can be overcome if occurring disbonds within a bond are stopped by implemented design features, so-called disbond stopping features. Consequently, a novel bondline architecture for bonded composite joints is proposed. By implementing a distinct rather ductile thermoplastic phase, a physical barrier for growing disbonds is obtained and thus a fail-safe design, respectively. Moreover, the joint is established by using two different joining technologies, namely adhesive bonding and thermoset composite welding. A sophisticated manufacturing technique is developed for the hybrid bondline concept to achieve a high strength joint. The joint׳s quality is examined by means of several analytical methods like microsections, scanning electron microscopy (SEM), and energy-dispersive X-Ray (EDX) analysis. Additionally, the mechanical performance is evaluated by static Double Cantilever Beam (DCB) and Single Lap Shear (SLS) tests.     

A sustainable construction of an efficient lightweight microwave absorber from polymeric sponge

A sustainable method is proposed to prepare carbon-sponge/CoNi composites from sponge to sponge/CoNi followed by sintering. All CoNi nanoparticles (NPs) are uniformly anchored on the carbon-sponge, and the as-prepared products are stable under ultrasound treatment, implying the CoNi NPs are grown in situ on the carbon-sponge with a strong interaction. The electromagnetic microwave absorption (EMWA) performances of the carbon-sponge/CoNi are properly adjusted by controlling the calcination temperature. The carbon-sponge/CoNi obtained at 800 °C (C800) displayed excellent EMWA performances; the minimum reflection loss (RL_min) was −39.7 dB, and the effective absorption bandwidth (EAB, RL ≤ −10 dB) was more than 5.12 GHz (≥12.88 GHz) with a thin layer thickness of 1.5 mm. The superior EMWA performances of carbon-sponge/CoNi composites benefit from the synergistic effect of magnetic CoNi and the dielectric carbon-sponge. This work can pave a new road for designing lightweight and high-performance carbon composites from sustainable materials.     

Adhesive-bonded steel/concrete composite construction

The development of a new form of roadway deck for bridges is described. This consists of a concrete core bonded to a steel soffit plate using epoxy resin adhesive. The durability of structural joints made with a number of adhesives and with steel, concrete, and aluminium adherends is being investigated. There is a marked difference in resistance to damp conditions between different grades of epoxy resin. A search for further potential structural applications continues.     

Fire resistance performance of composite coating with geopolymer-based bio-fillers for lightweight panel application

Structural insulated panel (SIP) requires fire-resistant coating due to its substrate having low melting point. This article presents the effect of filler and binder on fire resistance, thermal stability, and surface morphology of composite coating. Palm oil clinker filler-type coatings made using ordinary Portland cement (OPC:POC), calcium aluminate cement (CAC:POC), and alkali-activated geopolymer (GP:POC) binders were analyzed. GP:POC was then compared to other geopolymer-binder type coating with different fillers such as rice husk ash (GP:RHA), metakaolin (GP:MK), and hybrid filler of POC and RHA (GP:POC-RHA). It was found that geopolymer binder-type specimens have better fire-resistance due to low thermal conductivity caused by their porous microstructure and intumescence behavior. Then, the coating formulation was optimized in terms of thickness, alkaline activator ratio and curing regime which produced GP:RHA' that lasted almost 2 hours during flame exposure test. This article concludes that geopolymer-binder type composite is a plausible fire-resistant coating for SIP.     

轻质复合材料高压容器的研究和结构设计

轻质复合材料高压容器的应用越来越广泛,随着氢能和天然气等清洁燃料在汽车中的应用,其轻量化和安全性的研究显得特别重要。主要进行高压储氢容器的研究与结构设计,该结构采用高强度铝合金内胆、外缠绕高强度纤维复合材料构成压力容器,它具有质量轻、防渗漏、耐压能力强等特点;通过提高储氢压力和减轻容器重量来提高储氢密度,储氢密度可达到5%以上;设计中改进了纤维缠绕的预应力分布,在操作时降低了铝内胆的平均应力,提高了容器的抗疲劳性能和综合安全性能。     

Continuous electrodeposition for lightweight, highly conducting and strong carbon nanotube-copper composite fibers

Carbon nanotube (CNT) fiber is a promising candidate for lightweight cables. The introduction of metal particles on a CNT fiber can effectively improve its electrical conductivity. However, the decrease in strength is observed in CNT-metal composite fibers. Here we demonstrate a continuous process, which combines fiber spinning, CNT anodization and metal deposition, to fabricate lightweight and high-strength CNT-Cu fibers with metal-like conductivities. The composite fiber with anodized CNTs exhibits a conductivity of 4.08 × 10(4)-1.84 × 10(5) S cm(-1) and a mass density of 1.87-3.08 g cm(-3), as the Cu thickness is changed from 1 to 3 μm. It can be 600-811 MPa in strength, as strong as the un-anodized pure CNT fiber (656 MPa). We also find that during the tensile tests there are slips between the inner CNTs and the outer Cu layer, leading to the drops in electrical conductivity. Therefore, there is an effective fiber strength before which the Cu layer is robust. Due to the improved interfacial bonding between the Cu layer and the anodized CNT surfaces, such effective strength is still high, up to 490-570 MPa.     

Durability of a lightweight construction material made with dune sand and expanded polystyrene

The partial/total substitution of ordinary aggregates by other unused local materials in order to produce new lightweight concretes/mortars is an interesting alternative that can solve technical, economical and environmental problems. On the other hand, the replacement of cement by other binders in the elaboration of concretes and mortars can also provide other properties and benefits more important and more interesting. In this context, previous works have been undertaken and have shown the possibility and the effectiveness of the use of expanded polystyrene aggregates and dune sands on the physicomechanical properties of plaster mortars, especially in term of lightness and thermal insulation. Our current concern is to know: how this composite will behave in certain aggressive environments. Therefore, the main objective of the present work is to study the effect of some chemical environments on the behaviour of a plaster mortar based on dune sands and expanded polystyrene beads. For this study, three different environments have been envisaged: demineralised water (as reference), sulphuric acid solution and magnesium sulphate solution. The obtained results showed that although the surface of the studied samples seems to be degraded, in their interior, the material appears more homogeneous and compact with relatively a good adhesion sand/plaster and EPS/plaster. The presence of the acid or the sulphate in water does not increase the water effect; besides, the acid considerably improves its effect in compression.     

Dynamic mechanical studies of a highly filled composite structure: A lightweight coated paper

A composite sandwich structure, consisting of a paper sheet as a middle layer and two porous coating layers of a highly filled acrylate–styrene–butadiene copolymer, has been studied by means of a dynamic mechanical test in torsion. Stiffness and mechanical damping, tan δ, were recorded over the temperature region where the latex polymer exhibits a glass transition. The mechanical damping decreases with increasing filler content in the coating. Variations in the thickness of the coating layers did not influence the mechanical damping. The glass transition temperature of the latex polymer increases with increasing volume fraction of filler at high filler contents as an effect of filler–matrix interaction. The outer layers partly penetrate into the middle layer, as indicated by thickness measurements on the coated paper. A theoretical comparison of the peak heights of the mechanical damping using lamination theory shows a discrepancy in the experimental results. If penetration of the outer layer is allowed for, i.e., if using a thicker outer layer of the composite in the calculations, a favorable correlation between the theoretical and the experimental results is obtained. © 1993 John Wiley & Sons, Inc.