Vid gruvbrytning genereras bland annat ett finmalet gråbergsavfall, anrikningssand. Den vanligaste deponeringsmetoden för anrikningssand är att den tillsammans med vatten pumpas eller leds till en gruvdamm. Där deponeras anrikningssanden genom sedimentation. Trots att det är den vanligaste deponeringsmetoden är den behäftad med svagheter. Det uppdämda vattnet i gruvdammen kan ge upphov till incidenter och i olyckliga fall till allvarliga haverier. Ett sätt att minska riskerna och att öka stabiliteten, är att deponeringen sker under dränerade förhållanden. Detta kan åstadkommas med hjälp av sildammar. För att studera funktion och lämplig uppbyggnad av sildammar har ett anta fält- och laboratorieförsök genomförts. Grovkornigt gråbergsavfall, kallat sovringsgråberg, användes när sildammarna byggdes. Sildammarnas uppgift var att hindra flödet av anrikningssand genom filtrering och samtidigt tillåta dränering av inpumpat vatten. Syftet med denna licentiatuppsats har varit att hitta en lämplig design för sildammar. Efter en inledande litteraturstudie byggdes testanläggningar, både som rännförsök och i pilotskala. I testanläggningarna testades olika sildammar genom att dess filtrerande och dränerande förmåga undersöktes. Testerna föregicks av laboratorieförsök där sildammsmaterialens hydrauliska konduktivitet undersöktes. Testerna visar att vid valet av lämpligt material för sildammar, kan filterkriteria användas tillsammans med bedömningar av materialets hydrauliska konduktivitet. Finns inte lämpligt sovringsgråberg att tillgå, kan geotextiler användas som filter i en sildamm. Sildammarnas filtrerande förmåga beräknades som verkningsgrader, vilka låg mellan 34 - 100 % beroende på sildammarnas design. Sildammarnas dränerande förmåga beräknades i det deponerade materialet med hjälp av uppmätta och beräknade porvattentryck. Porvattentrycken sjönk mellan 60 - 100 % under testperioden. Testerna visar att det deponerade materialets egenskaper påverkas av den inpumpade mängden av vatten och anrikningssand samt av sildammarnas funktion. Där sildammens filtrerande förmåga var hög, tog det längre tid innan det deponerade materialet dränerades. Vidare påverkas sildammarnas funktion av det deponerade materialets egenskaper. Vid deponeringen skedde en partikelsegregering, då de tyngsta partiklarna sedimenterade närmast inloppsröret medan lättare partiklar transporterades längre innan de sedimenterade. Denna segregation påverkar sildammens dränerande funktion negativt. Sildammen kan inte filtrera enbart de finkornigaste partiklarna samtidigt som sildammen skall dränera det inpumpade vattnet. Ju mer omfattande partikelsegregationen är och ju bättre sildammen kan hindra de finkornigaste partiklarna, desto större kommer sättningarna i det sedimenterade materialet bli nära sildammen. Detta kan försvåra dränering av ytvattnet. Testerna genomfördes sommartid. Framtida undersökningar bör koncentreras på att anpassa metoden även för vinterförhållanden. Vidare bör materialprover tas för att få en bättre uppskattning av partikelsegregationen. Målet är att kunna beräkna deponins optimala storlek. Slutligen bör ytterligare fältförsök genomföras där anrikningssanden deponeras i våningar. Vid dessa försök bör det deponerade materialets dräneringsförmåga ytterligare utredas tillsammans med undersökningar av eventuella erosionsproblem i underliggande sildammar från dränerat vattnet. / Godkänd; 2005; 20061215 (haneit)

Three papers form the present thesis. In paper I a numerical model for calculation of surface temperatures on a highway is presented. The model takes all relevant factors into consideration, i.e. conduction, wind, short- and long wave radiation. Temperatures obtained by the model are compared with those measured in a highway pavement. A good correlation is obtained. The model is using the position of the sun as input data and is not considering noon time conditions all the day, as in many other models for surface temperature calculation. In paper II and III a simple numerical model for calculation of frost depth and frost heave in highways is presented. Calculation results are compared with data obtained from two different test sites. Comparison is also made to laboratory tests conducted by using a new laboratory-testing device, developed by the author. The equipment is described in paper III. It is further argued, that frost heave to great extent is caused by ice lenses formed by water from the pores in unfrozen soil and only to a minor extent by water taken from the ground water, which is normally assumed. Good correlation is found between calculated and observed frost penetration and frost heave, in both field and laboratory condition. Special attention is paid to the influence of heave rate and water intake rate. / Godkänd; 2000; 20070318 (ysko)

tabilization and solidification (S/S) technique have been the most frequently used method for dredgedsediment improvement in Sweden and worldwide. As dredging activities are essential for safe navigationof ships and vessels that may processes harmful substances or organic pollutants to causecontamination of the surrounding environment. Stabilization/solidification technology has beenidentified as the most beneficial handling strategy for contaminated dredged sediments and treatedstabilized materials can be used in civil engineering applications (e.g. backfill or embankment). This (S/S)technique is the easiest way of improving high water content dredged sediments using different types ofbinders. During the stabilization process, dredged sediments are mixed with commonly used binders,such as Portland cement, fly ash and ground granulated blast furnace slag (Merit 5000). Nowadays,supplementary cementitous materials such as (fly ash and blast furnace slag) are being used increasinglyconsidering long term strength development of stabilized dredged materials instead of using morecement. Generally, cement hydration is a complex chemical-reactions. By addition of supplementarycementitious materials, it becomes more complex because of cement hydration and pozzolanicreactions. The overall objective of this thesis work is to improve the understanding of compressibilityand strength behavior of stabilized dredged materials. To achieve these objectives, a series ofunconfined compressive strength tests and consolidation tests were performed on stabilized dredgedmaterials (SDM) with different types and mixing ratios of binders. These lab tests have been focused onthe compressibility and strength properties of stabilized materials. The UCS test determines the amountof binders and curing time needed to achieve the required shear strength of SDM. The outcomes of thisthesis work show that the stabilized dredged sediments constitute of binder mixing ratio (Cement:Flyash:Merit 5000 as a proportion of 10:10:5) which is 25% of the total fresh dredged sediments can’tsustain any superstructure or surcharge load but it can only be used as backfill materials on site.Whereas, stabilized dredged material with binder mixing ratio (Cement:Fly ash:Merit 5000 as aproportion of 20:20:10) which is 50% of the total fresh dredged Sediment becomes stiff after 28 dayscuring and becomes very stiff after 91 days curing. It becomes obvious that the unconfined compressivestrength of SDM increases with higher amount of binders and longer curing time. The pozzolanicreaction continues after 28 days curing period. The presence of supplementary cementitous materials(fly ash, blast furnace slag and merit 5000) can improve the ductility of stabilized dredged materials(SDM) in the post-peak strength degradation zone without changing the unconfined compressivestrength. It is also obvious from the test results that the UCS values of stabilized dredged materialsincrease with decreasing moisture content/increasing bulk density. The consolidation properties of SDMare greatly influenced by the binder mixing ratio, curing time and preloading weight. Due to preloadingweight, the deformation in stabilized dredge sediments is irreversible because of cementation andpozzolanic effects. Considering both curing time and binder ratio, compression index (Cc) and swellingindex (Cs) values for SDM with binder ratio (20:20:10) have been lowered approximately by 75% and67%, respectively than SDM with binder ratio (10:10:5). After 91 days curing of SDM with binder ratio(20:20:10), the maximum value of tangent modulus is estimated about 9624 kPa which indicates thatthe superstructure can be erected on stabilized dredged materials. It is also concluded that physicochemicalvariables control the consolidation behavior of stabilized dredge materials (SDM) as thecoefficient of consolidation (Cv) value decreases with increasing consolidation pressure.

Free mica particles in crushed rock aggregates for constructional purposes affect the quality of the end product. It is also known that mica-bearing rocks may cause damages of the road constructions, especially in regions with a temperate climate. The negative influence arises in both bounded and unbounded layers. The deterioration of the construction is related to the ability of mica particles to be released during crushing and to concentrate in the aggregate fine fractions. As the free mica particles absorb and hold liquid such as bitumen and water, the unbounded base course becomes susceptible to frost weathering and the mechanical properties of the asphalt mixture are negatively influenced. The water absorption ability is in turn caused by an increased specific surface area of the fine fraction depending on the grain shape of mica particles and their intra crystalline cavities. The aim of the present study was to investigate, emphasise, and contribute to an understanding of the performance of free mica particles in the fine fractions of crushed rock aggregates. The free mica problems are well- known, but sparsely taken into account in projecting and prospecting activities. The mineralogical composition (i.e. the quality) of the rock material is often a subordinated task in early stages in planning for roads and railways. Connected with establishment of quarries the estimation of rock materials quality is generally based on petrographic and mechanical analyses of drill-cores.The study presented consists of: * The investigation of the ability of free mica particles to enrich in fine fractions of granitoid crushed rock aggregates. The comparison study to examine a possible correlation between the content of mica in original rock materials, the content of free mica particles in rock aggregate products, and the content of free mica particles in drill cuttings. * The development of a method to estimate free mica particles in aggregate fine fractions using image analysis of grain mounts. * The development and practical applicability of a method to estimate rock aggregates quality using analyses of drill cuttings. The study reveals that mica-bearing rocks exposed to mechanical impact release free mica particles that concentrate in the fine fractions of crushed rock aggregates. The original grain size of mica in the host rock is suggested to influence on the process. Coarse-grained rocks seem to separate free mica grains in earlier phases of the crushing process than fine-grained ones. The enrichment is suggested to depend on the textural characteristics of the rock rather than on the mineralogical composition. These aspects must be taken into consideration when the grain size fractions for analyses of free mica content are selected. The statistical evaluation of the new method for estimation of free mica particles points out its certainty and repeatability. Due to the possibility to save the images of the statistical operation, the results of the method are controllable. These factors mentioned make the method satisfactory and statistically acceptable from a scientific point of view. The concept using drill cuttings for estimation of rock aggregates quality is practically tested and evaluated as an effective field method. The further development and calibration should focus on improvement of sampling concerning the content of coarse drill cuttings. The homogeneity/heterogeneity of the bedrock is crucial for the selection of the samples and stresses the necessity of representative sampling. / <p>Godkänd; 2008; 20080521 (ysko)</p>

The thesis presents series of laboratory studies of aggregates containing mica minerals obtained from aggregate producers located throughout Sweden. The main idea of the research was to study physical properties and behaviour of free mica particles in unbound granular products of crushed rock materials. Another objective was to highlight the detrimental properties of mica occurrence in aggregates used for road construction industry and determine the applicable methods for quantitative determination of mica minerals presence. Due to the lack of previous investigations looking at this or similar subject, the current research can have international importance, especially for countries with crystalline, mica rich bedrock and temperate, subarctic climates. Recently a number of cases involving road construction failures and decrease in service life have been observed in northern parts of Sweden. One of the major reasons for the structural deterioration was enrichment of free mica particles in aggregates and their interaction with water. Due to this reason first paper of this thesis represents a study of the behaviour of free mica grains in crushed rock aggregates of metamorphic origin and recognition of any trend of enrichment of free mica grains aggregates. As a result two general trends of enrichment of mica were obtained: Type I (isotropic source rock) and Type A (anisotropic source rock). Type I is exemplified by a general increase of free mica towards finer grain fractions, with or without a peak for "coarser" grain fractions. Type A represents an increase of free mica up to a certain grain fraction, thereafter no increase occurs towards finer grain fractions. Second part of the thesis focuses on the determination of the possible analytical methods which are susceptible to mica content and could be used as indicating technique for quantitative determination of free mica particles in unbound granular materials. Two standard methods: Sand equivalent test and Methylene blue test were assumed as the most sensitive to mica presence. Both methods showed susceptibility to mica content and gave strong correlation in terms of mica content. The third paper enhances knowledge of the behaviour of mica rich aggregates in interaction with water in terms of fraction sizes and free mica content. During the experiment several aggregates with different content of free mica and pure mica material consisting of commercial biotite were studied. Two major parameters were investigated during the research: water storage capacity and specific water saturation value. With the aid of consecutive analytical and statistical analyses a more precise mica presence threshold value for certain unbound applications was indicated, resulting in recommendations for industry, authorities and for future experiments. / <p>Godkänd; 2008; 20080616 (ysko)</p>

<p>QC 20150311</p>

Vibratory rollers are commonly used for compaction of embankments and landfills. In a majority of large construction projects, this activity constitutes a significant part of the project cost and causes considerable emissions. Thus, by improving the compaction efficiency, the construction industry would reduce costs and environmental impact. In recent years, rollers have been significantly improved in regard to engine efficiency, control systems, safety and driver comfort. However, very little progress has been made in compaction effectiveness. While the compaction procedure (e.g. layer thickness and number of passes) has been optimized over the years, the process in which the machine compacts the underlying soil is essentially identical to the situation in the 1970s. This research project investigates the influence of one crucial parameter, namely vibration frequency of the drum, which normally is a fixed roller parameter. Frequency is essential in all dynamic systems but its influence on the compaction efficiency has not been studied since the early days of soil compaction. Since laboratory and field equipment, measurement systems and analysis techniques at the time were not as developed as they are today, no explicit conclusion was drawn. Frequencyvariable oscillators, digital sensors and computer‐based analysis now provide possibilities to accurately study this concept in detail. In order to examine the influence of vibration frequency on the compaction of granular soil, small‐ scale tests were conducted under varying conditions. A vertically oscillating plate was placed on a sand bed contained in a test box. The experiments were carried out in laboratory conditions to maximize controllability. The first test setup utilized an electro‐dynamic oscillator where dynamic quantities, such as frequency and particle velocity amplitude, could be varied in real‐time. The second test setup included two counter‐rotating eccentric mass oscillators, where tests were conducted at discrete frequencies. This type of oscillator has a force amplitude that is governed by frequency. The main objectives of the tests were to determine the optimal compaction frequency and whether resonance can be utilized to improve compaction efficiency. Results showed that resonance had a major influence in the electro‐dynamic oscillator tests, where the applied force amplitude is low, and the optimal compaction frequency is the resonant frequency under these circumstances. In the rotating mass oscillator tests, where a high force was applied to the plate, resonant amplification was present but not as pronounced. Since force increase with frequency, the optimal frequency to obtain the highest degree of compaction is very large. In a practical regard, however, frequency should be kept as low as possible to minimize machine wear and emissions while still achieving a sufficient compaction of the soil. Considering the practical issues, it is proposed that surface compactors should operate slightly above the resonant frequency. However, the applicability to vibratory rollers must be confirmed in full‐scale tests. The thesis also presents an iterative method to calculate the frequency response of a vibrating plate, incorporating strain‐dependent soil properties. Calculated dynamic quantities are compared to measured values, confirming that the method accurately predicts the response. / <p>QC 20140129</p>

<p>QC 20150610</p>

No description available.

No description available.