Förbättring av asfaltens konsistens med tillsatsmedel - Mätningar med rotationsviskosimeter på bitumen och asfaltsbruk

Sammanfattning: Asphalt is the most common material on the roads visible to our eyes. Asphalt occurs as both wearing coat and bearing coat. Asphalt consists of rock material in different grain sizes joined by a binder, bitumen, and eventually added additives. Bitumen is extracted from crude oil. Asphalt mastics is bitumen mixed with filler. Filler is stone material that completely passes a 0.074 mm sieve. Both bitumen and rock are finite resources. The interest in recycling asphalt is increasing, but problems arise on the way. The goal is to increase the recycling of recycled asphalt in newly manufactured asphalt without deteriorating the quality of the finished product. Also, the goal is to increase the sustainability of the asphalt and reduce the environmental impact that asphalt contributes to. In order to produce asphalt mass, large amounts of energy are needed in form of heat that contributes to carbon dioxide emissions. Another problem that arises is overheating when recycling asphalt since recycled asphalt (RAP) and recycled bitumen require more heat to be processed. A research area that has made progress in the development of better, durable and stronger asphalt coatings is the production of various additives that are supplied in the manufacture of asphalt. There are many reasons why additives are used in asphalt manufacturing. The additives used in this project are in the form of wax and act as temperature reducers, as well as fluids that act as rejuvenating agents. The temperature reducing additives investigated in this report are: Sasobit, Redux, ZycoTherm and Rediset LQ-1102CE. The rejuvenating agents investigated in this report are: STORFLUX, Sylvaroad RP1000 and Nygen 910. Additives were investigated together with pure bitumen, recycled bitumen, pure asphalt mastic and recycled asphalt mastic. They were examined using a Brookfield RVB rotational viscometer in a laboratory at LTH, Lund. A total of 28 samples were investigated with RVB. The machine is specially designed to measure viscosity, i.e. internal friction of the fluid, in fluids. Therefore, the RVB has been selected for this project, because bitumen and asphalt mastic are classified as fluids. RVB can also measure the Soft Point and have a higher precision in the measurements than old test methods such as Ball & Ring or Penetration. Additionally, the Ball & Ring method cannot measure the Soft point of asphalt mixtures, such as asphalt mastics, but only for pure bitumen. What was investigated was how the additives affect the consistency of the binder and asphalt mastics, i.e. the effect on the binders and mastics viscosity. The results were presented graphically in Heukelom BTCD chart there series of measurement points were bonded to viscosity lines. The BTDC chart shows how the viscosity and temperature relate to each other and how different bitumen occurs at the same temperatures. Initially, the study began with a preliminary study on asphalt mastics where viscosity measurements were carried out on asphalt mastics with different amounts of filler. The initial study was made to gain an insight into how the asphalt mastics reacts with the RVB machine and to find an appropriate composition of the asphalt mastics that could be considered to represent an ordinary asphalt type. In the initial study, we would also measure the stiffening effect of filler on bitumen. The result of the preliminary study became a filler volume of 36.3 vol%, which also represents the asphalt type ABS 11. The amount of filler that was determined from the preliminary study was the amount with which the research continued with. Additives, which claim the possibility of lowering the temperature with 25-30 ° C in the mixture, had a small effect on the viscosity of bitumen. Asphalt mastic reacted a bit more to the additives but not enough to substantiate the claim. This may be due to the fact that suppliers used other testing methods to test the possible lowering temperature. The rheological effects on bitumen of rejuvenation were quite clear. Although rejuvenated recycled bitumen got newly manufactured properties, recycled asphalt is way more stiffer than newly produced asphalt mass because the filler content (F / B) is still high. The F / B value is the ratio between the amount of filler and bitumen. If the F / B value is high, that means that too much filler is mixed with the bitumen. A given filler type gives a specific F / B value that is unique to different types of fillers. The situation is improved considerably with rejuvenating agents, but it takes a bit more to newly manufactured properties. Since rejuvenating agents reduce the viscosity of the recycled bitumen and recycled asphalt mix, it means that it is easier to handle those with the rejuvenator than without. A positive effect on manageability also means that it is easier to RAP in new production and when asphalt is laid on the roads. Additives contribute to a temperature reduction of about 2-8 ° C according to the results of the study. This is not enough to solve the overheating problem. A functioning temperature-reducing additive could compensate the remaining difference from newly manufactured use. A combination of both temperature-reducing additives and rejuvenating agents can also be a solution to the overheating problem. Keywords: Bitumen, asphalt, viscosity, rotary viscometer, additive