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<p>The sealing of hard jointed rock by grouting involves several complicated mechanical systems. The result is a complex coupled system of hydro- logical and mechanical precesses. In order to determine the higher order effects of the resulting system the fracture deformations must be assessed. This requires a model that mimics the mechanical behaviour of not only fractures under normal load but also the entire rock mass system. This model indicates that there are two dominant regimes involved; a permeation regime and a high pressure regime.</p><p>The pressure limit that separates permeation grouting from high pressure grouting can then be found to be closely related to the in situ stress. In the high pressure regime the deformations may be large but very situation-dependent. The principal deformational eigenmodes of some boundary conditions are considered. The analysis indicates that the usage of high pressure grouting can be both benficial to the operation as well as increase the inflow of water to the excavation.</p>

<p>Water repellent agents, today mainly consisting of alkylalkoxysilanes, are often used on concrete to prolong the service life of the structure. This is accomplished by protecting the reinforcement bars from chlorides or by changing the moisture content inside. When the concrete is treated with a water repellent agent the properties of the surface layer turn from hydrophilic to hydrophobic and thereby water droplets are stopped from entering, still allowing water vapour to pass through. This property change can reduce chloride ingression and stop heavy rain from penetrating through the surface layer.</p><p>This thesis presents results concerning how the moisture transport and fixation in the surface layer of the concrete is affected by a water repellent treatment. It also presents an investigation in which the effective penetration depth and the factors that influence it are studied. The methods used covers uni-dimensional transport of moisture using the so called cup method, measurements on moisture fixation using climate boxes with saturated salt solutions, penetration depth by cracking samples and spraying water on them, and field tests in a harsh tunnel environment.</p><p>The moisture diffusion coefficient for a water repellent treated concrete is close to constant and not nearly as dependent on the relative humidity (RH) as for untreated concrete. Unlike untreated concrete, where capillary suction plays an important role for the moisture transport at high RH, the vapour transport is the dominant transport mechanism even at high RH for water repellent treated concrete.</p><p>The moisture fixation is affected by a water repellent treatment and the effect is clearest at high moisture levels. There is, however, a certain amount of moisture present in a concrete treated with a water repellent agent. It can also be seen that the main reason for this is that the capillary porosity is affected by the treatment to a relatively high degree while the gel porosity to a large extent remains unaffected.</p><p>The three most important factors for the penetration of any water repellent agent into concrete is time, porosity and degree of saturation. An empirical equation is derived that gives an idea on how much these factors affect the efficient penetration depth of the water repellent agent.</p><p>Measures prolonging the service life of a concrete structure will lead to savings of natural resources and thus both economical and environmental savings for the community. The aim with the PhD-project is to develop explanation models to the promising results that have been obtained from the empirical research during the last decade and by doing this also create a better knowledge about when and how to apply a water repellent agent in order to benefit as much as possible from the product. The results presented in this Lisenciate thesis will be used as input in these models in the planned second phase of this project.</p>

<p>New road infrastructure projects are important and constitute of large investments that have to serve the society for a long time. The investments have to be durable at the lowest life cycle cost and the pavements have to sustain loads from increasing traffic intensity and heavy traffic loads. In Sweden less than 1 ‰ of the national road network consists of concrete pavements. In parts of Europe and in the U.S., on the other hand, concrete roads are used to a large extent for highways as well as rural roads. To encourage the competition between different road materials in Sweden, the tools for designing robust concrete pavements have to be brought forward. In order to emphasize plain concrete pavements as an alternative in road construction, the design must also be competitive.</p><p>The current Swedish design method for concrete pavements is straightforward but offers no flexibility when designing roads with, for instance higher traffic loads. The method calculates concrete thicknesses on the conservative side since only a limited number of parameters are treated. Modern methods that take into account many more parameters in the design are being developed internationally. For a new Swedish design method, these parameters have to be established for actual conditions in Sweden. Also, the design has to be flexible and meet the demands from contractors and clients for a wider use.</p><p>The aim of this project is to develop a new design method for plain concrete pavements that is more flexible than today. A new design method is also intended for the Swedish Road Administrations’ (SRA) computer based public design guide, PMS Objekt.</p><p>Information for a new design method has been assembled mainly by investigating two newly developed design methods, VENCON2.0 in the Netherlands, and the Mechanistic-Empirical Pavement Design Guide (MEPDG) in the USA. Comparative calculations between the Swedish design method and the MEPDG are presented. The comparison is made on the level of input parameters and highlights the advantageous aspects of a semi-mechanistic design procedure where the functional properties of a concrete pavement are calculated incrementally over the design period.</p><p>Plain and lean concrete, separately, but also the in composite beams, have been studied in flexural fatigue testing. The results show that Tepfers’ fatigue criterion is valid for both plain and lean concrete when subjected to flexural fatigue loading. The results also show that the fatigue strength of composite beams of plain and lean concrete is mainly dependent on the strength of the lean concrete but that Tepfers’ fatigue criterion is applicable. The bond between plain in lean concrete is found to be strong and fatigue resistant, making the composite section able to accommodate higher stresses. The bond nevertheless contributes to the risk for reflection cracks in the plain concrete wear layer and a recommendation to focus on stresses in the bottom of the lean concrete is formulated. Also, well distributed expansion joints in the lean concrete are necessary.</p><p>A new project for measuring temperature gradients for use in concrete pavement design is also presented. This is done with means of concrete prisms placed in the pavement and are done in order to establish actual temperature gradients for various locations in Sweden. Also, the nonlinear gradients that act in the pavement as well as the negative temperature gradients will be analysed for the use in the design.</p><p>Finally, the thesis outlines a new design method for Swedish conditions. The method is possible to develop gradually and is based on FE-analysis for fast computations. In the design, stresses from traffic and temperature loads are calculated simultaneously in a number of critical locations in the concrete slab. The method will also make it possible to alter design features as slab lengths and widths, with various connections between the slabs. </p>

<p>Production of one family houses has over time developed successfully in Sweden and producers have managed to reduce the production costs and industrialize the production process. The development has however not been that successful when it comes to high-rise buildings. There are many attempts made, but no one has really managed to create a product that can persuade the market. The systems used are not flexible and cannot cope very well with variations in the design. The aim of this work has been to develop and evaluate the idea of prefabricated high-rise buildings within the outlines of a scientific research. By understanding the problems that the building sector experiences today it will be possible to identify the solutions that are needed tomorrow. The main objective has been to develop new technologies and system concepts for buildings. Concepts that are highly flexible and respect the ambitions of the architect and technologies that will facilitate a more effective building process and address relevant key issues in building physics and building construction for cost reduction and a sustainable performance. Aside from the actual production cost it is also important to consider the lifecycle cost of the building. The production cost represents only a fraction of the total lifecycle cost of a building.</p><p>A background research has been made to understand the building process and its problems, this information served for the formulation of a building concept. The work has been interdisciplinary and has not been limited to only one single point of view. Because of the nature of the method the work has resulted in new construction techniques. The initial idea of the prefabricated high-rise building has during the course of this work developed to a complete building concept. The Symphony Concept as it is called is about industrial prefabricated buildings that are assembled on site and is based on the idea of large and flat building elements with a very high degree of prefabrication. To evaluate the concept technology detailed researches have been made in different fields. The detailed researches made in this thesis regards the strength of sheet metal studs embedded in stiff insulation blocks, hazards connected with plastering on light weight constructions and fire protection of light weight constructions. The experiences from these researches are then applied in the building concept. Theory was put to practice with the construction of an experimental building called the Research Tower. The purpose of this pilot-project was primary to evaluate the construction technology and secondary to evaluate the properties of the building concept.</p><p>To be able to find methods for production of sustainable, cost-effective and attractive high-rise buildings it is necessary to have a holistic view. A holistic concept that takes into consideration the whole building process will yield time- and cost-efficient production while it will also make it possible to achieve better quality. The detail researches shows that embedding of the sheet metal profiles in the rigid insulation blocks will increase the buckling load of the stud and that the thickness of the plastering layer and the material properties of its substrate will affect the strains in the plastering layer and the moisture stored in it. Regarding the fire protection it could be stated that the Symphony outer wall construction protected with a double layer of gypsum board can maintain segregation of the fire up to 60 min as long as the gypsum boards do not crumble. In the production of the pilot projected it could be stated that the fact that the whole building was designed by one homogenous team with information about all details, made it possible to foresee many problems. The production of elements even in the temporary experimental production facility proved to be fast and economic, even with untrained labour force and the elements could be prefabricated to a very high level with facades that are plastered before assembly.</p>

<p>One of the major degradation problems in concrete structures is chloride initiated reinforcement corrosion resulting in cracked, spalled and delaminated concrete. Thesedamages are repaired for large amounts of money and because of high repair costs it is important to perform durable repairs.</p><p>This thesis work has included interviews, laboratory and field studies in the area of concrete repairs. The interviews were held mainly with bridge engineers at the Swedish Road Administration and Banverket (the Swedish Railway Administration). The questions asked tothese people were about their experience in the field of concrete repairs. The objective withthe interview study was to collect knowledge and experience about concrete repair at these two governmental authorities.</p><p>The main objective of the laboratory study was to investigate chloride transport in the transition zone between a chloride contaminated substrate concrete and an initially chloride free repair concrete by establishing chloride profiles. The second objective was to detect any reinforcement corrosion in relation to the transition zone. The reinforced laboratory specimens with premixed chlorides (1 or 4 wt % per cement) in the substrate concrete have been exposed during 13 years either outdoors or in a climate chamber with relative humidity of 80 %. The main results show that reinforcement corrosion occurred in and near the transition zone in local active areas with passive areas between, macrocell corrosion, and that the chlorides are transported from the contaminated substrate concrete into the repair concrete.</p><p>Three different repaired concrete structures, one road bridge, one pedestrian bridge and one parking structure, were investigated in the field study. All three structures are treated with deicing agents in the winter time. The objective with the field study was to investigate if the same phenomenon can be observed as in the laboratory study. The main conclusions, from the investigation on drilled cores from each structure, are that chlorides in contaminated substrate concrete can be transported into a repair concrete and reinforcement corrosion may occur in the transition zone between the two different materials. The results are in accordance with the results in the laboratory study. It was also seen that a repair concrete with relative low w/cratio may reduce the ingress of external chlorides.</p><p>Finally, the results in this thesis indicate that there is a risk for reinforcement corrosion in the vicinity of the transition zone between repair concrete and a substrate concrete which must be considered in concrete repair work. For example the chloride content around a repair must not exceed a certain level when a repair is performed. The chloride transport into the repair concrete can be useful to transport chlorides and reduce the content of chlorides in the substrate concrete. The advantages with this are that the amount of removed contaminated substrate concrete can be minimized and the risk for corrosion in the substrate concrete is lower. If the repair concrete is reinforced with conventional black steel there may on the other hand be a risk for corrosion in the repair concrete instead if high levels of chlorides are transported. Also external exposure of chlorides must be considered for the risk of corrosion in the repair material.</p><p>Further research is needed about when different corrosion mechanisms and chloride diffusion mechanisms occur in reinforced concrete repairs. The experience from the used analyzing methods in the laboratory investigations are possible to use in coming research projects in the field of concrete repair. The next step after this thesis work should be in order to increase the understanding of the repaired concrete system including the important compatibility issues, the author believes that the most fruitful way consists of further laboratory investigations, field studies and optimisation of the repair material.</p>

<p><b>Bleeding of cement based grout</b></p><p>Bleeding of cement based grout is a complex problem. How it occurs and which basic mechanism causes and influences bleeding have been questions for discussion. Therefore the aim of the thesis is to illustrate what really happens with grout during bleeding and which factors influence it. In this way relevant measuring methods can be developed as well as the knowledge regarding how to interpret measuring results to joints in rock.</p><p>The bleeding tests show that there are two basic mechanisms which cause bleeding. They are sedimentation and consolidation. It also means that the bleeding process is influenced by sample height. It was found that bleeding of coarse cement (ANL) was mainly a result of sedimentation of the grout. Experiment with fine cement (INJ30; d₉₅<30 µm) shows that the consolidation part of bleeding was larger.</p><p>The study shows that the bleeding process for a low sample height (10 mm) occurs fast. Extrapolation of experiment results and theoretical analysis shows that bleeding in a joint happens very fast and takes place during grouting itself. It means that results measured by standard methods can not be applied straight off for joints in rock.</p><p>Theoretically bleeding occurs relatively slowly in vertical or inclined joints due to increased height. Bleeding will be resisted by arching and hardening. Reasonably, very little bleeding will take place.</p><p><b>Filtration of cement based grout</b></p><p>How far grout penetrates into a joint is not just influenced by the rheology of the grout like viscosity and shear strength, but also by the tendency of the grout to get stuck which means to build a plug. Factors which influence the building of a plug are properties of the grout, geometry of the joints including rawness of the joints and proceeding of the grouting.</p><p>Today there are many different ways to measure filtration of a grout or the building of a plug. The different methods give different results and thus the importance of the influence of different factors is interpreted differently.</p><p>The experiments in this thesis are done in a 100 mm long, 50 mm wide aperture with 1 mm width. Thereafter the width of the aperture decreases to 0.02 – 0.3 mm over a 10 mm long distance.</p><p>The results of the experiments in this thesis, measured by own method, show that the best penetration ability with respect to filtration has a grout based on relatively fine-graded cement (INJ30; d₉₅<30 µm).The penetrability of the grout based on more graded cement decreases because of flocculation. In total tens measurements have been done. The measurements confirm others’ experiments which show that the concentration of fine-graded particles (< 4 µm) has a large influence on flocculation and with that the building of larger grains.</p><p>It is important to remind that the mixing of grout has been done by a laboratory mixer, which is not a mixer of colloidal type. This issue has to be further tested.</p><p>The research shows that filtration of grout is also influenced by grain size of cement and the water cement ratio. The filtration test carried out by own measuring method with varying pressure showed a better penetrability for a larger pressure. It influenced both arching and erosion of the accumulated particles.</p>

<p>Out of the total 540 000 km Swedish road network, approximately 400 000 km represents gravel roads. According to data from the Swedish Road Administration (SRA), the length of the public road network administered by the government amounts to 100,000 km. About 20% of this network comprises of gravel roads. The traffic volume on these gravel roads is very small, i.e. less than 125 AADT but these roads can be of great regional importance and are often a direct prerequisite for the transportation of forest products; the largest export product of the country. These roads are also essential for the survival of sparsely populated regions.</p><p>An increased amount of particulate matter in the air could give rise to reduced traffic safety, clogging of watercourses, air pollution, damage to agriculture, and have negative health implications.</p><p>If the fines in the gravel wearing course disappear, this is likely to lead to the loss of other larger sieve fractions of the aggregate. The deficiency of gravel course material implicates more frequent maintenance, as well as increase demands of aggregate supplement, both of which will result in higher costs. Dust suppressants not only, and efficiently, reduce the amount of dust raised by traffic induced wear, but they also reduce overall gravel road maintenance costs (Kirchner, 1988). On the other hand, dust suppressants, especially chlorides, may also negatively affect the environment, and for example cause corrosion to cars or dehydration to road side vegetation.</p><p>Approximately 5%, or 370 MSEK, of the total annual SRA maintenance budget is assigned to these roads. However, there is also a significant expense associated with dust control. Dust binding is expensive, as it amounts to 30% of the total expenses for the maintenance of the gravel roads during the period when the ground is free from snow (Bergström and Grebacken, 1995). This expense is, of course, affected by the type of dust suppressant, the concentration of used dust suppressant, and the number of treatments. However, at present there is a real lack of knowledge concerning the efficiency, durability, life cycle cost, and impact on the environment from the different dust suppressants utilized.</p><p><b>Objective and Delimitations</b></p><p>The objective of this study is to evaluate dust suppressants and gravel wearing courses regarding dust control efficiency, longevity, leaching and penetration of dust suppressants, moisture retaining properties, and optimal aggregate size distribution. In addition, developing and evaluating adequate methods for analysing these properties are also within the purpose of the study. The methodology used includes literature reviews as well as laboratory and field investigations. The findings are expected to yield reduced life cycle costs for gravel roads and environmental benefits from reduced dust formation as well as reduce the exposure of chemicals to nature. The study is valid for the Nordic climate, design practices, gravel material, and maintenance tradition.</p><p>Still there are reasons to believe that the results are also valid for gravel roads in other countries when using these kinds of dust suppressants.</p><p><b>Literature study</b></p><p>Certain dust suppressants depend on absorbing moisture from the air to reduce dust. Others rely on adding cohesion to the aggregate material for the same purpose. Hygroscopic salts, such as calcium and magnesium chloride, use the former principle while lignosulphonates and bitumen emulsion primarily use the latter. Regardless of the mode of action, the result of dust suppressant treatment is temporary and therefore, at least, renewed treatment annually (U.S. Department of Transportation, 2001).</p><p>Calcium chloride is by tradition the most common used dust suppressant in Sweden, followed by, in turn, magnesium chloride, lignosulphonate, and bitumen emulsion. Treatment with either chloride or lignosulphonate has a duration of about six months, according to literature (Lohnes and Coree, 2002). Chloride is stated to be most effective with surface wearing courses with moderate content of fines whereas lignosulphonate works best with aggregates that have high content of fines (Gillies et al, 1999). Finally, bitumen emulsion (BE) is said to have a duration of approximately twelve months (Gillies et al, 1999) and to be most effective in combination with coarser grains, thus having less grain surface area to cover (Bergström and Grebacken, 1995).</p><p>A major disadvantage with chlorides is that they are water soluble and tend to migrate downwards through the roadway. They are easily washed away by rain, which may imply that more than one treatment per year is required (Foley et al, 1996). Another problem regarding chlorides is that they are corrosive to most metals.</p><p>Calcium chloride and magnesium chloride have several common qualities and work as dust suppressants on the same basis. However, up to 20 wt-% more magnesium chloride is needed to achieve the corresponding dust controlling effect as with calcium chloride (Reyier, 1972).</p><p>Lignosulphonate is also called sulfite lye or lignin. Lignin is a major constituent of wood, i.e. 33-40% of dry weight (McDougall, 1986). It works as nature’s own adhesive and binds the wood fibres together. Lignosulphonate is obtained as a waste product during the boiling of wood for paper pulp production.</p><p>There are several different types of lignosulphonates, i.e. calcium-, sodium-, and ammonium lignosulphonate, where calcium lignosulphonate represents the most commonly used (Roads and Transportation Association of Canada, 1987). Experiences from Canada indicate that sodium and calcium lignosulphonates are equally effective (Chichak, 1991).</p><p>Lignosulphonate creates a hard surface crust on the road but the product is highly water soluble and therefore tends to leach from the road during heavy rainfall, which implies that this dust suppressant is much more effective in a dry than in a wet environment (Jones, 1999).</p><p>It seems as though the grain size distribution is especially important when dust suppressing with lignosulphonate while BE and chlorides are not as sensitive to variations in grain sizes. The adherent effect of lignosulphonate is significantly lowered if the content of fines is too low. Clay also prevents the lignosulphonate from leaching during rainfall (Svensson, 1997). In addition, if the lignosulphonates, as well as the chlorides, are mixed into the wearing course aggregate, they are noted to show greater longevity (Hoover, 1981).</p><p>The amount of emitted dust from gravel roads is considered to be a function of several different factors. These include: number of vehicles, vehicle weight, vehicle speed, number of wheels per vehicle, grain size distribution of the wearing course material, restraint of the surface fines (compaction, cohesiveness/bonding, and durability), surface moisture (humidity, amount of precipitation, and amount of evaporation), and topography (Addo and Sanders; 1995; Bolander and Yamada, 1999). Findings in literature indicate that all dust control treatments may reduce dusting of up to 80% when compared to untreated, reference roads (Hoover, 1973). Failures are usually ascribed to the loss of dust suppressant during rainfall. However climatic conditions, wearing course aggregate, traffic, and dust suppressant concentration used will all affect the effectiveness and life-time of the treatment.</p><p>Examinations of road dust may be divided into two categories: laboratory screening tests, which are used to determine if a dust suppressant actually works for preset, controlled conditions or application rate needed; and field tests, which give realistic test conditions and often include static dust collectors or mobile, measuring devices.</p><p><b>Dust formation on gravel road test sections</b></p><p>With the objective of comparing the effectiveness of different dust suppressants and of studying the influence of altered concentrations as well as new combinations of dust suppressants, a field experiment was established on four different geographic locations in Sweden: Umeå, Rättvik, Hagfors, and Halmstad. At each location a stretch of road was further divided into a number of 1000m test sections marked by signs at both ends. Different dust suppressants were then applied to these 1000m sections. Magnesium chloride solution, calcium chloride solution, magnesium chloride flakes, calcium chloride flakes, lignosulphonate, and a solution of starch were tested on all test locations. In addition, bitumen emulsion and biomass were tested in Hagfors and rape oil in Halmstad. Mesa, a material that is used for increasing the amount of fines in the aggregate, was tested in combination with calcium chloride solution, magnesium chloride solution, and lignosulphonate, respectively.</p><p>For assessing the amount of dust emitted from the different test sections, TSI DustTrak Aerosol Monitor was used in combination with visual assessments. The DustTrak apparatus uses a 90º light scattering laser diode sensor for real-time determination of aerosol mass concentrations in the range of 0.001-100 mg m-3. The amount of light scattering is proportional to the mass concentration of the aerosol for particles ranging in size from 0.1 to 10 μm (Hitchins, 2000; Wu, 2002; Veranth et al, 2003).</p><p>For the DustTrak measurements, an estate car was used. The vehicle was driven at a constant speed of 40 km/h over the entire road length and so passing all test sections. The driving pattern was to the greatest extent possible restricted to the existing wheel tracks. A PDA connected to a GPS, was programmed to register time, current test section, and vehicle velocity. These data were then combined with the obtained DustTrak data.</p><p>The results obtained through this objective method were compared to results obtained from visual inspections made in accordance with the subjective assessment directives (Vägverket, 2005). This was done with the intention of evaluating the method for recording dust emissions and hence look into the possibility of developing an unbiased method to replace the existing subjective method for assessing dust emissions on a gravel road. Compared results expose a fairly good correlation.</p><p>The difference in aerosol particle mass concentration between a dust suppressed and an unbound, natural gravel road is remarkably large. Dust suppressants creating a hard surface crust, such as lignosulphonate, but also bitumen emulsion, performed acceptably well in the beginning stages but ruptured and became ineffective after a while. The lignosulphonate was one of the least effective of the products tested. However in Umeå, it was one of the most effective, if not the most effective. It was concluded, through an analysis by means of a scanning electron microscope (SEM) that the well performing lignosulphonate product used in Umeå was sodium lignosulphonate while the surface rupturing product used at all other test locations was calcium lignosulphonate. The sodium lignosulphonate had higher relative levels of sulphur, while the calcium lignosulphonate had higher relative levels of carbon and oxygen. This, together with the difference in calcium and sodium composition, could explain the differences in performance. Sections treated with starch also raised much dust as did the biomass product, probably due to fast leaching and degradation. In fact, the latter section rapidly deteriorated to such bad condition that it had to be excluded from the test and dust suppressed by conventional means. The rape oil product applied in Halmstad, formed a hard crust which was also subjected to surface rupture but which lasted almost throughout the whole summer and during this time performed very well. However the utilized concentration of the rape oil was rather high and this product is still expensive.</p><p>Solid calcium chloride is 10 to 40% or, on average from all observations, 19% more effective than magnesium chloride. This agrees well with an earlier estimation, indicating that calcium chloride is 18% more effective than magnesium chloride (Reyier, 1973). It is shown from all of the test locations that a solution of either magnesium chloride or calcium chloride is the most effective choice for dust abatement. This finding is thought to be due to a more homogenous distribution of chlorides, in combination with better penetration, for solutions than for flakes. Even though a somewhat higher chloride concentration can be obtained from purchasing a ready-to-use solution, it is probably more cost and energy effective to prepare the solution from a solid product on location, if possible out of practical reasons.</p><p>The addition of mesa, and hence fines, to the aggregate appeared to have no positive effect on the efficiency of chlorides. However the results are hard to interpret due to different initial concentrations, as the salt concentration was reduced on sections where mesa was used.</p><p><b>Laboratory methods for determination of dust suppressant residual content over time of the road test sections</b></p><p>The goal was to study how concentrations change with time. In order to do this we had to develop new methods to quantify residual chlorides and lignosulphonates.</p><p>Samples were taken of the wearing course gravel from a square measuring 150 x 150 x total thickness (usually on the order of 40 mm). The samples were taken from the same general area after different laps of time. In general the sampling site was the mid point of the section and in the right wheel track. The samples were given the same number as the section.</p><p>Chloride and lignosulphonate treated gravel road sections were analysed for decreasing residual content over time. Eight sections in total were analysed: 1.0 kg/m and 0.7 kg/m calcium chloride, 1.0 kg/m and 1.3 kg/m magnesium chloride, calcium chloride solution, magnesium chloride solution, lignosulphonate, and lignosulphonate in combination with mesa.</p><p>Deionised water measuring 50 mL, was added to 50 g of gravel wearing course material in a glass beaker. The dust suppressant residues were dissolved by submerging the beaker containing gravel into an ultrasound bath for 10 minutes. This solution was then filtered into a clean glass beaker. The chloride containing filtrate was put into Eppendorph tubes and centrifuged for further separation of fine mineral particles. Filtrate containing lignosulphonate was instead filtered once more with a PTFE-membrane, with the purpose of minimizing background disturbances from fine mineral particles.</p><p>Chloride content was analyzed calorimetrically using the Mercury (II) Thiocyanate Method. In this method, an orange-coloured complex of ferric thiocyanate is formed when chloride ions disperse the mercury ions of mercuric thiocyanate in the presence of excess ferric nitrate. The resulting colour was measured on an ion specific photometer.</p><p>Results indicate that the chloride content of gravel wearing courses treated with chloride containing dust suppressants dicreases rather fast during the summer months. It can be concluded that there is not enough chloride left in the road surface after the summer, such that yearly renewed application would be unnecessary. It is apparent that re-blading of the road impacts the chloride concentration on different spot locations within the individual test sections and re-blading was done frequently on some test sections and that will make the results more difficult to interpret and draw conclusions from.</p><p>It is also obvious that the chloride concentration in the gravel wearing course most often increases during some weeks after the dust control treatment. The reason for this is not yet understood or sufficiently investigated.</p><p>A theory to the increasing chloride concentration during some weeks after the point of application is that during wet weather, as initially in the season, the chlorides follows the water runoff streams downwards and hence cannot be collected when taking samples in the gravel wearing course. During periods of dry weather, the surface moisture of the road evaporates causing moisture from deeper below to travel up towards the road surface by means of capillary rise. This causes the chloride concentration to increase within the gravel wearing course since the upwards travelling water also carries the dissolved chlorides. This is supported by findings that the chloride content in the gravel wearing courses increases during a time period of less precipitation after the application activity and then decreases during periods of more heavy precipitation. However, this should be easy to investigate further by continuously collecting samples from different levels of depth within the road pavement.</p><p>The chloride residual content over time for the section treated with 1.3 kg/m solid magnesium chloride is approximately equivalent to the section treated with 1.0 kg/m solid calcium chloride and the residual content over time for the section treated with 1.0 kg/m solid magnesium chloride is approximately equivalent to the section treated with 0.7 kg/m solid calcium chloride. These observations are significant at the 5% level for at least two of the occasions of sample collection in Rättvik during 2006 and coincides with a stated theory that 30 wt-% more magnesium chloride than calcium chloride is required to achieve equal chloride concentration. The results also indicate that sections treated with chloride solutions have the lowest concentration of residuals. This might imply that a homogenous horizontal and vertical distribution of chlorides within the wearing course is equally important as a high concentration of chlorides.</p><p>A uv/vis-spectrophotometer was used to estimate the content of lignosulphonate in samples taken from wearing courses from the different field trial sections treated with the product. A calibration of the method indicated that the lignosulphonate samples may be quantified if measured at the wavelength 280 nm, corresponding to the wavelength at which lignin absorbs light. Samples containing high concentrations of lignosulphonate need to be diluted before measurement.</p><p>Also the lignosulphonate seems to rapidly decreasing with time during the summer months, probably even faster than the chlorides. Contrary to sections treated with chlorides, where residual content actually increased during a time interval after the point of dust suppressant application, the residual content of lignosulphonate started to rapidly decrease directly following the occasion of application.</p><p><b>Horizontal diffusion of particulate matter from gravel roads</b></p><p>European Council Directive 1999/30/EC states limit values for sulphur dioxide, nitrogen dioxide, lead, and particulate matter in ambient air. This directive, valid from the 1st of January 2005, states that the average daily concentration of particles smaller than 10 μm, PM10, should not exceed 50 μg/m3 for more than 30 times a calendar year and that the total average yearly concentration should not exceed 40 μg/m3. From the 1st of January 2010, the corresponding values are 50 μg/m3 per 24 hours not to be exceeded more than seven times a calendar year and a maximum of 20 μg/m3 for the average yearly concentration.</p><p>The correlation between the mass concentrations of airborne PM10 particles and distance from the road has been studied by placing DustTrak equipments at different distances from the road edge. The equipments were placed on an open field in a downwind location from a gravel road.</p><p>There seems to be a linear correlation between mean mass concentration of PM10 and dust decay with the distance from road edge. If the regression is extrapolated, it indicates that particles travel no further than 45m downwind from the road edge in prevailing wind velocities between 0 and 7 m/s. It hardly seems possible that larger particles than these would travel further.</p><p>The highest mean PM10 concentration obtained, slightly above 0.5 mg/m3, at a distance of 5 m from the road edge corresponds to a mass concentration ten times greater than the permitted mean PM10 concentration during 24 hours, according to the directive. Since this mean particle concentration was obtained during one hour, with a traffic density of, or as much as, one car per minute, it hardly seems likely that the European Council directive is infringed on locations beside the road.</p><p><b>Laboratory study of dust suppressant leaching</b></p><p>Experiments for studying dust suppressant leaching from granular material of different composition have also been performed in the laboratory environment. Plastic measuring cylinders with small holes drilled in the bottom were used for holding different material fractions. Fractions 0-0.5 mm, 0-2 mm, 0-4 mm, 0-8 mm, 0-16 mm, 2-16 mm, and 0-16 mm containing an addition of 10 wt-% clay were put into the cylinders. Unfortunately, the test material used was somewhat deficient in fines, i.e. containing about 4 wt-% passing the 0.075 mm (mesh no. 200) sieve. Compacted samples were then subjected to dust suppressant solutions and water leaching.</p><p>Analysis of the variance of means from chloride leaching shows significant differences to the 5% level among means regarding different aggregate fractions, but shows no significant difference among means between 0-16 mm material with an addition of clay and 0-16 mm material without addition of clay. Material fraction 0-2 mm is the most efficient in retaining chlorides, and chloride leaching increases with increased material fraction sizes beyond this fraction.</p><p>The 43 wt-% lignosulphonate solution, as used in Halmstad, was used to study lignosulphonate leaching. The results indicate that the lignosulphonate is at least, equally prone to leaching as are the chlorides. In similarity to chloride leaching, the coarser the granular material fraction is the higher the concentration of lignosulphonate within the leachate. It is also apparent that the addition of 10 wt-% clay into the 0-16 mm granular material fraction, initially containing about 4 wt-% fines, clearly decreases the rate of lignosulphonate leaching. However it was seen during these experiments that the water, added for rain simulation, stayed longer on the surface before draining into the material. Therefore, the addition of clay may cause excessive water retention and hence possibly a wet, smeary, and slippery road surface.</p><p><b>Influence of grain size distribution and chloride concentration on the drying process</b></p><p>Water is often referred to as nature’s own binding agent. Therefore an aggregate with good moisture retaining properties is a good investment. The mode of action regarding salts are their hygroscopic, i.e. moisture retaining, properties. In addition, the grain size distribution is also thought to influence the moisture content of a gravel wearing course, with finer material fractions retaining moisture more efficiently. Therefore the influence of grain size distribution as well as chloride type and concentration on the drying process were assessed in the laboratory.</p><p>The drying rate of the aggregate was defined as the water loss (gram) within a unit of time (hour). Since the experiment was set up to provide for relative readings, and all samples had the same surface area, the surface area was not taken into consideration when calculating the drying rate. The experiment was performed on material fractions 0-0.5 mm, 0-2 mm, 0-4 mm, 0-8 mm, 0-16 mm and 2-16 mm. Drying was first carried out without the addition of salt and subsequently with a 30 g addition of calcium chloride and magnesium chloride, respectively.</p><p>During the concentration interval which is reasonable out of economic reasons, the water retaining capacity increases with increasing chloride concentration for both calcium chloride and magnesium chloride treated aggregates.</p><p><b>Development of a laboratory method for studies of dust formation</b></p><p>Preliminary experiments to develop a fast, relatively simple, and reliable laboratory method for the examination of dust suppressant effectiveness have been carried out. This method should be able to evaluate the influence on dust control efficiency of; concentration and type of dust suppressant, grain size distribution of granular material, precipitation, temperature, and traffic intensity.</p><p>A high pressure air device was constructed with the purpose to simulate vehicle wakes which raise dust into the air. A Proctor compaction device was incorporated to achieve compaction, thus forcing the fines up towards the surface; and crushing, thus increasing the content of fines, of the aggregate material. The compaction subjected the grain particles to wear and therefore clearly accomplished a larger content of fines. Also observed was that the compaction forced the fines up towards the surface whilst the opposite was observed for the uncompacted control. The results clearly state that the compaction also caused a more well-bound fines fraction, giving rise to less dust than the uncompacted control. Further, even the smallest addition of salt, corresponding to 3.75 g CaCl2 per 2700 g granular material, eliminated dust generation. . This amount is equivalent to about 60 g/ m2, which can be compared with the typically applied amount of about 200 g/ m2 when dust suppressing with MgCl2 on the gravel road.</p><p>Wearing course material from eight of the test sections included in the field trial in Rättvik was collected and put into laboratory containers for comparison between the equipment used in the field and the developed laboratory device. The biggest advantage with the laboratory device, in comparison to the DustTrak equipment used in the field trials, is that this apparatus, besides allowing for relatively simple laboratory tests, collects emitted dust fraction and thus renders possible complementary analyses of this fraction. The results indicate that there is no statistical evidence at the 5% level for any difference among the sample means of the different road sections. In fact, it is possible that there, are no differences among the sample means, since the samples were collected late in the season when re-blading of the whole road had been made and the concentration of dust suppressant thus most likely was low. In resemblance to the result from the field evaluations, large standard deviations were obtained for comparisons between different samples on the same section. This may indicate that dust emission varies greatly in different spot locations on the road or that the method does not offer very reproducible results. This must be the subject for further studies</p><p><b>The most important findings of this project study:</b></p><p>• Solid calcium chloride is on average 19% more effective at holding the dust than the equivalent amount of solid magnesium chloride.</p><p>• A solution of either magnesium chloride or calcium chloride is the most efficient dust suppressant.</p><p>• Sodium lignosulphonate, with a relatively larger content of sulphur and sodium, is much more effective than calcium lignosulphonate, containing a relatively larger amount of calcium, oxygen, and carbon, for dust suppressing purposes.</p><p>• An objective method for quantifying the amount of dust on gravel roads has been evaluated. The method gives the opportunity to distinguish between sections treated with different dust suppressants. The method has been compared with visual inspections and shows a relatively good correlation. It gives substantial and reliable results. However the method has only been calibrated for a constant vehicle speed of 40 km/h.</p><p>• Statistical analyses, from visual inspections of the road condition, at the 5 % level conclude that the amount of dust raised by traffic can be used as a predictor for development of both evenness and loose gravel on the road surface.</p><p>• Methods for residual content quantification of chlorides as well as lignosulphonate have been developed and seem to work satisfactory.</p><p>• Any residual content regarding both chlorides and lignosulphonate is in principle non-existent in the surface wearing courses after the summer season. Calcium lignosulphonate is especially fast leaching which probably explains why roads which are dust suppressed with this product gives of much dust already in the beginning of the summer.</p><p>• After the application occasion, the chloride residual content in the gravel wearing course increase during a period of less precipitation and then starts to decrease rapidly during periods of more heavy precipitation. This is, however, more pronounced for solid salt than for salt solutions.</p><p>• The particle emission diffuses no further than 45 m down wind from the gravel road in prevailing wind velocities of between 0 and 7 m/s.</p><p>• Even regarding locations very close to the gravel road, there is a very small risk of exceeding the maximum allowed daily average concentration of PM10 stated by the European Council directive.</p><p>• Lignosulphonate is remarkably favoured by a larger content of fines. Much less lignosulphonate is leached from the granular material if clay or mesa is added to obtain a total content of fines of about 15 wt-%. The corresponding effect, from increasing the content of fines, was not seen in neither the field nor the laboratory regarding the leaching propensity of salt.</p><p>• The moisture retaining, i.e. hygroscopic, property of magnesium- and calcium chloride increases with increasing concentrations until a peak concentration, where further increases in concentration yield no efficiency gains. However at the concentration interval which is reasonable out of economical reasons, both calcium- and magnesium chloride treated aggregates benefit from increasing the chloride concentration.</p><p>• A finer aggregate fraction does not hold water more effectively, in fact the opposite is true, but it can absorb more water and therefore is more effective from a moisture retaining perspective.</p><p>• A laboratory method, incorporating a handheld dust generating and collecting device, for pre-assessing the efficiency of dust suppressants has been developed and pre-evaluated. Preliminary results suggest that the amount of accessible dust in different local spots is highly variable. This suggests that it is difficult to obtain a good reproducibility with this method. The highly dust variable local spots are also an apparent problem on the road. The developed objective method collecting PM10 solves this problem by recording numerous sample points.</p><p><b>Future studies</b></p><p>Some future studies within this project are already planned. For example, the field study will go on during one more season. The f

<p>In the design of structures to resist the effects of air blast loading or other severe dynamic loads it is vital to have large energy absorbing capabilities, and structural elements with large plastic deformation capacities are therefore desirable. Structures need to be designed for ductile response in order to prevent partial or total collapse due to locally failed elements. The research in this thesis considers experimental and theoretical studies on concrete beams of varying concrete strength. The nominal concrete compressive strength varied between 30 MPa and 200 MPa. A total of 89 beams were tested of which 49 beams were reinforced with varying amounts of tensile reinforcement. These beams were also reinforced with stirrups and steel fibres were added to a few beams. The remaining 40 beams were only reinforced with steel fibres with a fibre content of 1.0 percent by volume. Two different fibre lengths having constant length-to-diameter ratio were employed. The tests consisted of both static and air blast tests on simply supported beams. The blast tests were performed within a shock tube with a detonating explosive charge. All experimental research focused on deflection events, failure modes and loads transferred to the supports. The dynamic analyses involve single-degree-of-freedom (SDOF) modelling of the beam response and the use of iso-damage curves. Also, the dynamic support reactions were calculated and compared with test results.</p><p>For beams with tensile reinforcement, the failure mode of some beam types was observed to change from a flexural failure in the static tests to a flexural shear failure in the dynamic tests. Beams with a high ratio of reinforcement and not containing steel fibres failed in shear, whereas beams with a lower ratio of reinforcement failed in flexure. The introduction of steel fibres prevented shear cracks to develop, thus increasing the shear strength of the beams. The presence of steel fibres also increased the ductility and the residual load capacity of the beams. Beams subjected to air blast loading obtained an increased load capacity when compared to the corresponding beams subjected to static loading. The SDOF analyses showed good agreement with the experimental results regardless of concrete strength and reinforcement amount. The results of using iso-damage curves indicate conservative results with larger load capacities of the beams than expected. The theoretical evaluations of the dynamic reactions were in agreement with the measured average reactions, both in amplitudes and in general shape.</p><p>The experimental results with steel fibre reinforced concrete beams indicate that the dynamic strength was higher than the corresponding static strength and that the toughness was reduced when increasing the compressive strength. Beams of normal strength concrete failed by fibre pull-out while a few beams of high strength concrete partly failed by fibre ruptures. It may be favourable to use shorter fibres with smaller aspect ratios in structural elements of high strength concrete and subjected to large dynamic loads.</p><p>Further research should involve studies on the size effect, on different boundary conditions, on different types of structural elements and on the combination of blast and fragment loads. The theoretical work should involve analyses both with the use of SDOF modelling and finite element analysis.</p>

<p>The use of Phase Change Material, PCM, to change the thermal inertia of lightweight buildings is investigated in the CRAFT project C-TIDE. It is a joint project with Italian and Swedish partners, representing both industry and research. PCMs are materials where the phase change enthalpy can be used for thermal storage. The Swedish application is a night ventilation system where cold night air is used to solidify the PCM. The PCM is melted in the day with warm indoor air and thereby the indoor air is cooled. The system is intended for light weight buildings with an overproduction of heat during daytime. In the thesis, the results of experiments and numerical simulations of the application are presented. The theoretical background in order design the heat exchanger and applying the installation in thermal simulation software is presented. An extensive program is set up, in order to develop test methods and carry tests to evaluate the performance over time of the PCM. Testing procedures are set up according to ISO standards concerning service life testing. The tests are focused on the change over time of the Thermal Storage Capacity (TSC) in different temperature spans. Measurements are carried out on large samples with a water bath calorimeter. The service life estimation of a material is based on the performance of one or more critical properties over time. When the performances of these properties are below the performance requirements, the material has reached its service life. The critical properties of the PCM are evaluated by simulation of the application. The performance requirements of the material are set up according to general requirements of PCM and requirements according to building legislation. The critical properties of a PCM are the transition temperature, the melting temperature range and the TSC in the operative temperature interval. The critical property of the application is its energy efficiency.</p><p>The results of the study show that the night cooling system will lower the indoor air temperature during daytime. It also shows that the tested PCM does not have a clear phase change, but an increased specific heat in the operative temperature interval. Increasing the amount of material, used in the application, can compensate this. Finally, the tested PCM is thermally stable and the service life of the product is within the range of the design lives of the building services. It is essential to for all designers to know the performance over time of the properties of PCMs. Therefore it is desirable that standardized testing methods of PCM are established and standardized classification systems of PCMs are developed.</p>