Project purpose. This project scope includes testing of the road bitumen adhesion to a stone material at low temperatures that will allow for assessment of the adhesion determination standard methods applicability for this temperature range. The same conditions will be used to study morphology of the stone material surface after the adhesion bond collapse.
State of the art in the field. Due to increasing transportation load requirements for the quality of the bitumen binder and durability of a pavement increase accordingly.
At a certain stage improvement of the bitumen quality has been constrained by current effective engineering standards related to the road bitumen, mainly based on the empirical methods and test results obtained at the experimental temperatures that quite significantly differed from the actual road surface operation temperatures. It is therefore that an upgraded «Superpave» road bitumen testing system providing for the bitumen test methods maximally close to the bitumen road operational conditions has been developed in the US. However, «Superpave» does not include any new methods and techniques used to determine bitumen adhesion to the stone material surface though experts think that this indicator impacts the asphalt operational properties.
Conventionally in Kazakhstan, as well as other countries, adhesion of bitumen to any stone material is determined by its boiling in water. The same technique is used to estimate the efficiency of the adhesion additives effect on bitumen. Any other standard methods of the adhesion assessment require its testing at room temperature. However it has not been yet proved whether obtained data really correspond to the real adhesion value at low temperature.
Expected results and their application. As a result of this project implementation, it is expected to get new data on the specific features of a binding agent adhesion to materials of various chemical nature at low temperatures. Obtained data can be applied to assess legitimacy of using standard adhesion determination methods within a wide temperature range.
The results of the project can be used to create compositions of the binding agents with improved adhesion properties and more durable asphaltic concrete mixtures.Scope of activities. The following basic works will be carried out within the project scope:
- Installation of a complete set of the equipment and its start-up to test standard methods of determining adhesion of bitumen to the stone material;
- Modification of the standard techniques of the bitumen adhesion determination to apply them to low temperatures;
- Determination of adhesion values of the road bitumen of different grades to the alkaline and acidic stone material;
- Determination of effect of adhesion and polymer additives in bitumen on the value of adhesion to the stone material;
- Study of morphology of the stone material surface after bitumen separation using the SEM method;
- Carrying out comparative analysis of the data on the different binding agents adhesion change that occurs when temperature decreases.
