In Swedish tunnel construction, a critical issue that has been repeatedly acknowledged is corrosion and, consequently, failure of the rock bolts in rock support systems. The defective installation of rock bolts results in the formation of cavities in the cement mortar that is regularly used to fill the area under the dome plates. These voids allow for water-ingress to the rock bolt assembly, which results in corrosion of rock bolt components and eventually failure. In addition, the current installation technique consists of several manual steps with intense labor works that are usually done in uncomfortable and exhausting conditions, e.g., under the roof of the tunnels. Such intense tasks also lead to a considerable waste of materials and execution errors. Moreover, adequate quality control of the execution is hardly possible with the current technique. To overcome these issues, a nonshrinking/ expansive cement-based mortar filled in the paper packaging has been developed in this study which properly fills the area under the dome plates without or with the least remaining cavities, ultimately that diminishes the potential of corrosion. This article summarizes the development process and the experimental evaluation of this technique for the installation of rock bolts. In the development process, the cementitious mortar was first developed using specific cement and shrinkage reducing/expansive additives. The mechanical and flow properties of the mortar were then evaluated using compressive strength, density, and slump flow measurement methods. In addition, isothermal calorimetry and shrinkage/expansion measurements were used to elucidate the hydration and durability attributes of the mortar. After obtaining the desired properties in both fresh and hardened conditions, the developed dry mortar was filled in specific permeable paper packaging and then submerged in water bath for specific intervals before the installation. The tests were enhanced progressively by optimizing different parameters such as shape and size of the packaging, characteristics of the paper used, immersion time in water and even some minor characteristics of the mortar. Finally, the developed prototype was tested in a lab-scale rock bolt assembly with various angles to analyze the efficiency of the method in real life scenario. The results showed that the new technique improves the performance of the rock bolts by reducing the material wastage, improving environmental performance, facilitating and accelerating the labor works, and finally enhancing the durability of the whole system. Accordingly, this approach provides an efficient alternative for the traditional way of tunnel bolt installation with considerable advantages for the Swedish tunneling industry.

The EU Waste Framework Directive 2008/98/EC states that all member states should take all necessary measures in order to achieve at least 70% re-use, recycling or other recovery of non-hazardous Construction and Demolition Waste (CDW) by 2020. In response, the Horizon 2020 RE4 project consortium (REuse and REcycling of CDW materials and structures in energy efficient pREfabricated elements for building REfurbishment and construction) consisting of 12 research and industrial partners across Europe, plus a research partner from Taiwan, was set up. For its success, the approach of the Project was manifold, developing sorting technologies to first improve the quality of CDW-derived aggregate. Simultaneously, CDW streams were assessed for quality and novel applications developed for aggregate, timber and plastic waste in a variety of products including structural and non-structural elements. With all products considered, innovative building concepts have been designed in a bid to improve future reuse and recycling of the products by promoting prefabricated construction methods and modular design to ease future recycling and increase value of the construction industry. The developed technologies and products have been put to the test in different test sites in building a two-storey house containing at least 65% of CDW. © 2019, © 2019 The Author(s)..

Existing territorial life cycle assessments (LCAs) consider all activities in a given geographical area, defined as the foreground system, but cannot lead to operational decisions. In product scale LCA, the foreground system is defined as the part of the system directly controlled by an actor and is thus more adapted to compare possible scenarios within a decision perimeter. The present paper uses that concept applied to a geographical area. The developed method consists of five steps: (a) definition of the foreground material flow analysis (MFA) or LCA system corresponding to the decision perimeter; (b) territorial MFA; (c) geo-location of activities and downscaling of territorial flows to individual activities; (d) calculation of local transport distances; and (e) calculation of LCA impact indicators. The case study concerns the management of primary and secondary resources of basic quality aggregates (BQAs) in the Loire-Atlantique department (France) in 2012. Our results show that the amount of recycled cement concrete is only 7% of total consumed BQAs, although 90% of cement concrete demolition waste (CCDW) is recycled. The environmental impacts are importantly related to off-site activities. Local impacts are mainly driven by the transport of aggregates. For land planning, a concentration of fewer recycling facilities with high authorised production capacities in main cities, close to where CCDW is mainly produced, would divide transport needs in half and thus considerably reduce environmental impacts.

Främjandet av en cirkulär ekonomi inom byggsektorn har blivit ett viktigt ämne i Europa, mycket på grund av att såväl byggande som mängder uppkommet bygg- och rivningsavfall ökar för varje år, samtidigt som mål för att mildra miljöpåverkan tillkommer. Det är därför nödvändigt att hitta alternativ i form av så kallade sekundära råmaterial (återanvända eller återvunna från t.ex. bygg- och rivningsaktiviteter), som kan användas i byggsektorn och därmed minska uttag av primära resurser, i linje med principer för hållbar utveckling.

Det huvudsakliga målet med föreliggande rapport är att identifiera de viktigaste möjliggörarna (som driver önskad utveckling framåt) och hindren (eller trösklar, som bromsar eller helt stoppar önskad utveckling), för ökad användning av sekundära råmaterial i Europas byggsektor. Goda exempel från länder där återvinningsgraden är högre än i Sverige kan ligga till grund för hur vi kommer vidare nationellt. Därför har tre länder, där större andel av avfall återanvänds eller återvinns, valts ut för djupare analys av vad som där möjliggjort respektive bromsat (regelverk, konsumentbeteende, etc.) en utveckling till ökad återvinning av bygg- och rivningsavfall. De länder som valts är: Nederländerna, Frankrike och Tyskland.

Enligt olika rapporter och personlig kommunikation med aktörer i såväl Frankrike som Tyskland, är de viktigaste trösklarna användarens/kundens bristande tillit till den återvunna ballastens kvalitet, samt avsaknad av riktlinjer/handledning i hur avfall ska hanteras och användas. Den huvudsakliga möjliggöraren i såväl Frankrike som Tyskland var ökad efterfrågan i spåren av miljömärkning av byggnader.

I Nederländerna har arbetet mot en ökad användning av sekundära råmaterial pågått under lång tid. En viktig utgångspunkt för detta har varit att tillgången till primära råmaterial är relativt begränsad i landet. Framtagandet av lagstiftning som gäller för samtliga byggnadsmaterial, både primära och sekundära, har skapat tydliga ramar för användningen av material i konstruktioner. Tillämpningen av en särskild uppsättning gränsvärden och försiktighetsåtgärder för användning av sekundära råmaterial med högre föroreningsgrad (IBC-material) har också inneburit att sådana material har kunnat användas, åtminstone i större projekt där det funnits möjlighet att investera i tätskikt, utföra övervakning och hantera tillkommande administration. Statliga aktörer har varit tydliga med att sekundära råmaterial ska användas i större utsträckning och också i många egna infrastrukturprojekt använts sig av sådana. På senare år har de blivit än tydligare i sina ambitioner och policys att verka för en cirkulär omställning.

Construction and Demolition Waste (CDW) accounts for approximately 25-30% of all waste generated across Europe each year. However, Waste Framework Directive 2008/98/EC requires from all EU member states to achieve at least 70% re-use, recycling or other recovery of non-hazardous CDW by 2020. In response, the Horizon 2020 RE4 Project (REuse and REcycling of CDW materials and structures in energy efficient pREfabricated elements for building REfurbishment and construction) consortium was set up. Its main aims are to assess the quality of various CDW fractions (e.g. mineral aggregate, timber, plastics, silt & clay), improve the quality of mineral aggregates and develop different building elements/components which contain at least 65% of CDW. Innovative building concepts will also be developed in an effort to improve recycling rates of future buildings through the use of prefabrication and modular design. The developed products and technologies will be assessed in a number of test sites by building 2-storey demonstration houses.