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1.	Andersson, Patrik, 1974, et al. (författare) Framtidsbilder för samhällsbyggnad 2006 Rapport (övrigt vetenskapligt/konstnärligt)abstract Framtidsbilder för samhällsbyggnad 2020De kommande 15 åren står institutionen för Bygg- och miljöteknik inför stora förändringar. Därför har institutionen initierat projektet Framtidsbilder 2020 där man engagerat en framtidspanel bestående av elva yngre disputerade forskare. Arbetet inleddes med ett breddgruppsmöte där 110 personer representerande institutionens personal och studenter deltog. Vid mötet identifierades ett antal trender och osäkra utvecklingar som påverkar framtiden inom samhällsbyggnadsområdet. Deltagarna bidrog också med idéer till en önskvärd utveckling, vilket har sammanställts och utgör grunden till en gemensam önskvärd framtid/vision för institutionen. Materialet från breddgruppsmötet har bearbetats av Framtidspanelen och resulterat i fyra scenarier som beskriver hur samhällsbyggnadsområdet kan se ut år 2020. Syftet med framtidsbilderna är att de ska vara vägledande för institutionens beslut och förhållningssätt under de kommande åren.Fyra scenarierTurning TorsoSamhället präglas av en ekonomi som är på uppgång, och av ett nytänkande och öppet samhälle. Materiell status och individualism är viktigt. Detta leder till en hög arbetsbelastning samt krav på exklusiva varor av hög kvali-tet. Det finns en stor medvetenhet om miljöpåverkan och klimatförändringar och lösningarna för att klara energiförsörjningen är innovativa.Eco-metropolenDet sveper en grön våg genom dagens samhälle. Under de senaste 15 åren har vi insett att jorden skall vara en bebolig plats även åt dem som kommer efter oss. Vi söker ständigt efter nya, mer förfinade metoder att tillvarata de resurser vi har. Samhället och individen är i balans. Ekonomin är god och vi är miljömedvetna, trygga och integrerade. Nytänkande premieras och icke- materialistiska värderingar står högt i kurs. Vi tänker individuellt, men agerar mer än gärna för kollektivets bästa. Utbildning är gratis TrädgårdsstadenEtt samhälle där vi lärt oss hantera stress, men känner oss otrygga och helst umgås i slutna sociala sammanhang. Vi bor enkelt inne i stan, eller gärna på landsbygden nära storstäderna. Minskade behov av högutbildade i samhället gör att vi har svårt att rekrytera studenter till teknikutbildningar. Det traditionella tankesättet leder till kulturkrockar med företag och personer från andra länder.Gated communitiesFörsämrad ekonomi och ökad egoism har lett fram till ett stressat, otryggt och segregerat samhälle. Accelererande klimatförändringar och ökad miljö-påverkan skrämmer oss, men trots det åtgärdar vi inte problemen, utan koncentrerar oss på konsekvenserna. Arbetslöshet i samhällsbyggnadssek-torn leder till sänkt status för samhällsbyggaren. Vi har därför svårt att rekrytera studenter, och även forskningen har låg status.
2.	Alén, Claes, 1949, et al. (författare) Slitsmurar som permanenta konstruktioner 2006 Rapport (övrigt vetenskapligt/konstnärligt)abstract Slitsmursteknik är internationellt en vanligt förekommande metod. Den användes framförallt vid djupa schakter för källare och infrastrukturkonstruktioner i innerstadsbebyggelse. Ett annat användningsområde är som tätskärm vid dammar eller deponier. När slitsmuren användes vid djupa schakter utnyttjas den normalt också i den permanenta konstruktionen, vilket ökar metodens ekonomiska konkurrenskraft. Vid tät stadsbyggnad har metoden stora fördelar tack vare sin begränsade omgivningspåverkan (buller, damm, deformationer etc) jämfört med spontslagning och sin goda ekonomi när den kan utnyttjas som permanent konstruktion.I Sverige har slitsmurar använts endast vi ett fåtal tillfällen och då endast som temporär konstruktion. De senaste exemplen är Götatunneln i Göteborg och Citytunneln i Malmö.Med ett ökat undermarksbyggande i våra större städer har intresset ökat för att också utnyttja slitsmuren i den permanenta konstruktionen och därigenom öka den ekonomiska nyttan och även ta mindre mark i anspråk under byggandetI avsikt att utreda möjligheten att kunna acceptera slitsmuren i permanenta konstruktioner tog Vägverket under år 2004 initiativet till ett branschgemensamt utvecklingsprojekt med Vägverket, Banverket och SBUF som finansiärer. Projektet skall resultera i en rekommendation om vilka begränsningar och förändringar som erfordras för att kunna utnyttja tekniken . Alternativt skall projektet utmynna i ett motiverat avstyrkande av tekniken. Behov av ytterligare utvecklingsarbete skall också identifierats.För projektets genomförande har en projektgrupp tillsatts representerande expertis inom de olika områden som är relevanta för slitsmurar. En referensgrupp med representerande för myndigheter, utförare , konsulteroch högskolor har sammankallats vid två tillfällen. Enskilda personer i referengruppen har intervjuats i speciella frågeställningar.Efter inledande litteraturstudier och seminarier i samband med en slitsmurskonferens arrangerad av Vägverket och Banverket har arbetet koncentrerats på följande områden:-Slitsmurens beständighet, framför allt frågeställningar beträffande krav på material ochutförande, konstruktiva lösningar samt sprickviddsbegränsninagr -Geotekniska frågeställningar speciellt med koppling till påverkan på slitsmurens täthet, kvalitet och beständighet.-Inverkan av stödvätska på den färdiga slitsmurskonstruktionens egenskaper -Internationella erfarenheter; brukare och entreprenörer har intervjuats om erfarenheter i driftsskedet och under utförandet. Arbetet och analyser har baserat på litteraturstudier, enkätsvar från beställare och entreprenörer, intervjuer med experter och myndigheter samt egna erfarenheter avslitsmursarbeten inom projektgruppen.För utredning av stödvätskans inverkan på den färdiga slitsmuren har fältförsök utfört vid Citytunnelprojektet i Malmö. Projektgruppen finner att man med dagens kunskaper kan rekommendera slitsmurar för permanent bruk under vissa förutsättningar t.ex:-Betongens vct skall vara mindre än 0,50-Vid konstruktioner med miljöbelastning motsvarande vägmiljö samt vid krav på torr inomhusmiljö bör en inre betongvägg utföras innanför slitsmuren.-Sprickvidden i permanentskedet bör inte överstiga 0,2mm. -Möjlighet finns att åstadkomma frostbeständig betong där så erfordras.-Den tillåtna vidhäftningsspänningen mellan betong och armering reduceras med 20 %. Vissa frågeställningar bör belysas ytterligare för att eventuellt kunna öka potential och ekonomi för permanenta slitsmurar t.ex:-Ett mer nyanserat sätt att formulera sprickviddskrav för att på ett relevant sätt kunna hantera vattentäthet, beständighet och omgivningspåverkan både i permanent- och utförandeskedet.-Vidhäftningens beroende av stödvätskan-Storlek av belastningar som användes vid dimensionering av slitsmurar-Påverkan på betongens hållfasthet och täthet av stödvätska, tillsatsmedel och arbetsutförande.-Påverkan av slitsmurens täthet på omgivningen.Viktiga faktorer för att uppnå ett bra kvalitet på den permanenta slitsmuren är bl.a:-Arbetesutförandet och erfarenheten hos slitsmursentreprenören är av avgörande betydelse för en bra kvalitet.-Samverkan mellan projektör, entreprenör och beställare är viktigt för att uppnå ett bra resultat. -Armeringens utformning och detaljlösningar vid anslutande bjälklag bör ägnas speciell omsorg. För tätt armerade konstruktioner i syfte att uppnå täta konstruktioner kan motverka sitt syfte.-Stödvätskans egenskaper och hantering har en avgörande inverkan på slutproduktens kvalitet.
3.	Correia, Vera, et al. (författare) Effect of the addition of GGBS on the frost scaling and chloride migration resistance of concrete 2020 Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 10:11 Tidskriftsartikel (refereegranskat)abstract Ground Granulated Blast-furnace Slag (GGBS) can partially replace cement in concrete to improve certain properties. However, some concerns regarding its performance have been raised. This research aimed at investigating the properties of concrete with GGBS, with special focus on its frost scaling and chloride ingress resistance. Concretes with different amounts of GGBS, different efficiency factors, and different air contents have been tested. The effects of other factors, namely the curing temperature, the use of superplasticizer and carbonation, have also been investigated. The results showed that the frost resistance generally decreases with the increase of the amount of GGBS. However, this research showed that it is possible to produce frost resistant concrete with up to 50% of GGBS by changing some properties of the mix (such as increasing the air content). The results also showed a significant improvement of the chloride ingress resistance for concrete with high additions of GGBS.
4.	KNUTSSON, ANNA, 1983, et al. (författare) Freeze/Thaw durability of concrete with fly ash 2011 Ingår i: Nordic Concrete Research. ; Publication No. 43, s. 141-144 Konferensbidrag (refereegranskat)abstract This paper presents results from a study of frost resistance of air entrained concrete with additions of fly ash. In this study, concrete with different additions of fly ash were cured at different ages and elevated temperature prior to the standard frost scaling test. The equivalent water-binder ratio was fixed at 0.45, with efficiency factors of either 0.4 or 1.0. The results show that properly air entrained concrete with fly ash achieved a frost resistance similar or even better than that of Portland cement concrete. Curing for longer ages or at elevated temperature did not improve the freeze/thaw durability.
5.	Lindvall, Anders, 1971, et al. (författare) A Procedure for Verification of Models used to predict Chloride Ingress into Concrete 2006 Ingår i: 2nd fib Congress June 5-8, 2006 - Naples, Italy. - 8889972068 ; 2, s. 454-455 Konferensbidrag (refereegranskat)abstract There are several mathematical models available which predict chloride ingress into concrete. A requirement for all these models is that the predictions both have good precision, i.e. have small scatters, and accuracy, i.e. correspond well with measured data. In this paper a procedure to investigate the precision and accuracy of prediction models, used to predict chloride ingress into concrete, is described. The procedure involves determination of the areas, which the measured and predicted profiles, including their scatters, cover in chloride ingress diagrams. The uncertainties in the measured profiles depend on variations in concrete properties, exposure conditions and uncertainties in the measuring techniques, while the uncertainties in the predicted profiles depend on the uncertainties of the input data in the models. The precision of the models is evaluated by studying the areas of the predicted profiles. If the areas are small the precision is good and vice versa. The accuracy of the models can be evaluated by comparing the areas where the measured and predicted profiles are overlapping each other with the total area of the measured and predicted profiles. The quotient between the overlapping and total areas gives a picture of the accuracy where large and small quotients mean good and bad accuracy respectively.Three predictions models are evaluated with the proposed procedure, namely the ClinConc model (physical model), DuraCrete model (empirical model) and the Error-function model (empirical model). The evaluation has been made in four different exposure conditions; marine submerged, splash and atmospheric conditions and along thaw-salted roads. The verification has been made both for short and long term exposure. The results from the verification are combined into success ratios by multiplying them with weight factors. The weight factors are used to show the relevance of each verification, where verifications made in marine submerged conditions and with long term data are considered more relevant than the other verifications. The final results show that the ClinConc model gives both better precision and accuracy compared with the other models. There were large variations in the accuracy between the different exposure conditions, where the best accuracy for all models was achieved in marine submerged conditions. An explanation to this observation is the difficulties to define appropriate boundary conditions in exposure conditions where the concrete is not constantly exposed to seawater.Finally examples are given service life designs made with the evaluated models for concrete exposed in marine submerged and atmospheric conditions. The service life is defined to be ended when reinforcement corrosion is initiated. The predictions have been made with both mean value and pessimistic approaches, where in the latter all influencing parameters are put in such way that a lower limit of the service life is achieved, to illustrate how uncertainties influence service life predictions. The results show that there are significant differences between predictions made with mean value and pessimistic approaches. This is especially the case if the predicted profiles are flat. The predictions made with the empirical models can, however, be questioned since these are made far beyond the data the models are verified against.
6.	Lindvall, Anders, 1971 (författare) Chloride ingress data from field and laboratory exposure - Influence of salinity and temperature 2007 Ingår i: Cement and Concrete Composites. - : Elsevier BV. - 0958-9465. ; 29:2, s. 88-93 Tidskriftsartikel (refereegranskat)abstract Marine exposure conditions provide an aggressive environment for reinforced concrete structures, mainly due to the occurrence of chloride-induced reinforcement corrosion. There are several influencing factors, but despite a lot of research little is known about the influence from variations in the exposure conditions. Therefore an exposure programme has been made, where concrete specimens, made from one single concrete composition, have been exposed at 12 marine locations around the world, along with a parallel study under laboratory conditions. The specimens have been constantly submerged during the exposure to get well-defined exposure conditions. The purpose was to get a quantitative measure of how different exposure conditions influence the durability of reinforced concrete, measured in terms of chloride ingress into the concrete. The results indicate that the exposure conditions (salinity and temperature of seawater), as expected, influenced the chloride ingress. This is further analysed and discussed in the paper. (c) 2006 Elsevier Ltd. All rights reserved.
7.	Lindvall, Anders, 1971 (författare) Chloride ingress data from field exposure, at twelve different marine exposure locations, and laboratory exposure 2003 Rapport (övrigt vetenskapligt/konstnärligt)abstract Concrete specimens, made from one single concrete composition and under identical conditions, have been exposed at different exposure sites around the world. The exposure has mainly been made in marine submerged conditions, i.e. below the surface of the water, to get well-defined exposure conditions. Specimens have also been exposed in marine tidal conditions and along a thaw-salted road. Parallel with the field exposure specimens have been exposed in salt-solutions, with different chloride concentrations and temperatures, in the laboratory. Four or five specimens have been exposed on each site to get a measure of the scatter in chloride ingress. The duration of all exposures has been approximately one year.After finalised exposure the specimens have been analysed for chloride and calcium content (acid-soluble) in depth intervals from the surface. The analyses have been made on dust-samples achieved by means of profile grinding of cores drilled from the specimens. The chloride ingress has been measured as chloride ingress profiles, where the quotient between chloride and binder content is given in depth-intervals. The binder content has been estimated from the analysed calcium content, since the content of acid soluble calcium in the aggregates in the exposed concrete composition is negligible. Additionally chloride-binding isotherms (as free-bound and free-total chloride content) have been determined for the concrete composition used in the exposure programme.The measured chloride ingress profiles have been evaluated with the error-function solution of Ficks second law to derive apparent chloride diffusion coefficients, DF2, and surface chloride contents, Csa. Two additional parameters have been collected to describe non-Fickian behaviour of the profiles, thicknesses of the convection-zones (where the profiles do not fit to the error-function), xc, and surface chloride contents for the diffusion-zones, Csc. Additionally the areas below the chloride ingress profiles have been determined to get an estimate of the amount of chlorides that have penetrated into the concrete.In this report the exposure programme is summarised. The concrete specimens (concrete composition and dimensions) and the exposure locations (geographical locations and exposure conditions) are described. The measurement techniques are briefly described and the results are presented as chloride ingress profiles. Furthermore parameters evaluated from and areas below the profiles are presented. The parameters and areas have also been statistically analysed to get mean values and standard deviations.
8.	Lindvall, Anders, 1971 (författare) Chloride Ingress in a Swedish Road Environment 2002 Rapport (övrigt vetenskapligt/konstnärligt)abstract Concrete blocks have been exposed up to five winters at a field station along the motorway Rv40 west of Borås, some 60 km from the Swedish west coast. The concrete mixes are made from a number of Nordic cements and other types of binders (fly ash, silica fume and blast furnace slag) and admixtures. The concrete blocks have been periodically investigated for chloride ingress, frost and salt attack, moisture content and reinforcement corrosion. In this report the chloride ingress measured for three of the exposed concrete mixes, with w/b=0.40 and 0.75 and with an addition of silica fume, is presented. The exposure environment has been documented with data from a meteorological station at the field station together with information about spread of de-icing salt and records of water, snow and ice around the blocks.The chloride ingress is measured as chloride ingress profiles, where the quotient between the chloride and calcium content is given in depth-intervals from the surface. The results show the following:Chloride ingress during a year. There is a build up of chlorides in the concrete during a winter. The build up seems to be more rapid for vertical surfaces but the maximum ingress depths are higher for horizontal surfaces. During the summer there is a redistribution of chlorides, with a transport into the concrete and a decrease of the surface chloride content.Effect of age at the first exposure to chlorides. The age of the concrete at first exposure to chlorides seems to have a decisive effect on the achieved chloride ingress. If the concrete is young at the first exposure to chlorides the result will be a comparable higher chloride ingress, while a lower chloride ingress is achieved if the concrete is older at the first exposure to chlorides. The reason for this is probably that the pore-structure of the concrete is not fully densified, since the cement hydration has not reached its final level. The results indicate that a difference in age of one to two weeks at the first exposure to chlorides may give a significant different chloride ingress.Development in time for chloride ingress. The major part of the chloride ingress takes place during the first winter. After that only a slow increase in the chloride ingress has been observed. If an apparent diffusion coefficient, DF2, is determined special attention should be paid to the definition of the exposure time (total time or time of exposure to chlorides?).Effect of surface orientation on chloride ingress. The surface orientation (horizontal/vertical) does not seem to have any significance on the chloride ingress into concrete with low w/b (w/b=0.40). However, for concrete with high w/b (w/b=0.75) the chloride ingress and the penetration depths are higher for vertical surfaces.Effect of concrete composition. The concrete composition has a significant influence on the achieved chloride ingress, where, as expected, the w/b is the dominating factor. A low w/b gives a low chloride ingress and vice-versa. However, the effect on chloride ingress from use of silica-fume in the concrete is unclear sometimes silica-fume concrete has lower and sometimes higher chloride ingress compared to Portland cement concrete. Probable explanations could be the slower degree of reaction and lower chloride binding in silica-fume concrete compared to Portland cement concrete, which means that the age of the concrete at first exposure to chlorides is important. It is obvious that more research is needed to better explain the effect of silica-fume in concrete.
9.	Lindvall, Anders, 1971 (författare) DURACRETE - Probabilistic preformance based durability design of concrete structures 1998 Ingår i: Proceedings - 2nd International PhD Symposium in Civil Engineering. - 9634205607 ; , s. 93-99 Konferensbidrag (refereegranskat)abstract The presented project is a first attempt to make probabilistic performance based durability designs of concrete structures. The performance based durability design is based upon realistic models that describes the future behaviour of the concrete and the environment. To make calculations it is necessary to quantify the parameters included in the chosen models. In this paper two models that describes the behaviour of concrete are presented and it is shown how the environmental parameters in the models are statistically quantified.
10.	Lindvall, Anders, 1971 (författare) Environmental Actions and Response - Reinforced Concrete Structures exposed in Road and Marine Environments 2001 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract The expenses for repair, maintenance and remediation of existing concrete structures have significantly increased. A large proportion of these expenses are due to problems related to a lacking durability of the structure. Thus, to reduce these expenses it is required to make a design of the service life of the structure in which the service life is explicitly specified.In this Licentiate thesis it is described how the service life of concrete structures can be determined. The factors that have an influence on the service life of a concrete structure are described. Furthermore it is described how the service life can be mathematically modelled and which techniques that can be used to determine the service life. Three principal factors that influence the service life of a concrete structure have been identified: (1) Material properties, (2) Execution during construction and (3) Environmental actions. Lots of efforts have been made to get a better understanding of how the material properties and to some extent the execution during construction influence the service life. However, very little has been made to clarify, which influence the environmental actions has on the service life.The deterioration of concrete can be predicted with two principal types of mathematical models namely physical models, which are based on theories of transport in porous materials, and empirical models, which are based on observations from structures. A few examples of different prediction models dealing with chloride penetration, carbonation and corrosion of the reinforcement are shown. It is also briefly described how a prediction of the service life can be made, with a performance based design methodology and probabilistic methods. To achieve reliable results with these prediction models it is required to have knowledge about boundary and initial conditions, e.g. how the environmental conditions vary inside and at the surface of the structure.Predictions of the service life can be made with two different methodologies: deem-to-satisfy rules, based on rules of thumb, and performance-based design. Usually probabilistic methods are used to predict the service life in a performance based design. However these kinds of predictions require extensive statistical quantifications of the parameters in the mathematical models. These statistical quantifications require good knowledge about which parameters that influence the deterioration of concrete, e.g. concrete composition, environmental actions at the surface of the structure and/or the response from the concrete.The environmental actions on a concrete structure have a decisive influence on the service life of the structure. The description of the environmental actions can be divided into four different levels depending on the dimensional scale. The objective is to determine the environmental actions at the surface of the concrete structure in terms of temperature, humidity and chloride conditions and the concentration of carbon dioxide. Furthermore the response from the material is of interest, e.g. how moisture and temperature distributions are distributed in a concrete structure. It is described how the environmental actions at the surface of concrete structure can be derived and what the response from the concrete is described.Finally a study of the response concrete structures exposed in road environments is presented. Seven bridges in and around Göteborg, around 30 years old, have been examined to determine the chloride penetration, moisture conditions and resistance against freeze/thaw actions. The analyses have been made on cores taken from selected positions on the bridges. The results from the study show large variations in chloride penetration between the examined bridges and even on a single part of a bridge, e.g. a column. A large part of these variations are assumed to arise due to variations in environmental actions at the surface of the bridges.
11.	Lindvall, Anders, 1971 (författare) Environmental actions on concrete exposed in marine and road environments and its response - Consequences for the initiation of chloride induced reinforcement corrosion 2003 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract The object of the study presented here has been to describe, further explain and model the influence of the exposure conditions on reinforced concrete structures and the consequences on their expected service life. The focus has been on investigating and quantifying the exposure conditions for structures in marine and road conditions exposed to chloride ions. This has been done by literature studies complemented by field studies, where data on the behaviour of concrete have been gathered and analysed. The literature study has shown that the exposure conditions have a large influence, e.g. due to variations in the severity of exposure to chlorides. Field studies have been made in both marine and road conditions, where the influence of the exposure conditions has been measured as the environmental response of concrete and mortar. In marine conditions identical concrete specimens, exposed at different submerged locations, have been investigated. The results show that the temperature of the seawater has a large influence on chloride ingress. In road conditions both existing structures and specimens have been investigated. The results show that the exposure to chlorides and the chloride ingress into concrete depend on several factors, e.g. height above and distance to the road and surface orientation towards traffic. Service life predictions have been made for structures in marine and road conditions, to exemplify the effect of the exposure conditions. The results of the predictions show that the exposure conditions have a large influence on the expected service life. The predictions also showed that the level of the chloride threshold level, Ccrit, has a large influence on the predicted service life. The environmental actions, and their variations, have been found to have a large influence on the chloride ingress into and the service life of reinforced concrete structures. Therefore it is not enough to describe these by rough divisions into exposure classes, but instead the true exposure conditions should be taken into account. Preferably each structure should be treated separately, but this is usually not possible. For these structures the methodology described in this thesis can be used to describe and model the environmental actions.
12.	Lindvall, Anders, 1971 (författare) Mapping of the chloride load around two Swedish reinforced concrete bridges 2002 Rapport (övrigt vetenskapligt/konstnärligt)abstract In this report a study of the road environment around two motorway-bridges around Göteborg is presented. The study is a completion of an earlier study, made during theautumns of 1998 and 1999, where seven concrete motorway-bridges around Göteborg have been studied regarding moisture conditions, chloride penetration, frost damage andreinforcement corrosion. The results from this study show on large variations, especially in chloride penetration, both between different bridges, but also on one single bridge. The new study has been initiated to confirm and further investigate the results from this earlierstudy. The study has been carried out by exposing specimens made from mortar on bridgecolumns.The specimens are manufactured at one occasion with the same mortar composition to minimise variations in the results due to the execution and the material composition. The specimens have been exposed on two of the bridges investigated in the earlier study. Two bridges are bridge O 951, which is situated along the motorway E6 some 20 km south of Göteborg, and bridge O 978, which is situated along the motorway Rv40 some 15 km east of Göteborg. The exposure, made at different heights over the roadways and orientations towards the traffic, was started in the middle of February 2001, and was finished in the middle of May 2001. After finalising the exposure, the chloride penetration into each specimen has been determined by profile grinding in depth intervals and wet chemical analysis of the powder samples to determine the chloride and calcium content. The chloride penetration is presented as chloride penetration profiles where the quotient between the chloride and calcium content at different depths is presented.The results from the study show that the exposure for chlorides varies a lot depending on the height over the roadway and the orientation towards the traffic. The exposure for chloride was found to be largest for surfaces orientated towards the traffic on the same level as the roadway. Since de-icing salt normally is spread during the night or early in the morning, this means that surfaces that faces towards the morning traffic has the highest exposure to chlorides. This effect can be observed on bridge O 951, with marked commuter traffic to and from Göteborg, where the surface that faces towards the traffictowards Göteborg has significantly higher exposure for chlorides compared to the other surfaces. On bridge O 978, with less commuter traffic, this variation in exposure tochlorides cannot be observed. Furthermore, large chloride penetration was observed up to two meters above the roadway on bridge O 978. A possible explanation for this is adeposition of airborne chlorides at certain wind-directions on the lee-side of the column. This surface is not exposed to rain, that will wash the chlorides away, which means thatthe chlorides will be accumulated in the concrete. These results confirm the results from the study made during the autumns of 1998 and 1999.
13.	Lindvall, Anders, 1971 (författare) Mapping the chloride load around two Swedish reinforced concrete bridges - second season 2004 Rapport (övrigt vetenskapligt/konstnärligt)abstract In this report a study of the road environment around two motorway bridges situated outside Göteborg is presented. The road environment has, in this study, been described in terms of exposure to chlorides on the examined bridge structures. The study is a follow-up of two earlier studies, where both the exposure to chlorides on structures and the chloride ingress into concrete have been studied. The results from these earlier studies show on large variations in both the exposure to chlorides on the structures and chloride ingress into the concrete. Therefore this new study has been initiated to further investigate the exposure conditions for the examined motorway bridges.The exposure to chlorides on a specific structure is influenced by several factors, e.g. height over and distance to the roadway, surface orientation towards traffic, weather conditions and characteristics of road, spread of de-icing salt and traffic etc. In this study, however, the focus has been on the significance of the height over the roadway and the orientation towards traffic together with the characteristics of the traffic and spread of de-icing salt.The study has been carried out by exposing mortar specimens, with similar mortar composition, on selected positions on bridge columns. The examined bridges have been bridge O 951, situated along the motorway E6 some 20 km south of Göteborg, and bridge O 978, situated along the motorway Rv40 some 15 km east of Göteborg. The mortar specimens have been exposed on different heights above the roadway and orientations towards the traffic. The exposure started in the beginning of December 2001 and ended in the middle of April 2002. After finalised exposure the mortar specimens have been analysed for chloride ingress in depth intervals.The results from study show that the exposure to chlorides on a structure depends both on the height over the roadway and orientation towards the traffic. Fairly large variations in exposure to chlorides on a structure were, however, observed both between the bridges but also within one single bridge. The exposure to chlorides on structures generally decreases with increasing height over the roadway. This effect, however, was only observed on one of the examined bridges, while no effect was observed on the other. The exposure to chlorides has also been found to depend on the orientation towards the traffic, where surfaces facing towards the traffic have more severe exposure than surfaces facing from the traffic. The effect from orientation towards the traffic has been observed up to 3 meters above the roadway.The exposure to chlorides on structures, measured in this study, has been compared with similar measurements made on the same bridges but during another winter season. This comparison shows that it seems not possible to directly compare severities in exposure to chlorides, measured during different winter seasons. The exposure to chlorides on structures has also been compared with chloride ingress measured in the concrete. This comparison shows large deviations between the exposure to chlorides on structures and the actual chloride ingress into concrete, e.g. that spots with severe exposure to chlorides have small chloride ingress and vice versa. The reasons for these observations are not known, but anyhow they show that it is difficult to correlate data on the exposure to chlorides, measured after exposure during only one winter season, with data on the actual chloride penetration into the concrete, following from exposure during several years. The comparison indicates that there are also other factors, which have significant influence on the exposure to chlorides on the structure, e.g. direction of commuter traffic and airstreams around the structures. Thus, it is not trivial to describe and quantify the exposure conditions for bridges situated along thaw-salted roads. The overall conclusion from the study is therefore that preferably each bridge should be treated separately when the exposure conditions are described and quantified.
14.	Lindvall, Anders, 1971 (författare) Models for environmental actions for reinforced concrete structures in marine and road environments 2006 Ingår i: International conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR), 21-23 November 2005, Cape Town. - 0415396565 ; , s. 119-120 Tidskriftsartikel (refereegranskat)abstract In this paper models for environmental actions on reinforced concrete structures exposed tochlorides are proposed. The models are based on the DuraCrete chloride ingress model and in the paper they arebriefly presented and examples are given of how some of the parameters in the models can be quantified.Service life predictions have been made to exemplify how the models for environmental actions influence theservice life for reinforced concrete structures in different marine exposure conditions. The results from the servicelife predictions show the consequences of the modelling of the environmental actions in these exposure conditions.They also show on the possibilities to optimise the design of reinforced concrete structures exposed indifferent exposure conditions with respect to durability. This can be made for example by appropriate choicesof concrete compositions and covers based on the service life predictions.
15.	Lindvall, Anders, 1971 (författare) Performance and properties of concrete in diaphragm walls - Swedish Experiences 2007 Ingår i: Proceedings of the 5th International Conference on Concrete Under Severe Conditions - Environment and Loading. - 1628-4704. ; 1, s. 205-212 Konferensbidrag (refereegranskat)abstract Diaphragm walls are a type of geotechnical structures, which mainly are used to stabilize deep excavations built in densely populated areas. The most common type of diaphragm walls are cast in-situ in submerged conditions in a support liquid used to stabilize the excavation. There are concerns that the construction method may negatively influence the properties of the finalized structure. However, up to now little research has been done regarding the significance of this influence. Therefore during the last years in Sweden two recently constructed diaphragm walls have been investigated. In this paper some results from these investigations are presented. The results show that there is only a slight negative influence on the properties of the concrete in diaphragm walls compared to conventional structures.
16.	Lindvall, Anders, 1971, et al. (författare) Probablistic service life design for concrete structures in marine and road environments 2006 Ingår i: European Symposium on Service Life and Serviceability of Concrete Structures, ESCS-2006. ; , s. 220-226 Konferensbidrag (refereegranskat)abstract Reinforcement corrosion initiated by chlorides is one of the most common causes for limitation of the service life of reinforced concrete structures. Traditionally the design aspects of durability of concrete structures have been dealt with using so-called deem-to-satisfy approach, which usually results in a sufficiently long but not specified service life. Therefore during the last decades methods have been developed, which make explicit predictions of the service life. Normally deterministic data have been used in these predictions, which mean no consideration is given to the uncertainties in influencing factors. Instead probabilistic methods should be used, where uncertainties are included. In this paper probabilistic service life designs are made for concrete structures exposed in saline environments. Three different mathematical models have been used to make predictions, namely the Error-function, DuraCrete and ClinConc models.
17.	Lindvall, Anders, 1971, et al. (författare) Undersökning av kloridinträngning, armeringskorrosion, frysning och fukttillstånd på sju brokonstruktioner exponerade för tösalter 2000 Rapport (övrigt vetenskapligt/konstnärligt)abstract I följande rapport presenteras en studie av fukttillstånd, kloridinträngning, frostbeständig-het och tröskelvärden för armeringskorrosion gjord på sju vägbroar belägna i Storgöte-borg.Studien har utförts under hösten 1998 och hösten 1999. De undersökta broarna är mellan 26 och 32 år gamla och både kantbalkar och pelare har undersökts. Broarna har valts ut i samråd med Vägverket och studien har genomförts så att broarna inte skadats, t.ex. har nästan ingen armering borrats av. På broarna som undersökts under hösten 1999 har en eller två pelare på samma bro undersökts på olika höjder över och orienteringsriktningar mot trafiken.Fukttillståndet i de undersökta broarna har bestämts som relativ fuktighet, RF, och kapillär mättnadsgrad, KMG. En betongkonstruktion exponerad i en vägmiljö kan delas in i en torr och en våt zon. I den torra zonen finns de delar av konstruktionen som är skyddade mot nederbörd, t.ex. pelare, och i den våta zonen finns de delar av konstruk-tionen som är oskyddade mot nederbörd, t.ex. kantbalkar. Analysen av fukttillstånden i de undersökta broarna visar att det finns en viss skillnad mellan fukttillståndet i den torra respektive våta zonen. Tillsammans med information om betongens sorptionskurvor kan det konstateras att det i de torra zonerna sker en uppfuktning medan i de våta zonerna sker en uttorkning vid provtagningstillfällena.Analysen av kloridtillståndet visar att det finns stora variationer i kloridinträngning i kantbalkar och pelare både mellan olika broar men också på en enda bro. En stor del av dessa variationer kan förmodligen förklaras med variationer i exponeringsmiljön och betongkvalitet. Variationer i kloridinträngningen beroende på höjd över vägbanan och orienteringsriktning mot trafiken har konstaterats. Resultaten från studien tyder på att det inte finns någon större skillnad i kloridinträngning mellan horisontella och vertikala ytor på kantbalkar. Dock har stora variationer observerats mellan olika broar. Vidare har ingen effekt konstaterats från hastighetsbegränsningen på vägen på kloridinträngning i kant-balkar. Vid en jämförelse mellan en kantbalk och en pelare exponerade längs samma väg observerades att kloridinträngningen var störst på de ytor på pelaren som vetter mot trafiken, därefter kantbalken och slutligen de ytor på pelaren som vetter från trafiken.Frostbeständigheten har undersökts på fyra av broarna enligt SS 13 72 44 (Borås-metoden). Både ytterytor och inre sågade ytor på utborrade kärnor har undersökts. Resultaten visar att frostbeständigheten är god för samtliga uttagna prover utom för den inre delen av betongen på en av broarna.Ett av syftena för den genomförda studien har varit att undersöka tröskelvärden för armeringskorrosion. Om armeringen korroderar eller inte har undersökts visuellt, t.ex. om det finns rostfläckar eller sprickor på betongytan. Armeringskorrosion har inte konstateras på någon av de undersökta pelarna eller kantbalkarna. Endast på undersidan av brobane-plattan på en av broarna (täckskikt på ca 22 mm och kloridkoncentration på ca 1,5 vikt-% av CaO ca 0,9% av cementvikten) har korrosion konstaterats. Exponeringen för klorider har skett genom läckage av kloridhaltigt vatten från vägbanan genom en övergångs-konstruktion mellan två brobaneplattor. I samband med provtag-ningen observerades också skador på översida av pelare och rullager under övergångs-konstruktionen. Läckage av kloridhaltigt vatten genom övergångskonstruktionen är förmodligen orsakat av bristfälligt underhåll av bron. Tröskelvärdet för kloridinitierad armeringskorrosion har konstaterats att ligga mellan ca 1,0 vikt-% (ingen korrosion konstaterad) och 1,5 vikt-% (korrosion konstaterad) av CaO, d v s ca 0,6% till 0,9% av cementvikten.Inverkan av hydrofobering av betongen har studerats på två broar. Resultatet tyder inte på att det finns någon signifikant skillnad på kloridinträngningen mellan betong som är hydrofoberad respektive ej hydrofoberad. Dock kan hydrofobering ha effekt på fukttillståndet i konstruktionen. Detta har inte undersökts i studien.Slutsatser som har dragits av den genomförda studien är att det är svårt att på ett enkelt sätt att systematisera mätningar av kloridinträngning i betongbroar. Stora variationer i kloridinträngning har observerats både mellan olika broar men också på en enda bro. Exponeringsmiljön för konstruktionen har stor inverkan på kloridinträngningen och det är därför viktigt att ha kännedom om denna. Korrosionsskador har observerats endast på konstruktionsdetaljer där dåligt arbetsutförande eller underhåll konstaterats. Tillsammans med arbetsutförande och underhåll har mikroklimatet en avgörande inverkan på hur god beständigheten för betongen blir. Vid en tillståndsbedömning är det alltså viktigt att identifiera de delar av en bro där mikroklimatet är aggressivt och eventuella brister i arbetsutförande samt underhåll kan finnas.Framtida undersökningar som föreslås är att ytterligare utreda vilka effekter avstånd till och höjd över vägbanan samt orienteringsriktning mot trafiken har på kloridinträng-ningen. Ett lämpligt objekt för en sådan studie är en bro som skall rivas, där prover kan tas utan hänsyn till säkerhet för konstruktionen och om givande trafik. Vidare föreslås att ytterligare studier görs av vilken inverkan arbetsutförande och underhåll har på klorid-inträngning och fukttillstånd. Det viktigaste är dock att få ett underlag för att säkrare kunna förutsäga hur stor kvarvarande livslängd en bro har. De undersökta broarna är 26-32 år gamla och kloridinträngningen har ännu inte initierat någon armeringskorrosion i riktigt utförda delar. Det finns idag inte tillräckligt underlag för att förutsäga om armeringskorrosion startar inom t.ex. tio år eller om broarna kanske har 100 års kvarvarande livslängd.
18.	Lövgren, Ingemar, 1972, et al. (författare) Predicting chloride induced depassiviation and minimum concrete cover with different binders 2016 Ingår i: Materials, Systems and Structures in Civil Engineering 2016 - Segment on Service Life. 1. - 9782351581704 ; 1, s. 155-164 Konferensbidrag (refereegranskat)abstract Corrosion of steel reinforcement represents the major cause affecting durability of reinforced concrete structures in road and marine environments. To assure durability, standards attempt to provide specifications for long-term performance by simple deemed-to-satisfy rules for approximate environmental classification. This paper presents results from a study of modelling of chloride ingress in concrete with fly ash and ground granulated blast-furnace slag. Chloride threshold values for corrosion initiation are discussed. A physical model, ClinConc, was employed to calculate the chloride ingress profiles after exposure under marine (submerged) and road environments for 100 years. The model was validated using field data after exposure in the Swedish seawater for about 20 years. The results show that the addition of mineral additions in general increases the resistance of concrete to chloride ingress and allows smaller concrete cover thicknesses. However, one critical parameter is the chloride threshold value. In consideration of both the chloride resistance and the alkalinity, which influence the critical chloride threshold value, the concrete with mineral additions still reveals sufficient margin to allow a significantly lower chloride threshold for initiation of corrosion of reinforcement steel in concrete.
19.	Lövgren, Ingemar, 1972, et al. (författare) The influence of carbonation and age on salt frost scaling of concrete with mineral additions 2016 Ingår i: Materials, Systems and Structures in Civil Engineering 2016 - Segment on Frost Action in Concrete. - 9782351581827 ; , s. 91-100 Konferensbidrag (refereegranskat)abstract Resistance to salt frost scaling is tested by accelerated methods such as CEN/TS 12390-9 which originally were developed for Portland cement concrete. However, it has been shown that ageing and coupled deterioration mechanisms, like carbonation or leaching, alter the frost resistance. An example is concrete with high amount of slag where the frost resistance is reduced when the concrete is carbonated. Hence, modifications to the test methods have been proposed to take these effects into account and often an accelerated carbonation at an early age have been used. Though, it has been found that the accelerated tests show a much more negative effect than what is experienced in field conditions. This paper presents results from a laboratory study of concrete with mineral additions at different dosages and water/binder ratios which have been exposed to accelerated carbonation at 1% CO2-concentration at different ages. The results show that exposing the specimens to accelerated carbonation at a young age will result in an increased scaling but that the carbonation depths corresponds to 10 year natural exposure. By increasing the age before the accelerated carbonation exposure the scaling is significantly reduced and the salt frost scaling resistance seems to correlate better with field observations.
20.	Tang, Luping, 1956, et al. (författare) Durability of Concrete in Marine Environment - Over 10 Years' Traceable Evaluation of Chloride Ingress 2006 Ingår i: 2nd fib Congress June 5-8, 2006 - Naples, Italy. - 8889972068 ; 2, s. 476-477 Konferensbidrag (refereegranskat)abstract This paper intends to express the physical model ClinConc in a more engineer-friendly way. Through the numerical evaluation it has been found that there exist good correlations between the time-dependent factors for chloride binding and for diffusion coefficient, and between the laboratory measured diffusion coefficient and the apparent one, the latter is a result of the combined effects of material properties and environmental actions. Therefore, the ClinConc model can be expressed by the similar error function as used in many empiric models, but with the proper physical procedures, that is, modeling free chloride transport taking free chloride as diffusion potential and then calculating the total chloride content taking into account the non-linear chloride binding. The modeled chloride profiles are in good agreement with the measured ones, even though further study is needed to clarify the expansion coefficient for the concrete containing silica fume and other pozzolanic additions.
21.	Tang, Luping, 1956, et al. (författare) Prediction of Chloride Ingress into Concrete - Verifications from the Field Exposure 2006 Ingår i: European Symposium on Service Life and Serviceabiliy of Concrete Structures. ; , s. 68-73 Konferensbidrag (refereegranskat)abstract This paper presents the verification results from four prediction models for chloride ingress in concrete: 1) the simplest error function solution to Ficks second law (Model 1); 2) the DuraCrete model (Model 2); 3) a mathematically improved DuraCrete model (Model 2b) and 4) the mechanism-based model ClinConc (Model 3). Chloride profiles taken from 10 types of concrete from the field exposures are used to verify these models. The concrete compositions include Portland cement and blended with pozzolanic additives (silica fume, fly ash and their combination), with water-binder ratios from 0.25 to 0.40. The results show that the mechanism-based model ClinConc reveals good prediction for all the cases. The model using simplest error function to Ficks second law significantly overestimates chloride ingress. The DuraCrete model in most cases underestimates chloride ingress, especially for the concrete with pozzolanic additives, due to its oversimplified mathematic expression in dealing with the age factor for chloride diffusion coefficient. The results suggest that care must be taken when using empiric models for service life prediction, because the actual chloride ingress in concrete with silica fume and fly ash after 10 years field exposure has in some cases already exceeded the 100 years prediction made by the DuraCrete model.
22.	Tang, Luping, 1956, et al. (författare) Validation of models and test methods for assessment of durability of concrete structures in the road environment 2012 Rapport (övrigt vetenskapligt/konstnärligt)abstract This report presents the results from validation of models and test methods for assessment of durability of concrete structures exposed in Swedish road environment. In the past years a number of models for durability design of concrete structures have been suggested by relevant organisations or international committees. It is necessary to validate these models against long-term field data for their applicability with respect to exposure climate in order to satisfactorily use the models in the durability design and redesign of concrete structures. In this study, various potential models for concrete resistance to chloride ingress, carbonation and frost attack were compiled and the sensitive input parameters that affect the modelling results were mathematically analyzed. Three models including the simple ERFC, the DuraCrete and the ClinConc, for prediction of chloride ingress were evaluated using the infield data collected from both the field exposure site after over 10 years exposure and the real road bridges of 25-30 years old. A physicochemical model for prediction of carbonation depth was evaluated using the infield data collected from the field exposure site after 11 years exposure and the limited data from the real structures with the age of 7-13 years. The results from different standard test methods including the newly standardised prEN/TS 12390-11 for chloride diffusivity were compared. For the modelling of frost attack, some test procedures for measurement of critical saturation degree and water absorption curves including the pump effect were suggested. Based on the results, recommendations as guidelines for practical application of test methods and models in durability design of concrete structures were suggested.
23.	Tang, Luping, 1956, et al. (författare) Validation of models for assessment of durability of concrete structures exposed in the chloride road environment 2010 Ingår i: Advances in Concrete Structural Durability, ed by H. Yokota, T. Sugiyama and T. Ueda, Hokkaido University Press. - 9784832903609 ; , s. 293-302 Konferensbidrag (refereegranskat)abstract This paper presents validation of models for assessment of durability of concrete structures exposed in the chloride road environment. In the past years a number of models for durability design of concrete structures have been suggested by relevant organisations or international committees. It is necessary to validate these models against long-term field data for their applicability with respect to exposure climate in order to apply the models in the durability design and redesign of concrete structures. In this study, three models including the simple ERCF, the DuraCrete and the ClinConc, were evaluated using the measurement data collected from both the field exposure site after over 10 years exposure and the real road bridges of 25-30 years old. The sensitivity of input parameters in each model is analysed. The results show that, among different input parameters, the age factor n is the most sensitive one. The simple ERCF-model significantly overestimates chloride ingress. The DuraCrete model, if the input parameters are properly selected, may give a reasonably good prediction, otherwise often underestimates chloride ingress. The ClinConc model in general gives fairly good predictions for chloride ingress in de-icing salt road environment with heavy traffic at high speed.
24.	Tang, Luping, 1956, et al. (författare) Validation of models for prediction of chloride ingress in concrete exposed in de-icing salt road environment 2013 Ingår i: International Journal of Structural Engineering. - 1758-7328 .- 1758-7336. ; 4:1-2, s. 86-99 Tidskriftsartikel (refereegranskat)abstract This paper presents the results from validation of models for prediction of chloride ingress in concrete exposed in de-icing salt road environment. Three models including the simple error-function complement (ERFC) model, the DuraCrete model and the ClinConc model, were evaluated using the measurement data collected from both the field exposure site after over ten years exposure and the real road bridges after 25-30 years in service. The sensitivity of input parameters in each model is analysed. The results show that, among different input parameters, the age factor is the most sensitive one. The simple ERFC model significantly overestimates chloride ingress. The DuraCrete model, if the input parameters are properly selected, may give a reasonably good prediction, otherwise often underestimates chloride ingress. The ClinConc model in general gives fairly good predictions for chloride ingress in de-icing salt road environment with heavy traffic at high speed.
25.	Westerberg, Bo, et al. (författare) Vägledning för livslängdsdimensionering av betongkonstruktioner 2007 Rapport (övrigt vetenskapligt/konstnärligt)

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