Over the last decade, the concept of the circular economy has regained attention, especially related to efforts to achieve a more sustainable society. The ‘revival’ of the circular economy has been accompanied by controversies and confusions across different actors in science and practice. With this article we attempt at contributing to advanced clarity in the field and providing a heuristic that is useful in practice. Initially, we take a focus on the historical development of the concept of circular economy and value retention options (ROs) for products and materials aiming for increased circularity. We propose to distinguish three phases in the evolution of the circular economy and argue that the concept – in its dominant framing – is not as new as frequently claimed. Having established this background knowledge, we give insights into ‘how far we are’ globally, with respect to the implementation of circularity, arguing that high levels of circularity have already been reached in different parts of the globe with regard to longer loop value retention options, such as energy recovery and recycling. Subsequently, we show that the confusion surrounding the circular economy is more far reaching. We summarize the divergent perspectives on retention options and unite the most common views a 10R typology. From our analyses, we conclude that policymakers and businesses should focus their efforts on realization of the more desirable, shorter loop retention options, like remanufacturing, refurbishing and repurposing – yet with a view on feasibility and overall system effects. Scholars, on the other hand, should assist the parties contributing to an increased circular economy in practice by taking up a more active role in attaining consensus in conceptualizing the circular economy.

The circular economy: New or Refurbished as CE 3.0? — Exploring Controversies in the Conceptualization of the Circular Economy through a Focus on History and Resource Value Retention Options

Copper-mine tailings are the residual products after the extraction of precious copper metal from copper ores, and their storage can create numerous environmental problems Many researchers have used copper-mine tailings for the preparation of geopolymers This paper studies the enhancement of the cementitious activity of copper-mine tailings in geopolymer systems First, copper-mine tailings are activated through mechanical grinding activation Then, the mechanically activated copper-mine tailings are further processed through thermal activation and alkaline-roasting activation The cementitious activity index of copper-mine tailings is characterized through the degree of leaching concentration of Si and Al It was observed that the Si and Al leaching concentration of mechanically activated tailings was increased by 2603% and 9333%, respectively The concentration of Si and Al was increased by 5419% and 11992%, respectively For alkaline-roasting activation, roasting time, temperature and the mass ratio of copper-mine tailings to NaOH (C/N ratio) were evaluated through orthogonal tests, and the best condition for activation was 120 min at 600 °C with a C/N ratio of 5:1 In this study, scanning electron microscopy (SEM), X-ray diffraction (XRD) and infra-red (IR) analysis show that mechanical, thermal and alkaline-roasting activation could be used to improve the cementitious activity index of copper-mine tailings

Enhancement Experiment on Cementitious Activity of Copper-Mine Tailings in a Geopolymer System

This article presents an extensive overview of state of the art in design and testing of design for deconstruction concrete connections for concrete elements by reviewing and discussing the results...

Experimental and numerical studies on design for deconstruction concrete connections: An overview:

Construction equipment planning and selection plays crucial role for the success of construction firms.Inadequate manual processes of equipmentplanning and selection and the subjective decisions of equipment managers usually result in major losses in construction firms. An indispensable item of resources, it produces output at accelerated speed, enables completion of task in limited time. Equipment saves manpower, which is becoming costly and more demanding day by day. Equipment improves quality, productivity and safety. Construction equipment planning aims at identifying construction equipment for executing project tasks, assessing equipment performance capability, forecasting date wise requirement of number and type of equipment and finally participating in the selection of equipment to be acquired. To derive full benefits from the equipment, there should be proper selection and good planning of its operations. This paper deals with the planning and selection procedure for equipment adopted by a company to achieve its objective of timely project completion.

Planning and Selection of Heavy Construction Equipment in Civil Engineering

Plastics are inexpensive, light in weight as well as durable materials that may conveniently be molded into several items which search for employed in an array of uses. As a result, the generation of plastics materials has exploded substantially in the past several years. Up-to-date quantities of their application, as well as disposal, made numerous climatic problems. Waste plastic items are reclaimed when they are redirected from various processes of littering. Plastic packaging is particularly visible in form of the container because of the light and portable character of both flexible as well as rigid plastics. Developing the products by repairing, reusing, or even remanufacturing will assist in fewer products shifting into the waste products stream. The objective of this chapter is to review the recovery, direct reuse and incineration of polyethylene terephthalate (PET) bottles based recycling system, wherein widely used PET bottles are reprocessed in the form of both fiber as well as bottles.

Materials Recovery, Direct Reuse and Incineration of PET Bottles

The construction industry consumes a substantial amount of raw materials in its processes and the output is obviously the product and most importantly the waste material. Other than that, the construction industry is well known as one of the worst environmental polluters. This study is to determine the use of waste minimisation technique in creating sustainable waste management in order to identify the technique which has the most capabilities to reduce on-site waste. The objective of this study is to assess the waste minimization techniques taken from the 4R concept (which includes reduce, reuse, recycle and recovery techniques) in minimizing the waste in construction waste management. The most used waste minimization technique found in the 4R concept would be waste reduction. This shows that the local construction industry has the knowledge necessary to plan out the waste management processes but the implementation is still far from satisfying. Additionally, the findings reveal that because the industry is profit-driven, construction practitioners are motivated by profit to adapt to this techniques.

Reduce, Reuse, Recycle and Recovery in Sustainable Construction Waste Management

Purchasing with cash, financing through a loan, renting and leasing are four most common ways for Construction Equipment Acquiring (CEA) For having the best result in profit for a construction industry choosing the best alternative for obtaining equipment is one of the most important issues The optimum acquisition strategy comes from accurate estimates of revenues and cost and also some non-financial factors that affect the choosing specific acquisition mode The purpose of this report is to identify these factors To achieve the research objective, a wide literature review has conducted As mentioned before, two categories of factors participate in construction equipment acquisition Financial factors are identified through different literatures Non-financial factors are mostly experimental and cannot be identified using literatures For recognizing these factors a semi structured interview has conducted with construction professionals The result of this study can be used for construction manager to make a better decision in CEA

Factors affecting construction equipment acquisition methods in Malaysia

Selection of the material and design of earthquake resistance structures are an important issue today. Many people die every year due to inappropriate design and selection of the materials. There are several software to be used for structural design of buildings, however they just design the structure based on some limited standards. There is a need to develop a computer-based earthquake resistant design model to integrate the current market’s software with different design standards of different countries. The objective of this study is to propose a model to integrate the local structural design standards/codes with available market’s programs. To achieve this objective, Microsoft Excel was used as the core of the model to be integrated with one of the market’s program. Then, the model was developed in three phases. To test the model, the Iranian design standard (Code 2800) was used to design a 7-story apartment. The results show that the model can be fully integrated with those market’s programs which support Microsoft Excel. The result of Phase 1 of the model is useful to select the optimum selection of the material while Phase 2 and 3 contribute to design of the earthquake resistant structure.

Masoud Navazandeh Sajoudi

Papers

Reduce, Reuse, Recycle and Recovery in Sustainable Construction Waste Management

Factors affecting construction equipment acquisition methods in Malaysia

An Integrated Model to Design Earthquake Resistant Structures