I kallasfalt med hårt basbitumen bryter vattnet ut ur bitumenet och bindemedlet i massan stelnar olika snabbt beroende på vilket stenmaterial asfaltsmassan består av. Om brytningen sker innan utläggning blir massan obearbetbar, målet är att brytningsprocessen ska kunna styras genom att massans brytningsprocess skall vidta när energi tillförs i massan via en vibratorsvält som packar massan. Från tidigare tester är hypotesen att det är stenmjölet som styr brytningsprocessen och bearbetbarheten. Idag är problemet att massan bryter för snabbt och den blir svårbearbetad vid läggning och resultatet blir dåligt. I arbetet undersöks också täckningsgrad och styvhetsmodulen. Arbetet är utfört på NCC:s väglaboratorium i Umeå 4/4 - 15/4 2016. Sex stycken stenmaterial från olika bergtäkter med olika egenskaper testas. Bergtäkterna är belägna från Närke upptill Västerbotten vid namn Dylta, Råsta, Sälgsjön, Stöningsberget, Ljusberget och Supartallen.  Fraktion 0-16 mm från en och varje bergtäkt handblandas, två asfaltsprover tillverkas enligt två olika mix- och bedömningsmetoder. Täckningsgrad, bearbetningsegenskaperna och brytningprocessen bedöms och antecknas i en matris. I nästa steg ersätts ordinarie stenmjöl (0-2 mm) med stenmjöl från en bergtäkt med ett tidigare känt bra stenmaterial. Med resterande makadam (2-16 mm) görs samma process om på nytt och resultatet analyseras och jämförs. En asfaltsmassa med stenmjöl från bergtäkten Supartallen och makadam från bergtäkten Stöningsberget visar förbättrade resultat i jämförelse med fraktion 0-16 mm från bergtäkten Stöningsberget och vidare laborationstester görs på denna blandning av stenmaterial. Dessa bergtäkter ligger geografiskt nära varandra, drygt 25 mil, vilket också motiverar till att välja dessa stenmaterial som i framtiden kanske kommer användas fullskaligt. Från dessa blandningar tillverkas asfaltskroppar genom packning med gyratorisk packare och styvhetmodulen testas. I ekonomisk och miljömässig vinning görs ett försök med en restprodukt från stålindustrin. Ett försök utförs med skänkslagg (0-2 mm). Slaggen blandas med stenmaterial från bergtäkten Supartallen där bearbetningen, brytprocessen och täckningsgraden undersöks. Detta är ett inledande försök för att få en fingervisning hur asfaltsmassan beter sig blandat med skänkslagg. Utvärdering av resultaten gjordes med hjälp av en matriser där varje asfaltsblandning ingår. Asfaltsblandningen betygsätts enligt bearbetbarhet, täckningsgrad och brytningskontroll. Skålen analyserades och slutsatser om brytningen kunde dras. Genom sönderdelning av massan kunde observationer göras om hur brytningen av massan har kommit, även täckningsgraden analyseras. Resultaten pekar på att stenmjölet har en betydande roll i täckningsgrad, brytning vid blandning och brytningsprocessen, dock ingen skillnad på styvhetsmodulen. Att enbart stenmjölet ska vara problemet är inte hela sanningen men har som sagt en betydande roll. Just att stenmaterial från Supartallen är så pass bra för beaktas och använda sig av stenmaterial med liknande egenskaper och inte använda stenmaterial med för höga halter SiO2 då det ger dålig täckningsgrad. Att massan bryter för snabbt kan bero på halten bindemedel, vidare laborationer bör göras med halten bindemedel i fokus. / In cold asphalt with hard base-bitumen the water breaks out from the bitumen and the binder in the mass solidifies at different rates depending on the containing stone material in the asphalt. If the break occurs before laying the mass becomes unworkable. The intention by this examination is control this process by the mass extraction process should take place when energy is supplied into the mass through a vibrator famine. From previous tests the hypothesis is that the rock flour controls the breaking-process and the workability. Today, the problem is that the mass curing process starts too early and it becomes difficult to manage and work with and the results of the paving are bad. The thesis project also examines coverage and stiffness module, it’s performed on the NCC's road laboratory in Umeå 4/4 - 15/4 in 2016. Six stone materials from different quarries with different properties are tested. Fraction 0-16 mm from each rock quarry are handmixed, two asphalt samples produced by two different mixing- and assessment-methods. Coverage, workability and the breaking-process are assessed and recorded in a matrix. Next, replaced ordinary rock flour (0-2 mm) with rock flour from a quarry of a previously known good stone material. With the remaining makadam (2-16 mm) the process are made all over again and the results are analyzed and compared. An asphalt with rock flour from quarry Supartallen and the remaining makadam from quarry Stöningsberget shows improved results compared with fraction 0-16 mm from quarry Stöningsberget and further tests in laboratory are made with this mixture. These quarries are geographically fairly close to each other, 250 km (about 150 miles), which motivates to choose these quarries for a full scale-test in the future. From these mixtures asphalt-bodies are manufactured by gasket with gyratory compactor and stiffness module is examined. In the economic and environmental profit attempts are made with a residue from the steel industry. An attempt carried out with the slag from ladles (0-2 mm). The slag is mixed with stone material from quarry Supartallen where workability, breaking process and coverage is investigated. This is an initial attempt to introduce how the asphalt mixture behaves mixed with the slag. An evaluation was made with matrix where each asphalt mixture included. The asphalt mixture is graded according to machinability, coverage and breaking control. The bowl was analyzed and conclusions about the break could be drawn. Analyzes of the curing process and coverage was made by dismemberment of the mass. The results indicate that the rock flour has a significant role in coverage, extraction at mixing and mining process, however, the stiffness module has the same results in all mixtures. The mere stone flour shouldn’t be the problem but still has a significant role. At the aggregate of Supartallen is so good for the consideration and use of stone materials with similar properties and not rock material with a high amount of SiO2 as it provides poor coverage. The mass harden too quickly may depend on the content of binder, further laboratory work should be done with the binder content in focus.

Asphalt joints are inevitable parts of every pavement. They are constructed for different reasons. Although much attention is dedicated to the construction joints (hot with hot pavement), a scientific approach for cold joints (cold with hot pavement) with respect to large patch constructions is still missing. This report tries to evaluate existing construction techniques and to suggest new testing methods of tests. Although, indirect tensile tests IDT and direct tension tests DTT are familiar in the field of asphalt pavement characterization, they have not been used for the assessment of joint quality so far. In this report, these two test types are evaluated and the results are analyzed using finite element software ABAQUS. The results of the comparison of joint compaction techniques on a laboratory scale suggest that joints with angles seem to show more promising behavior than vertical joints. Also, starting compaction from the hot side generally produces better results than compaction starting from cold side.

Currently it is important to address the re-use of building materials from construction reconstructed or upgraded roads. Commonly used technologies cold and hot asphalt recycling are starting using to complement with technologies using cold asphalt mixtures with rejuvinators or softeners. This type of asphalt mixtures could be used in pavement constructions with lower traffic load. This thesis deals with the design and laboratory assessment of unbound and bound mixtures R-material and recycled concrete. This thesis is experimentally testing the possibility of using functional tests to optimize the design of asphalt mixture with 100% representation of R-material with a possible revival of asphalt emulsion with a rejuvenator.

Cold mix asphalt (CMA) emulsion technology could become an attractive option for the road industry as it offers lower startup and equipment installation costs, energy consumption and environmental impact than traditional alternatives. The adhesion between bitumen and aggregates is influenced by diverse parameters, such as changes in surface free energies of the binder and aggregates or the presence of moisture or dust on the surface of aggregates, mixing temperatures, surface textures (including open porosity), nature of the minerals present and their surface chemical composition, as well as additives in the binder phase. The performance of cold asphalt mixtures is strongly influenced by the wetting of bitumen on surfaces of the aggregates, which is governed by breaking and coalescence processes in bitumen emulsions. Better understanding of these processes is required. Thus, in the work this thesis is based upon, the surface free energies of both minerals/aggregates and binders were characterized using two approaches, based on contact angles and vapor sorption methods. The precise specific surface areas of four kinds of aggregates and seven minerals were determined using an approach based on BET (Brunauer, Emmett and Teller) theory, by measuring the physical adsorption of selected gas vapors on their surfaces and calculating the amount of adsorbed vapors corresponding to monolayer occupancy on the surfaces. Interfacial bond strengths between bitumen and aggregates were calculated based on measured surface free energy components of minerals/aggregates and binders, in both dry and wet conditions. In addition, a new experimental method has been developed to study bitumen coalescence by monitoring the shape relaxation of bitumen droplets in an emulsion environment. Using this method, the coalescence of spherical droplets of different bitumen grades has been correlated with neck growth, densification and changes in surface area during the coalescence process. The test protocol was designed to study the coalescence process in varied environmental conditions provided by a climate-controlled chamber. Presented results show that temperature and other variables influence kinetics of the relaxation process. They also show that the developed test procedure is repeatable and suitable for studying larger-scale coalescence processes. However, possible differences in measured parametric relationships between the bitumen emulsion scale and larger scales require further investigation. There are several different research directions that can be explored for the continuation of the research presented in this thesis. For instance, the rationale of the developed method for analyzing coalescence processes in bitumen emulsions rests on the assumption that the results are applicable to large-scale processes, which requires validation. A linear relationship between the scales is not essential, but it is important to be able to determine the scaling function. Even more importantly, qualitative effects of the investigated parameters require further confirmation. To overcome the laboratory limitations and assist in the determination of appropriate scaling functions further research could focus on the development of a three-dimensional multiphase model to study coalescence processes in more detail, including effects of surfactants, pH and other additives such as mineral fillers and salts. Additionally, better understanding of the breaking process and water-push out could help significantly to optimize CMA mix design. Different methods, both numerical and experimental could be explored for this. / Cold mix asphalt (CMA) eller kall asfaltbetong med hjälp av emulsionsteknik kan vara ett attraktivt alternativ för vägbyggnadsindustrin då det möjliggör lägre uppstart- och investeringskostnader, lägre energiförbrukning och mindre miljöpåverkan än traditionella alternativ. Adhesionen mellan bindemedel och stenpartiklarna påverkas av ett flertal parametrar, så som förändring i fri ytenergi hos både bindemedel och partiklar i närvaro av fukt eller damm på stenytorna, blandningstemperatur, yttextur (inklusive ytporositet), mineralegenskaper och ytornas kemiska sammansättning lika väl som tillsatsmedel i bindemedlen. Beteendet hos kall asfaltbetong är starkt påverkad av vätningsegenskaperna hos bindemedlet när det kommer i kontakt med stenmaterialet och detta i sin tur är beroende på bitumenemulsionens brytegenskaper och förmåga att blandas. Bättre förståelse av dessa processer är av största vikt. I detta arbete är avhandlingen baserad på fri ytenergi hos både mineraler/aggregat och bindemedel, baserat på kontaktvinkel och på ångabsorptionsmetoder. Den exakta specifika ytan hos fyra typer av aggregat och sju mineraler undersöktes med en metod baserad på BET (Brunauer, Emmett och Teller):s teorier genom att mäta den fysiska adsorptionen av utvalda gaser på ytorna och beräkna mängden adsorberad ånga som korresponderade mot ytlagret. Styrkan hos kontaktytornas bindning mellan bindemedlet och stenaggregaten beräknades baserat på mätningar av den fria ytenergin hos bägge ingående komponenterna, dels i torrhet dels i våta omgivningar. Som tillägg har en ny experimentell metod utvecklats för att studera bitumens blandbarhet genom att studera bitumendroppars relaxation i en emulsionsmiljö. Genom att använda denna metod har korelationen mellan sväriska droppar av bitumen undersökts mot förändringen i ytans area under blandningsprocessen. Testprotokollet utformades för att studera blandningsprocessen i varierande miljöer i en klimatkammare. Presenterade resultat visar att temperatur och andra variabler påverkar de kinetiska förhållandena vid relaxationsprocessen. De visar även att den utvecklade testmetoden är repeterbar och passar för studier av storskaliga blandningsprocesser. Det bör dock påpekas att vidare studier krävs för att påvisa skillnaderna mellan bitumenemulsionsskalan och större skalor. Framtida forskning kommer att koncentreras på utveckling av tredimensionella multifas­modeller för att studera blandningsförlopp på en mer detaljerad nivå, inkluderande effekter på ytaktiva ämnen, pH-värden och andra additativ så som mineralfiller och salt. Som tillägg kommer nyttan av nya karaktäriseringsmetoder att utvärderas, så som lågvikelspridning av neutroner eller kombinationer av röntgen, neutronradiologi och datortomografi, för att studera brytmekanismer hos bitumenemulsioner vid kontakt med mineraler och aggregat. / <p>QC 20160901</p>

Asphalt joints are potentially weakest parts of every pavement. Despite of their importance, reliable tools for measuring their mechanical properties for design and performance assessments are still scarce. This is particularly true for cold joints when attaching a new hot pavement to a cold existing one as in case of large patches for pavement repair. In this study, three static fracture testing methods, i.e. indirect tensile test (IDT), direct tension test (DTT) and 4 point bending (4PB), were adapted and used for evaluating different laboratory made joints. The results suggested that joints with inclined interfaces and also the ones with combined interface treatments (preheated and sealed) seemed to show more promising behaviors than the vertical and untreated joints. It was also confirmed that compacting from the hot side towards the joint improved the joint properties due to imposing a different flow pattern as compared to the frequent compaction methods. The latter finding highlighted the importance of asphalt particle rearrangements and flow during the compaction phase as a very little known subject in asphalt industry. Studies on compaction are of special practical importance since they may also contribute to reducing the possibility of over-compaction and aggregate crushing. Therefore, in this study, a new test method, i.e. Flow Test (FT), was developed to simulate the material flow during compaction. Initially, asphalt materials were substituted by geometrically simple model materials to lower the level of complexity for checking the feasibility of the test method as well as modeling purposes. X-ray radiography images were also used for capturing the flow patterns during the test. Results of the FT on model materials showed the capability of the test method to clearly distinguish between specimens with different characteristics. In addition, a simple discrete element model was applied for a better understanding of the test results as a basis for further improvements when studying real mixtures. Then, real mixtures were prepared and tested under the same FT configuration and the results were found to support the findings from the feasibility tests. The test method also showed its potential for capturing flow pattern differences among different mixtures even without using the X-ray. Therefore, the FT was improved as an attempt towards developing a systematic workability test method focusing on the flow of particles at early stages of compaction and was called the Compaction Flow Test (CFT). The CFT was used for testing mixtures with different characteristics to identify the parameters with highest impact on the asphalt particle movements under compaction forces. X-ray investigations during the CFT underlined the reliability of the CFT results. In addition, simple discrete element models were successfully generated to justify some of the CFT results. / <p>QC 20151104</p>