The water resistance of a recycled base with foamed bitumen in the aspect of road binder composition

The paper describes research results of recycled base which was performed
in a cold deep recycling technology with foamed bitumen and different type of hydraulic
mixed binder in the aspect of water resistance. An individual design of a composition of a
binder enables to achieve a precise adjustment of a binder’s impact to local conditions and
required parameters of a recycled base. The design a recycled base with foamed bitumen
simulated a cold deep recycling process with materials from existing crushed bituminous
pavement layers ("technology in-situ"). To produce the foamed bitumen a road bitumen of
penetration grade 50/70 was used. Moreover, the following mineral components were
categorised as a waste material: reclaimed asphalt pavement, 0/31,5 mm aggregate and
aggregates for soil gradation improvement 0/4. A composition of the recycled base consisted of the binders prepared in the laboratory as a result of a mix of three basic components.
The percentage of individual road binders was determined in line with the plan of the
simlex-centroid experiment. For the purpose of determining an influence of such a hydraulic
road binder on the water resistance in recycled base, the following tests were carried out:
void contents Vm, tensile strength ratio TSR (water resistance). Additionally, an evaluation
of increase of indirect tensile modulus (IT-CY) was conducted. On the basis of the test
results, a varied impacts of tested hydraulic road binders on mechanical properties and
water resistence of recycled base with foamed bitumen were observed. On the basis of the
plan of the experiment, it was possible to determine the recommended road binder composition that enabled to obtain the water resistance in the recycled base with foamed bitumen