Since several years research in the field of crumb rubber modified bitumen (CRMB) is again an important area of interest. This fact is driven by restrictions for land-filling of old tires and their energetic use as a solid fuel e.g. in cement production. At the same time some experts expect that the use of higher content of crumb rubber in bitumen can further decrease the noise reducing potential if used in suitable acoustic asphalt mixes. Last but not least using crumb rubber as a modifier creates on the market binder which would fill the application gap between distilled bitumen and PMBs. Within the research done at Czech Technical University in Prague different types of micro-pulverized rubber has been used together with chemical
catalysts suitable for temporary devulcanization of the rubber. Further for improving the homogeneity and storage stability of the CRMB additional additives have been tested and their effects compared. For the bitumen samples traditional as well as performance-based tests
have been done. Within the traditional test softening point, penetration and elastic recovery test should be stressed out. For performance-based testing dynamic shear rheometer has been used for running frequency sweeps for temperatures between 20 and 60°C. At the same time multiple stress creep recovery test has been done for test temperature of 60°C. Dynamic viscosity has been assessed as well. Paper summarizes gained findings and recommendations made for most suitable combinations of bitumen – CR content – catalyst and additive.

crumb rubber modified bitumen, pulverized rubber, chemical catalysts, penetration, complex shear modulus, storage stability, elastic recovery