A mild alkali treated jute fibre controlling the hydration behaviour of greener cement paste

To reduce the antagonistic effect of jute fibre on the setting and hydration of jute reinforced cement, modified jute fibre reinforcement would be a unique approach. The present investigation deals with the effectiveness of mild alkali treated (0.5%) jute fibre on the setting and hydration behaviour of cement. Setting time measurement, hydration test and analytical characterizations of the hardened samples (viz., FTIR, XRD, DSC, TGA and free lime estimation) were used to evaluate the effect of alkali treated jute fibre. From the hydration test, the time (t) required to reach maximum temperature for the hydration of control cement sample is estimated to be 860 min, whilst the time (t) is measured to be 1040 min for the hydration of a raw jute reinforced cement sample. However, the time (t) is estimated to be 1020 min for the hydration of an alkali treated jute reinforced cement sample. Additionally, from the analytical characterizations, it is determined that fibre-cement compatibility is increased and hydration delaying effect is minimized by using alkali treated jute fibre as fibre reinforcement. Based on the analyses, a model has been proposed to explain the setting and hydration behaviour of alkali treated jute fibre reinforced cement composite

Carbon dioxide sequestration on fly ash/waste glass alkali-based mortars with recycled aggregates: Compressive strength, hydration products, carbon footprint, and cost analysis

Carbon dioxide sequestration is crucial for limiting global warming. However, carbon dioxide sequestration in saline aquifers has large risks and also involves a very high cost. In this context sequestration of carbon dioxide in cementitious construction materials can not only prevent carbon dioxide to be released into the atmosphere but also accelerate curing and strength development of those materials. Since so far no studies were performed on alkali-based materials, this chapter discloses results of an investigation concerning carbon dioxide sequestration on fly ash/waste glass alkali-based mortars with recycled aggregates. Compressive strength, hydration products, carbon footprint, and cost analysis were also studied.The authors would like to acknowledge the financial support of the Foundation for Science and Technology (FCT) in the frame of project IF/00706/2014-UM.2.15.info:eu-repo/semantics/publishedVersio

Managing Uncertainty in Environmental and Cost Life Cycle Studies of Building Design

In order to mitigate global warming and address other pertinent environmental issues, it is important to reduce the environmental impact from the building stock. Emissions can be large for both operational energy consumption and production of materials. It is therefore important to find building design solutions that consider production, operation and maintenance in order to minimise the climate impact of a building during its entire lifetime. At the same time, the production of buildings has to be cost-efficient. In the design of buildings, both environmental impact and cost must be evaluated in order to make well-supported decisions.   There are many uncertainties in the design phase of buildings. This study explored the uncertainties that occur when a life cycle perspective is adopted in building design decisions and developed an approach to manage them. Addressed issues were secondary effects of design changes, material data gaps and how subjective choices and parameter uncertainties can be managed in conjunction. This was done by developing the Effect and Consequences Evaluation (ECE) method and the Decision Choices Procedure (DCP), which were combined into a general approach. The presented approach will provide a structured means to set up system boundaries and manage uncertainties when life cycle studies are used as decision support for optimising building design. Several case studies were carried out to penetrate specific issues, and the final approach was demonstrated with a case study of selecting optimal insulation thickness when designing the building envelope.   The results can be used to support decisions on where and how to effectively make improvements when subjective choices and parameter uncertainties are considered in the study. This will facilitate decisions on different building design solutions so that the option with the lowest total environmental impact and a reasonable cost can be chosen

Termisk inomhuskomfort vid värmeböljor

Climate change with more frequent and longer heat waves in the future will be a challenge for the cities in Sweden. With more frequent heat waves the demand for mechanical cooling will increase. This will lead to higher energy consumption with the consequence that the emissions of greenhouse gases increase and affect climate change even further. To avoid thermal discomfort during the summers the design and constructions in the building have central roles. Sun protecting measures like awnings and shadings as well as window airing can have a large impact on the indoor temperature. This study investigates how different climates affect the indoor temperature in buildings and the results illustrate the problems with thermal comfort that can arise. Additionally, long lasting technical solutions to mitigate high indoor temperatures during heat waves were evaluated. The results show how different prerequisites, as well as common solutions, for buildings affect the thermal comfort. They also identify the importance of a holistic system view of the building during the design so that the thermal comfort aspects are considered together with energy improvement measures

Livscykelstudie av kontor med kombinerad betong- och träkonstruktion

Vasakronan has produced an office building were seven of the floors are mainly made in concrete and two floors are mainly made of wooden materials.  As Vasakronan had little previous experience with wooden construction works they were interested in comparing the different production methods from an environmental and economic perspective. The main purpose of the project was to analyze the long-term environmental impact of different building methods with alternative design and production as well as material choice and on-site systems. A secondary purpose was to assess the economic consequences of different construction solutions. The goals were to: provide advice and suggestions on how different material choice, construction solutions and assembly methods can be used from their environmental and economic properties. find environmental hot-spots in the building process. contribute with knowledge and experience to develop methods regarding life cycle assessment (LCA) and calculation of life cycle cost (LCC) for building projects.  compare differences between constructions in concrete and wood. An LCA was carried out on the whole building and LCA and LCC calculation were conducted to compare the environmental impact and cost of concrete and wooden constructions.  The results include global warming potential, eutrophication potential, acidification potential, stratospheric ozone depletion potential, photooxidants creation potential and present costs. The data were collected by the contractors during production to ensure that the results are based on the finished building and not assumptions made during the design stage. The report shows the difficulties that arise during life cycle studies of buildings but also provides guidance how to solve them in this particular case, which can be used as a base for continued development of methods.Ändringar: Rapporten publicerad 2018-12-21. Rapporten/fulltexten reviderad 2019-04-04 med följande ändringar:Rapporten har uppdaterats fr o m 2019-04-04 efter att beräkningarna för miljöpåverkan korrigerats, vilket främst påverkade resultaten för ODP och POCP. Påverkan på resultaten har justerats i resultat- och diskussionsdelarna av rapporten.Framtidens Biobaserade Byggande och Boend

Ta tempen på entreprenadföretagens hållbarhetsarbete – förstudie

Contractors are expected to present their sustainability work in connection with procurement. But what is required is not always clear. The client could for example ask what the contractors are doing to contribute to environmentally or socially sustainable development. This pre-study surveys how the clients set requirements for sustainability work in procurement today and how the contractors respond to these requirements in their tenders, but also how the contracting companies work with sustainability in practice. The contractors hope that the concepts and requirements used in sustainability work will be clearer, more rigorous and easier to live up to so that they can truly contribute to a sustainable society. They would like to see it as a long-term work where they build up skills and routines in many projects instead of just a few pilot projects. Based on the results, the need of new tools or better use of existing tools to strengthen the work on sustainable construction projects were identified. The pre-study is carried out mainly through interviews with representatives from 15 companies as well as analysis and discussion of the answers during one workshop

Termisk inomhuskomfort vid värmeböljor

Climate change with more frequent and longer heat waves in the future will be a challenge for the cities in Sweden. With more frequent heat waves the demand for mechanical cooling will increase. This will lead to higher energy consumption with the consequence that the emissions of greenhouse gases increase and affect climate change even further. To avoid thermal discomfort during the summers the design and constructions in the building have central roles. Sun protecting measures like awnings and shadings as well as window airing can have a large impact on the indoor temperature. This study investigates how different climates affect the indoor temperature in buildings and the results illustrate the problems with thermal comfort that can arise. Additionally, long lasting technical solutions to mitigate high indoor temperatures during heat waves were evaluated. The results show how different prerequisites, as well as common solutions, for buildings affect the thermal comfort. They also identify the importance of a holistic system view of the building during the design so that the thermal comfort aspects are considered together with energy improvement measures