Asphalt Binder Modification with Plastomeric Compounds Containing Recycled Plastics and Graphene

Polymer-modified bitumens are usually employed for enhancing the mixture performance against typical pavement distresses. This paper presents an experimental investigation of bitumens added with two plastomeric compounds, containing recycled plastics and graphene, typically used for asphalt concrete dry modification. The goal was to study the effects of the compounds on the rheological response of the binder phase, as well the adhesion properties, in comparison with a reference plain bitumen. The blends (combination of bitumen and compounds) were evaluated through dynamic viscosity tests, frequency sweep tests, and multiple stress creep recovery (MSCR) tests. Moreover, the bitumen bond strength (BBS) test was performed to investigate the behavior of the systems consisting of blends and aggregate substrates (virgin and pre-coated). The rheological tests indicated that both blends performed better than the plain bitumen, especially at high temperature, showing an enhanced rutting resistance. In terms of bond strength, comparable results were found between the blends and reference bitumen. Moreover, no performance differences were detected between the two types of blends.

A review of the best experience on crumb rubber – dry process modified asphalt mixture performance

The use of crumb rubber made from end of life tyres for asphalt mixtures modification in order to improve their properties or just utilize waste products may be considered as potential solution. Crumb rubber can be used as a bitumen modifier (wet process) or supplementary component of the asphalt mixture (dry process). Dry modification process has more potential due relatively unsophisticated technology and higher possible to use amount of crumb rubber comparing to the wet process. The performance of asphalt mixtures modified by dry process mainly depends on several factors as crumb rubber type, content and size. However, limited number of publications reported the results of dry method crumb rubber modified asphalt mixtures performance. This paper summarizes the latest findings from literature review on the modification technologies and specifications related to dry modification process, the effect of crumb rubber type and amount on modified asphalt mixture performance in terms of stiffness, rutting resistance, water sensitivity, resistance to fatigue and low temperature cracking. The algorithm of crumb rubber modified asphalt mix design was introduced.

Study on the Surface Modification of Nanometer Calcium Carbonate

Titanate coupling agents KR-TTS is used to modify nanometer calcium carbonate and the modified powder is characterized. The modification mechanisms of nanometer calcium carbonate is also investigated in this paper. Experiment results show that the optimum conditions of dry modification method as follows: the dosage of KR-TTS titanate coupling agents is 2%, mass ratio of KR-TTS titanate coupling agents to liquid organic solvent is 1:1, modification temperature is 70°C, modification time is 20 minutes, stirring rate is 650rpm. Under the optimum conditions, activity index of modified nanometer calcium carbonate is 100%. The activity index Measurement indicates that modified nanometer calcium carbonate become hydrophobic instead of hydrophilic. IR analysis shows that chemical bonds are formed between titanate coupling agents and nanometer calcium carbonate particles.