Faktorer som påverkar hanterbarheten hos asfaltsmassa

Sammanfattning: Workability is a description of what ease an asphalt can be worked with during mixing, laying and compaction. The main impacting factors on the workability during the different stages are temperature and the binder properties, a studied report from Nation Center for Asphalt Technology states. This thesis aims to examine how the binder is affected by quality, temperature and additives. To investigate the bitumen properties the most common methods have been used; penetration test and softening point test. A third method was used, which not yet is a standard method for testing of bitumen. The central term throughout all stages is viscosity, which is a measure of a fluid’s internal friction. To measure it we used a viscometer, by the brand Brookfield. The equipment is a of the type dynamic rotational viscometer, DRV, which measures the viscosity by letting an inner cylinder rotate inside of an outer fluid filled container and reading the resulting torque. The equipment may temper the samples from room temperature up to 300 °C. As an effect of the high temperatures for some kinds of bitumen, hazardous fumes are emitted and higher costs arise, which both could be reduced by the use of various additives. Also, the properties of the bitumen could be changed by high temperatures. The main focus in the report is the examination of two types of penetration grade bitumen (50/70 and 160/220), with different additions of the wax-additive Sasobit, from the manufacturer Sasol. By the use of Heukelom diagrams, the viscosity is reported, along with the result of penetration, softening point and kinematic viscosity (read from a capillary viscometer). The latter ones are all known methods, and have in this report been used as reference points to verify the DRV. Among the conclusion is that the softening point can be determined by the DRV, instead of the more frequently used Ring&Ball (R & B) method. The results for pen.bitumen 50/70 and 160/220 shows completely consistent results. That conclusion does not apply when measuring Sasobit or polymer modified bitumen. In those cases, the results from R & B are not trustworthy. When using the additive Sasobit the production temperature can be lowered, while the opposite goes for the polymer modified case. It is known from the field before but with the viscometer results its now also "on paper". The level of knowledge concerning the operation of the DRV was very restricted, when the project started. Thus, a large portion of the work came to circle around finding a good method to record reliable and correct readings.The final method resulted in seven hours of measuring, for each set of measuring. That is, as it implies, highly time consuming, and is a suitable subject for automation in the future. A few trials were performed with reversed direction of measurement (cooling). The results differed from previous ones, and are therefore a suitable subject for further studies.