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Post-cast application of hydrophobic agents onto hardened concrete is successful at reducing external ion diffusion into cement paste, this work examines pre-cast application of hydrophobic admixtures in fresh concrete. Concretes, with water to cement ratios (w/c) 0.45 and 0.50 (CEM I; low C3A), were mixed. Adding alkyltrialkoxysilane or triacylglycerol admixtures ranging from 1 to 3 wt%cem in these concretes were evaluated. Increasing the dosage of hydrophobic admixtures decreased the compressive strength. The usage of these admixtures did not hinder the further development of the microstructure as all concretes gained strength after one year, but not in the same percentage increase as the reference concrete. Chloride ion diffusion, after exposure to 3 wt% NaCl solution at 20 °C for 91 days, in concretes with 1 wt%cem admixture showed slight reductions in diffusion rate (8-17%) compared to the reference. At 3 wt%cem, triacylglycerol admixtures showed better hindering effects of inward chloride diffusion, this was especially evident in w/c = 0.45. Equivalent addition of alkyltrialkoxysilane-based admixtures increased the diffusion of chloride ions transferred into the cement matrix., QC 20230405

QC 20221025

Rapporten innehåller rekommendationer och riktlinjer rörande alkalisilikareaktioner (ASR) i betong och ska betraktas som en vägledningsrapport. Vägledningen har förslag på hur man kan förhindra ASR för nyproducerad betong och vilka åtgärder som finns för befintliga konstruktioner som påverkats av ASR. Dessutom finns information om ASR som fenomen och hur sprickbildning i betong påverkas av ballastmaterial, cement, tillsatsmaterial och armering. Fokus har också riktats mot aktuella frågor som berör en hållbar utveckling. Inte minst gäller det att underlätta utnyttjandet av material på ett resurseffektivt sätt, tex. genom att använda lokala material i större utsträckning eller entreprenadberg från tunneldrivning och vägbyggen i ny betong utan att kvaliteten äventyras. Syftet har varit att främja god hushållning med material, råvaror och energi i enlighet med Miljöbalkens 1:a kapitel, § 1. När det gäller nyproduktion av betong lämnas förslag på en för Sverige gemensam kvalitetssäkring som innehåller analys och provning av ballast, gränsvärden för godkännande av ballast samt provningsmetodik för godkännande av tänkbara materialkombinationer av ballast och cement (se Bilaga A – Rekommendationer för undvikande av ASR i betong). Bakom förslaget ligger en hel del utvecklingsarbete från provning av olika ballasttyper från hela landet som kombinerats med olika cementsorter och alkalihalter. Arbetet som fortfarande pågår, kan innebära en revidering av den här föreslagna accepterade alkalinivån i betong med ballast som inte behöver genomgå provning (för närvarande 3,0 kg alkali/m3 betong). Det förslag på kvalitetssäkring som finns beskriven i Bilaga A innebär ett provningsschema som i olika steg kan godkänna eller underkänna ett ballastmaterial eller en cement-ballast kombination. Meningen är att relevanta förslag i rapporten ska kunna implementeras i den svenska tillämpningsstandarden för SS-EN 206 som är SS 137003. Det har saknats rekommendationer och riktlinjer för vad som s, Hållbart samhällsbyggande med beständig betong, Alkaliesilikareaktioner i betong (ASR)

As part of a report [1] on continuous preventive bridge maintenance, a survey was conducted with Swedish municipalities. The survey’s focus was on bridges and preventive maintenance, as well as the demands and performance control stated by the municipalities. The preventive maintenance the survey focused on was the annual maintenance concerning washing, cleaning of drainage system and removal of vegetation. The survey showed both similarities and differences within the municipalities but also in comparison with Swedish Transport Agency (STA)., QC 20190107

Vidhäftningsskador hos asfalt i form av avskalning av bitumen från ballast kan uppkomma genom att vatten tränger undan bindemedlet från ballastytan. Vidhäftningen, interaktionen mellan bitumen och stenmaterial beror på kemisk attraktion och fysikalisk kontaktyta. Projektet går ut på att undersöka vilka egenskaper som särskiljer olika materials påverkan på vidhäftningsegenskaper genom att samla in stenmaterial med stor naturlig variation sinsemellan som finns på marknaden idag. Bitumen har ett internationellt ursprung, där endast en del av dessa finns på svenska marknaden idag. Bitumen och ballast har karakteriserats. Permitivitet, ytenergier och funktionella grupper har fastställts på bindemedlen. Mineralinnehåll, bergart, känslighet för ASR, specifika ytor och porstorlekar bestämdes på ballasten. Bitumen med penetrationstal 20/30,50/70,70/100 och 160/220 och åtta vanligt förekommande ballastmaterial samt kalksten och slagg är inkluderade i denna studie. Undersökningen visar att: Man kan dela upp bitumenmaterialet i två olika grupper med avseende på dielktriskt förlustvinkel, ytenergi och förekomst av kolväte. det har inte gått att påvisa några signifikanta variationer i dielktricitetskonstanten mellan olika bitumenmaterial. Slagg och kalk har flera gånger så stor specifik yta som ballastmaterialen från täkterna inklusive kvartsiten. Dessa resultat kan förklaras med att ytstrukturen hos slagg och kalk är annorlunda än den för ballastmaterialen och kvartsite. Ett av ballastmaterialen visade en avvikande specifik yta hos finpartiklarna vid en jämförelse med övriga ballastmaterial. För att kunna korrelera resultaten i i denna rapport mot idag tillgängliga metoder för att mäta vidhäftningsegenskaper hos asfaltmassa föreslås att även etapp C genomförs., Se bilaga "Vidhäftningsegenskaper i asfaltbeläggningar, undersökning av 10 stenmaterial och 2 bitumen med vändskak och rullflaskemetoden" från PEAB., Implementering av metod för mätning på bitumen, sten och findel för optimerad vidhäftning och fuktstabilitet i asfalt

QC 20181214

QC20100714

QC 20221004

QC 20110211

QC20100715

QC 20101129

Water repellent agents are used on concrete to change the conditions for moisture transport and fixation and thereby protect the concrete and the reinforcement bars from, e.g., chlorides, frost damage and alkali silica reactions. The most frequently discussed topic regarding water repellent treatments is the penetration depth of the agent. What is required and what is needed to achieve it? The effective penetration depth of a water repellent agent is defined as the distance from the surface to the sharp line between dry and wet concrete after it has been sprayed with water. During the past decade several papers have been published where factors having a major influence on the penetration depth for different water repellent agents have been investigated. The conclusions that can be drawn from these papers are that the three most important factors are time, porosity and degree of saturation. The time referred to is the duration of contact between the water repellent agent and the concrete surface. The porosity and degree of saturation refer to the concrete pore system and the amount of moisture inside the concrete at the time of the impregnation. There is, however, a lack of investigations quantifying the influence of these factors. This paper presents an empirical equation that gives an idea on how much these factors affect the efficient penetration depth of the water repellent agent. The equation is based on 300 new tests described and analysed in the paper. It is clear that the polymerisation rate of the water repellent agent affects the penetration depth. A fast reaction has the effect of slowing down the penetration., QC20100714

In order to understand the mechanisms of water repellents it is important to have reliable data on how the moisture diffusion coefficient is affected by a hydrophobic treatment. The results from the experiment described below will be used as input data in a project aiming to create a computer model for simulations of moisture and material transport in impregnated concrete structures. Two types of concrete with wo /c = 0.8 and 0.45 have been investigated by means of the cup-method to determine the moisture diffusion coefficient. Half of the specimens have been completely impregnated with trietoxy(isooctyl)silane by capillary suction and the other half were left untreated. This silane is one of the most common used water repellents on the Swedish market. Four different saturated salt solutions are used to create a relative humidity (RH) between 85 % and 97 % inside the cups while the surrounding environment is kept at 50 % RH. Three cups for each situation, two cups with pure water and four cups for verification give a total of 54 cups. The weight of the cups has been monitored weekly until a constant weight loss per unit time is obtained. With the use of Kirchhoff's potential in the calculations, the cup method is an efficient way of measuring the moisture diffusion coefficient. The moisture diffusion coefficient for treated concrete is found to be close to constant and less influenced by the RH compared to untreated concrete. Further, the results have shown that the transport of water vapour is highly reduced after a water repellent treatment. The accuracy of the method is verified at conditions of low humidity and a one dimensional steady state flow., QC20100714

Which repair material should be chosen and how to use it are questions that have arosen because of earlier unsuccessful concrete repairs. Several investigations [l-31 stress that the compatibility between the repair material and the old concrete is important, in order to achieve a successhl concrete repair. The lifetime of a concrete construction can be optimised if the repair is done in the right moment and with a correct technique. Costs and natural resources can also be saved with optimal repairs. With thorough investigations and studies of the transition zone between repair material and old concrete and studies of different repair materials understanding for mechanisms and parameters that affect the lifetime of the repair can be achieved. This investigation is a pilot study to the PhD project 'Characteristics of the repair material and the transititon zone between repair material and old concrete'. The objective of this pilot study is to collect existing knowledge and experience by interviewing people working in the area of concrete repairs at SNRA, Swedish National Road Administration, and SNRaA, Swedish National Rail Administration. In order to achive a more complete picture of the repair strategies currently used in Sweden interviews with material producers, contractors and repair consultants were also carried out. The conclusions from these interviews and suggestions for areas that need hrther investigation and research are presented in this paper. The interviews were complemented by a literature review. The whole pilot-study is presented in 'CBI-commision report 2004-56', [4], and was financed by SNRA, SNRaA and CBI., QC 20101129

QC 20101129

Moisture is the source of most damage in concrete bridges, such as frost damage and reinforcement corrosion. Experiments and field investigations show that impregnation with silanes and siloxanes provide good protection against moisture for at least eight to ten years. But most of the research only verifies this without providing a reason for the positive results. This project analyses how common impregnation substances work in concrete. Additionally, the authors develop models in order to explain these effects. As a first step, it is important to obtain reliable data on how the moisture diffusion coefficient is affected by hydrophobic treatments. Some of the factors investigated are how the water-cement ratio and the impregnation depth will influence moisture transport. One of the goals is to create a computer model to predict the moisture and chloride content over time when the geometry, the material properties of the concrete structure and the environmental conditions are known., QC 20101117

NQC

QS 20120327