rapport 1129 Potentialbedömning av flygaskor ...

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VÄRMEFORSK Short English Summary Over the next few years, about 200 000–800 000 m 3 of contaminated sediments, with a muddy, slimy texture, high water ratio and low strength, shall be dredged annually in the development of ports and maintenance dredging of navigable waterways. Dumping at sea is limited since the dredged materials are contaminated. Land disposal requires transports and land area and is thus high in costs. In the construction of new port areas, large volumes of crushed rock, etc. are normally used as construction filling materials. These materials can be replaced by stabilised and solidified dredged materials, with modified geotechnical properties. The method of stabilising / solidifying (s/s) contaminated dredged materials has been used internationally for a long period of time, Holm et al. (2009) and, in more recent years, even in the Nordic countries. In Sweden, for instance, the Port of Gävle and the Port of Oxelösund have received permissions to reuse s / s-treated contaminated dredged materials in the port structures. Reuse of the stabilised / solidified masses in a geotechnical structure is supported by the new Framework Directive (2008/98/EC) on waste where great emphasis is placed on recycling. Within the project, fly ashes were inventoried with respect to suitability and availability. Five fly ashes, both individual fly ashes and mixtures of different fly ashes, were investigated in the laboratory as a binder component in a binder mix consisting of 50% cement, 20% Merit 5000 and 30% fly ash. Sediment from the Port of Gävle were stabilised with a binder mixture amount of 150 kg/m 3 . Produced samples were examined in terms of strength, permeability and leaching. An assessment of the fly ashes’ potential was performed based on technological, environmental and economical aspects, as well as market demand and the acceptance of stabilised and solidified dredged materials as construction material. The results show that fly ash, together in a binder mixture with construction cement and Merit 5000, has good potential as a binder. There is a clear correlation between the CaO content of fly ashes and compressive strength of the stabilised samples, whereas maximum compressive strength was obtained with the fly ash with a maximum content of CaO. All stabilised samples passed the basic criterion of compressive strength > 140 kPa, with the lowest value being 300 kPa and with a median of just over 500 kPa after 91 days. The samples had a low permeability between 10 -8 m / s and 10 -9 m / s. Leaching tests showed that the stabilised material’s leaching of metals was low and that organic pollutants were barely detectable. A binder mixture with 30% fly ash provides a cost reduction of the binder of approximately 25%. High standards are required for port constructions, which means high demands on the quality of the binders used in the stabilisation and solidification processes. Therefore, a sturdy binder mixture that is capable of handling a variation in the quality of fly ash and sediment materials, plus a variation in the binder quantity involved in the stabilised material. The need for large volumes of binders means that binder suppliers must cooperate and that the logistics needed to ensure delivery of fly ash in an s / s project is a process that requires good preparation. vi
Executive Summary VÄRMEFORSK Background Dredging for the development of ports and the maintenance dredging of waterways and ports means that large volumes of contaminated sediment need to be taken care of. The most troublesome are the sediments that are fine-grained and contaminated with metals, organic or organometallic (e.g. organotin) contaminants. Over the next few years, about 200 000–800 000 m 3 of contaminated sediments have to be handled annually due to maintenance dredging and port expansions. Gävle Port alone shall dredge up to 1 million m 3 of metal contaminated sediments during the years 2012–2014. These dredged materials are characterized by a muddy texture, high water ratio and low strength. The possibility of dumping at sea is limited since the dredged materials are contaminated. Moving the dredged materials to disposal sites on shore requires transportation and land area resulting in high costs. There is a great need to expand ports which means that large volumes of crushed rock and other earth materials are required to be transported to the port for the use in conventional construction of new port areas. The project STABCON (www.stabcon.com) has shown that a binder consisting of cement (construction cement) and Merit 5000 (steel slag), after stabilisation and solidification (s / s), can modify dredged materials so that predetermined geotechnical and environmental characteristics can be achieved. These masses can be used as filling materials in port structures and even replace crushed rock as filling material. Binder recipes are site specific and depend on, for example, sediment type/ dredged materials, contaminant type, contaminant content, etc. Stabilisation and solidification (s / s) means that binder is added to soft sediment / dredged materials in order to modify the strength, permeability and leaching characteristics. Stabilisation means that contaminants are chemically transformed into less mobile forms whilst solidification is a process which transforms the masses into a solid form leading to an increased strength, improved deformation characteristics and reduced permeability of dredged materials. The use of s / s treated contaminated dredged material in geotechnical constructions have been described in STABCON by Holm et al. (2009). Aims & Objectives The aim of this project was, from technical, environmental and economic aspects, to investigate the potential for a fly ash, or a combination of fly ashes, to be used as the components of a binder in the stabilisation and solidification of contaminated dredged material. The target audience has principally been port owners and other commercial proprietors whom are facing projects where contaminated sediments are to be disposed of. Binder producers, specifically fly ash producers, are also naturally targeted. Potential Assessment This Potential assessment has been carried out on five different fly ashes in a binder mix together with construction cement and Merit 5000 for s /s contaminated sediments from the Port of Gävle. The fly ashes’ potential was evaluated both by an inventory based on literature studies and interviews with fly ash producers and by laboratory vii
Page 1: MILJÖRIKTIG ANVÄNDNING AV ASKOR 1
Page 5 and 6: Förord VÄRMEFORSK Föreliggande p
Page 7 and 8: Abstract VÄRMEFORSK Under kommande
Page 9: Sammanfattning VÄRMEFORSK Under de
Page 13 and 14: VÄRMEFORSK sary compressive streng
Page 15 and 16: VÄRMEFORSK great interest in the s
Page 17: Innehållsförteckning VÄRMEFORSK
Page 20 and 21: VÄRMEFORSK För att utvärdera de
Page 22 and 23: VÄRMEFORSK Figur 2.2 Förväntade
Page 24 and 25: VÄRMEFORSK Figur 2.3 Principskiss
Page 26 and 27: VÄRMEFORSK Objekt År s/s Föroren
Page 28 and 29: VÄRMEFORSK Bærum I Bærums kommun
Page 30 and 31: VÄRMEFORSK Samtliga prover har und
Page 32 and 33: VÄRMEFORSK Resultat för ytterliga
Page 34 and 35: VÄRMEFORSK Av de övriga resterna
Page 36 and 37: VÄRMEFORSK 3. bindemedel beståend
Page 38 and 39: VÄRMEFORSK 4.1.3 Karaktärisering
Page 40 and 41: VÄRMEFORSK 4.1.4 Miljömässig kar
Page 42 and 43: VÄRMEFORSK Tryckhållfasthet [kPa]
Page 44 and 45: VÄRMEFORSK För examensarbetet (Fo
Page 46 and 47: VÄRMEFORSK Tryckhållfasthet [kPa]
Page 48 and 49: VÄRMEFORSK Figur 4.8 Typiskt betee
Page 50 and 51: VÄRMEFORSK Cu-halt (mg/kg TS) 0,14
Page 52 and 53: VÄRMEFORSK Zn-halt (mg/kg TS) 0,25
Page 54 and 55: VÄRMEFORSK Efter 91 dygn låg den
Page 56 and 57: VÄRMEFORSK Bindemedelsmängd, kg/m
Page 58 and 59: VÄRMEFORSK I inventeringen av flyg
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VÄRMEFORSK 6 Potentialbedömning P
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VÄRMEFORSK meabilitet hos lera < 1
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VÄRMEFORSK som är nivå för mind
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VÄRMEFORSK Något klart samband me
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VÄRMEFORSK massor är Gävle Hamn
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VÄRMEFORSK CaO-halt ger högre try
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VÄRMEFORSK Bindemedelsleverantöre
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VÄRMEFORSK 9 Litteraturreferenser
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Innehållsförteckning 1. Syfte och
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lir rätt blandning. För att gräv
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etc., så är det oftast endast nå
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Dimensioneringen av geokonstruktion
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Tabell 4.1 Exempel på olika skeden
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5.2 Föroreningsinnehåll De övers
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Flygaskors egenskaper/kvalitet Flyg
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likhet med ved- och torvaska ingår
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Torrdensitet ρ 2,2 2,1 2 1,9 1,8 1
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Tryckhållfasthet, MPa 14 12 10 8 6
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Denna gruppering baseras på data f
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Figur 6.6 Tryckhållfastheten för
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A1 A2 A3 Totalt SCA Ortviken/ Östr
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2. Kornfördelning, sediment Figur
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3. Kornfördelning askor Figur 3. K
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Figur 5. Kornfördelningskurva Aska
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4. Tryckhållfasthet, densitet och
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Figur 12. Permeabilitetsutveckling
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5.2 Stabiliserat sediment 3 Figur 1
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Lakning L/S=10, Gävle hamn sedimen
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