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- Arm, Maria, et al.
(författare)
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Förutsägelse av långtidsegenskaper hos restprodukter : teknik och miljö i vägar
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In Sweden, use of industrial by-products is still hindered by concern for their long-term properties. This report describes a three-year research project aiming to identify the key processes of ageing related to the usefulness of by-products in roads; investigate the consequences of these processes for technical and environmental properties of the by-products, and propose a method for accelerated ageing to predict long-term properties. The project has compared naturally aged samples of two by-products used as sub-bases in existing asphalt paved roads with samples of fresh by-products from producers' piles. Steel slag of electric arc furnace type and municipal solid waste incinerator (MSWI) bottom ash were chosen. The samples were thoroughly characterized in order to identify which ageing processes had been crucial. The working hypothesis was that ageing processes lead to changes in pH, effective particle size and mineralogy, which in turn determine leaching, stiffness and stability of the material. One of the conclusions from the project is that the test results confirmed that the pavement edge material is ageing faster than the road centre material is.
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- Arm, Maria, et al.
(författare)
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Gasbildning i aska
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)
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- Arm, Maria, et al.
(författare)
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How Does the European Recovery Target for Construction & Demolition Waste Affect Resource Management?
- 2017
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Ingår i: Waste and Biomass Valorization. - : Springer Netherlands. - 1877-2641 .- 1877-265X. ; 8:5, s. 1491-1504
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Tidskriftsartikel (refereegranskat)abstract
- The revised EU Waste Framework Directive (WFD) includes a 70 % target for recovery of construction and demolition (C&D) waste. In order to study the potential change in the resource management of the main C&D waste fractions, as a consequence of fulfilling the WFD target, a Nordic project (ENCORT-CDW) has been performed. Waste fractions studied included asphalt, concrete, bricks, track ballast, gypsum-based construction materials and wood. Recovery scenarios were identified and estimations were made regarding expected savings of primary materials, impact on transport, and pollution and emissions. For wood waste, the main differences between re-use, material recycling and energy recovery were evaluated in a carbon footprint screening based on life cycle assessment methodology. The study concluded that the EU recovery target does not ensure a resource efficient and environmentally sustainable waste recovery in its present form since: It is very sensitive to how the legal definitions of waste and recovery are interpreted in the Member States. This means that certain construction material cycles might not count in the implementation reports while other, less efficient and environmentally safe, recovery processes of the same material will count. It is weight-based and consequently favours large and heavy waste streams. The result is that smaller flows with equal or larger resource efficiency and environmental benefit will be insignificant for reaching the target. It does not distinguish between the various recovery processes, meaning that resource efficient and environmentally safe recovery cannot be given priority. Improved knowledge on C&D waste generation and handling, as well as on content and emissions of dangerous substances, is required to achieve a sustainable recovery.
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- Arm, Maria, 1958-
(författare)
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Mechanical Properties of Residues as Unbound Road Materials - experimental tests on MSWI bottom ash, crushed concrete and blast furnace slag
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For recycled aggregates and industrial by-products to beused correctly in road construction, it is necessary to knowtheir properties. Existing material specifications and testmethods for aggregates used in Sweden and in many othercountries are indirect and are based on empiricism. Over theyears they have been adjusted to conventional aggregates, whichmakes the introduction of new materials difficult. Research oftheir properties is being conducted in many places althoughknowledge has been inadequately disseminated.The objective of this thesis is to increase knowledge of themechanical properties of certain selected residues for improveddesign of pavements using these residues.The study has concentrated on residues in unbound roadlayers. The materials selected were processed municipal solidwaste incinerator (MSWI) bottom ash, crushed concrete andair-cooled blast furnace slag (AcBFS). The deformation onloading, the possible strength development over time and theresistance to mechanical and climatic action were studied inthe laboratory and in the field. The results were compared withthose of the conventional aggregates they could possiblyreplace, such as sand, gravel and crushed rock. The methodsused in the laboratory were cyclic load triaxial tests, LosAngeles tests, micro-Deval tests and freeze-thaw tests. In thefield, test sections with residues and reference sections withconventional aggregates in the unbound layers were monitored bymeans of falling weight deflectometer (FWD) measurements.The laboratory results showed that a high content ofunburned material in MSWI bottom ash limits the resilientmodulus but not the permanent deformation to the same extent.Both laboratory and field results showed several years’growth in stiffness for unbound layers with crushed concreteand AcBFS, which is not present for unbound layers with naturalaggregates. This was thought to be caused by calciumdissolution and precipitation in the compacted material layer.A special investigation of the material in question, togetherwith knowledge of the planned construction, could permit ahigher value to be used in the design modulus than for crushedrock and thus benefit from the increased stiffness.The Los Angeles test and other tests developed forsingle-sized aggregates did not really justify the performanceof the materials studied. Recycled aggregates and otherresidues, as well as conventional unbound road materials,should be analysed using cyclic load triaxial tests in thelaboratory and FWD measurements in the field, both of whichtake into account the whole composite material or layer.Consequently, a new methodology for material assessment andcomparison is proposed, based on permanent deformations incyclic load triaxial tests.According to the laboratory and field tests, some bottom ashcould be used, not only in embankments and capping layers butalso to bear the stress levels expected in a sub-base. Recycledaggregates and other residues should be used near the source ofproduction and not necessarily in roads with low trafficvolumes. Their properties should be used to the greatestpossible extent although their limitations must be taken intoaccount.Key Words:residues; unbound materials; MSWI bottom ash;crushed concrete; blast furnace slag; mechanical properties
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- Arm, Maria, et al.
(författare)
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Pulp mill fly ash for stabilization of low-volume unpaved forest roads — field performance
- 2014
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Ingår i: Canadian journal of civil engineering (Print). - : Canadian Science Publishing. - 0315-1468 .- 1208-6029. ; 41:11, s. 955-963
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Tidskriftsartikel (refereegranskat)abstract
- Increased temperatures and rainfalls will give more settlements and less bearing capacity in gravel roads, which will have implications for the forestry. Pulp mill fly ash without additives was used for stabilizing the road base of a low-volume gravel road. A two-year monitoring of the road was conducted, including measurements of achieved ash content, density, water infiltration capacity, and load bearing capacity. The results showed that the ash-stabilized sections performed better than conventionally upgraded sections and also achieved increased bearing capacity over time. Hydration of the fly ash increased the stiffness and decreased the permeability of the road base. The differences were more pronounced during spring thaw. Best performance was achieved in the section with thicker ash stabilized layer.
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