Influence of mixed hydraulic binder on the properties of recycled asphalt mixtures with foamed bitumen

Developments in reconstruction of roads of all categories - from motorways to local roads - result in production of large quantities of reclaimed asphalt pavement (RAP) material of various quality and grading. In a sustainable economy, it is necessary to recycle such materials. Currently RAP is primarily reused in recycled mixtures dedicated for road base courses. Variable quality of RAP material requires application of appropriate binding agents to optimize the performance of the obtained mixtures. There is a need for dedicated three-component hydraulic binder, consisting of CEM I 32.R cement, hydrated lime Ca(OH) 2 and cement by-pass dust (CBPD), whose proportions should be adopted adequately to the intended use. The influence of hydraulic binder composition was investigated for the following parameters of the obtained mixture with foamed bitumen: air voids, indirect tensile strength, uniaxial compressive strength, resistance to water and frost (according to four different parameters) and stiffness moduli at -10 degrees C, +13 degrees C, +25 degrees C and +40 degrees C in accordance with the IT-CY method. The recommended composition of the three-component binder providing the required properties of cold-recycled mixture with hydraulic binder and foamed bitumen was determined based on the obtained test results.