Assessing multiple criteria for the optimal location of a construction and demolition waste management facility

Construction industry is the most significant fields on a global scale, with respect to its economic, technological, and environmental impact. Its rapid growth over the last decades has resulted in an enormous increase of the produced construction and demolition waste, thus provoking a considerable burden on the environment. The proposed methodological framework is aiming towards optimal location of units of alternative construction and demolition waste management and it is following the path of multicriteria analysis. For the problem under study, ELECTRE III technique is adopted. The decision process presented requires the adoption of a number of logical steps mainly, clarification of the decision criteria for selecting the optimal location (economical, environmental and social), the definition of their relative significance and data assembly. The approach allows a robust parameter analysis in order to evaluate and compare in detail all available alternatives. On top of that, sensitivity analysis is also available, since parameter values in real life applications originate from estimations which are sometimes more or less reliable. This paper presents an effort to interlace local acceptance, financial viability and level of environmental quality which represents a vital issue for the particular waste stream’s management efficiency. The methodology is implemented and demonstrated for the case of the Region of Central Macedonia, Greece and can be employed either by private investors or public authorities in other areas internationally.     

A study conducted to reduce construction waste generation in Turkey

Waste occurs within the lifecycle of buildings, during the construction, modification and demolition phases. These construction wastes become serious environmental problems in many countries and in Turkey. However, no net data regarding the amount of construction wastes exist in Turkey. During its period of usage, frequent interior modifications are made for various reasons, particularly true for residences in Turkey, thus generating construction wastes. The primary environmental target regarding this subject should be the prevention and reduction of construction waste generation. The aim of this study is to provide suggestions regarding the prevention/reduction of waste generated due to modifications done for various purposes in residences in Turkey. To this end, a survey of homeowners in Istanbul was conducted to determine the nature and purpose of modification work done in residences. In order to come up with solutions towards reducing the construction waste generation, it is vital that these reasons are known. In light of the causes determined, suggestions for solving the problems have been developed.     

The use of fine portions from construction and demolition waste for expansive soil stabilization: A review

Construction and demolition waste (CDW) are the largest waste products in the world today and competes as a viable recycled additive material in place of natural aggregates. Due to the increase in compressive strength of different mix proportions of CDW, it is also considered for reuse in concrete and subbase construction. This study shows the effect of CDW in expansive soil stabilization. The chemical and mechanical properties of these materials have shown that they are capable of developing compressive strength properties for replacement of cement with significant reduction in carbon emission. The inherent compositional properties of recycled CDW compared in this review suggests that CDW have good filler properties in highly expansive soils. Mixtures of crushed brick and recycled aggregates characterised based on chemical properties of different replacement ratios suggests that CDW of good-quality aggregates reduces swell potential of expansive soils and increased mechanical strength in pavement construction.     

Three methods for verifying and validating the simulation of a construction operation

A simulation model must be verified to confirm that it describes correctly its intended real world process under study; moreover, the simulation results obtained must be a valid representation of the process. This study presents three activity-based white-box methods for assisting a user in verifying and validating construction simulations. The first method reports a simulation by listing all activities in the chronological order of their executions, so that a user can contrast the simulated progress against the actual progress in the real world. The second method summarizes the operating counts and mean durations of all activities over the simulated time period, to enable a user to evaluate whether all activities have been executed correctly during simulation. The third method generates an activity cycle report for any selected resource entity, so that a user can examine whether the entity is moving in the correct logical and chronological order during simulation. The three methods can be used jointly to debug a simulation model, so as to confirm that the simulation is correctly conducted and the obtained results are valid. The three methods are implemented in a simulation system in the form of corresponding reports. A concreting process is employed to illustrate these methods.     

Model based prognosis of contaminant leaching for reuse of demolition waste in construction projects

In this study, groundwater contamination from recycled demolitian waste in road constructions is assessed using predictions of leachate concentrations. Numerical transport simulations are performed for three scenarios (a parking lot, a noise protection barrier, and road), and using a number of characteristic subsoils of Germany, to estimate the breakthrough of different contaminant classes at the groundwater table. Conservative tracer breakthrough times (BTT) primarily depend on subsoil hydraulic properties, for organic pollutants KOC and subsoil OC are the controlling parameters. Significant concentration reductions from dispersion only occur when source concentrations decrease prior to contaminant breakthrough. If source concentrations remain high for long periods relative to peak BTT, concentration breakthrough is undamped. Accounting for biodegradation reduces breakthrough concentrations significantly. For the “noise protection barrier” and “road” scenarios, capillary barrier effects cause the seepage water to partially bypass the recycling material. Accounting for this bypass flow and spatial averaging across the constructions reduces concentrations by about 30–40?%.     

Assessment of construction processes and innovations through simulation

The objectives of this research are to represent construction activities accurately, and to provide a means for assessing the impacts from using innovations. The research approach is the detailed characterization of construction processes, and the development of system and material specific dynamic process simulation models. The ongoing research program is developing a set of specific models, based on extensive empirical data, to enable the accurate modelling of all of the construction processes for a complete facility construction project. A specific process model, glass/metal curtainwall erection, demonstrates the approach, with an analysis of the impacts from a related innovation.     

U形下穿道上跨桥拆除施工技术

以重庆国际会展中心二期市政工程为工程背景,介绍了＂U＂形下穿道上跨桥拆除施工过程及工艺,通过施工技术措施的实施,确保了施工、进度、安全要求,为类似工程积累了宝贵经验。     

Employee perceptions of the solid waste management system operating in a large Australian contracting organization: implications for company policy implementation

A survey of employees' perceptions of a large contracting firm's waste management system was conducted. Results were factor analysed and an eight-factor model of the waste management climate was identified. Perceptions were found to differ between employee groupings. Managerial staff had a less positive perception of the waste management climate than did site workers. Qualitative interview data were analysed using a content analysis approach. Managers were found to perceive environmental issues as being less important than cost, time or quality objectives. Construction workers believed environmental issues to be of greater importance than these other objectives. Differences in perceptions of managers and site workers have implications for the implementation of any company waste management policy. There is a need to involve workers in identifying waste management solutions, to provide more information to all employees about practical aspects of waste management, and for managers visibly to demonstrate commitment to waste management policy objectives.     

国内外建筑垃圾资源化现状及发展趋势

从政策法规和工艺技术两方面综述了国内外建筑垃圾资源化的现状,并分析其发展趋势,阐明了我国推行建筑垃圾资源化的重要性与必要性。     

浅谈桥梁拆除施工技术控制方法

以安徽省合宁高速公路南淝河大桥拆除工程为倒,介绍了桥梁拆除施工技术控制方法及施工工艺,并阐述了施工过程中的关键控制点及观测监控措施,以确保桥梁拆除施工安全、文明、经济。     

Laboratory evaluation of recycled construction and demolition waste for pavements

The wide production of construction and demolition waste and its illegal deposition are serious current problems in Brazil. This research proposes to evaluate the feasibility of using aggregate from recycled construction and demolition waste (RCDW) in pavement applications. A laboratory program was conducted by geotechnical characterization, bearing capacity and repeated load triaxial tests. The results show that the composition and the compactive effort influence on the physical characteristics of the RCDW aggregate. The compaction process has promoted a partial crushing and breakage of RCDW particles, changing the grain-size distribution and increasing the percentage of cubic grains. This physical change contributes to a better densification of the RCDW aggregate and consequently an improvement in bearing capacity, resilient modulus and resistance to permanent deformation. The results have shown that the RCDW aggregate may be utilized as coarse base and sub-base layer for low-volume roads.     

建筑交易制度探析

阐述了交易制度的定义与内涵,探讨了交易制度的功能,重点从交易费用的角度分析了交易制度的合理性,根据我国传统工程交易模式DBB的缺点,提出了一些新的工程交易模式,对节省交易费用和提高工程效率具有重要意义。     

在拆除既有线道岔并联通线路施工中的QC应用

以某改造工程为例,介绍了拆除既有线道岔并联通线路施工中QC小组活动的应用,从现状调查、目标确定、原因分析、对策实施、效果检查等方面作了具体叙述,通过QC小组的应用,解决了拆除道岔联通线路的难题。     

钢筋混凝土墩部分爆破拆除

以某桥墩拆除工程为例,通过拆除体不同区域的爆破,在不损坏保留部分并保证安全的前提下,成功地将钢筋混凝土墩身部分爆破拆除,详细总结归纳了爆破拆除的技术要点和经验,对今后同类工程具有一定指导意义。     

顶推法拆除连续梁桥导梁的设计及施工

结合佛开高速改扩建工程实例,介绍了顶推法拆除旧北江大桥主桥的方法,着重对顶推法施工中导梁的设计、施工及拼装方案进行了研究,并阐述了导梁的静载试验技术,为顺利进行主桥顶推过程提供了科学依据。     

活性胶结料对建筑垃圾小型空心砌块强度影响的研究

本文对建筑垃圾小型空心砌块的原材料进行简介,分析了活性胶结料的种类与作用,通过实验,找出了粉煤灰对强度的影响因素,提出了解决强度稳定的技术路径。     

当前拆迁补偿中存在的问题及其完善

阐述了拆迁补偿这一问题提出的背景及意义,针对当前拆迁补偿中存在的问题进行了详细分析,并提出了城市房屋拆迁政策进一步完善的建议及措施,从而为立法提供了依据,以保障社会主义市场经济法律体系的日趋完善。     

Continuous and combined event-process models for simulating pipeline construction

A continuous model and a combined event-process discrete model are developed by employing the Slam II general purpose simulation language. The continuous model addressed the on-going progress of the construction process on a higher level; and the combined event-process discrete model describes the pipeline construction on the operational level. Resource sharing and related issues also are investigated in the two models through an actual gas line project adopted for the purpose of this research. A comparison of the two models provides insights into the modelling approaches. It is concluded that the combined event-process model is more flexible and more powerful for modelling complex construction operations than the continuous model, but at the price of requiring a better understanding of the actual operations and more detailed information.     

工程车辆电液自动调平系统

介绍一种适用于工程车辆的电液自动调平系统，着重分析其工作原理及调平传感器的结构和液压系统的设计。     

对运城市公共资源交易平台建设的思考与建议

论述了运城市公共资源交易平台建设的背景,对建立公共资源交易平台主要做法进行了分析,包括抓体制创新与机制建设、抓环境优化与礼仪培训、抓创新敢为与科技为先等内容,并结合公共资源交易平台建设的体会心得,给出了几点建设建议。