**2. Pyrolytic product for the purpose of rejuvenation**

Pyrolytic products in the research were obtained by the process of slow pyrolysis. In the first phase, the conditions of the pyrolysis process e.g. the duration (from 10 min to 150min) and the pyrolysis temperature (from 280–500°C) were changed in order to obtain different pyrolytic products. In the second phase, the pyrolytic products were modified with various oils and crushed rubber. All composed pyrolytic products were similar to bitumen. Their properties and properties of their blends with reference bitumen were evaluated by standard European mechanical tests, which are usually used to determine the properties of bitumen. As reference bitumen and as a matrix of the blends a 50/70 penetration grade bitumen (B50/70) was used. All the blends were laboratory produced by adding a controlled quantity of the pyrolytic product to the bitumen. The blends of bitumen and pyrolytic product were commonly produced by mixing two of the components in ratios of 1:1 (labelling them B+No. of pyrolytic product). Only the blends of pyrolytic product No. 11 were also prepared in smaller concentrations (11\_x%, where x represents a share of the pyrolytic product).

*Rejuvenator Obtained by Pyrolysis of Waste Tires for Use in Asphalt Mixtures with Added… DOI: http://dx.doi.org/10.5772/intechopen.99490*

The softening properties were determined by using the Ring and Ball method (RB) according to the EN 1427 [23]. Fraass breaking point test according to the EN 12593 [24] was used to determine the brittleness of the products at low


### **Table 1.**

*Results of standard mechanical tests of pyrolytic products and their blends with reference bitumen [20].*

temperatures. The tensile properties of the bitumen and pyrolytic products were determined by the force ductility method in accordance with EN 13589 [25].

For the production of asphalt, it is important to determine the optimum mixing temperature for specific bitumen, which is the temperature to be maintained at the asphalt plant during mixing. For laying of asphalt the compaction temperature, at which the mixture has to be compacted on sites has to be determined. The mixing and compaction temperatures for pure pyrolytic rejuvenators and bitumen blends were determined with the rotational viscometer Haake RS50. Both temperatures determine recommended viscosity of bitumen: 0.170 ± 0.02 Pas form mixing and 0.260 ± 0.03 Pas for compaction, respectively [26].

Results in **Table 1** show most pyrolytic products lowered the softening point of the blends in comparison with reference bitumen. That means the pyrolytic product could also lower the high softening point of the extracted bitumen in reclaimed asphalt. For our product, this is a good feature, as we want to use it as a rejuvenator. In addition, almost all pyrolytic products lowered the Fraass breaking point, meaning the temperature range is extended.

Results of final elongation at force ductility tests show that all pyrolytic products broke before they reached the maximum possible length (1500 mm, designated 1500\* in **Table 1**) to the contrary of reference bitumen. The pyrolytic products 4, 5, 7, 8, 9, 10, and 11 (in adequate concentration) retained the elongation ability of the reference bitumen in the blends. All other pyrolytic products shortened the elongation of the blends. Except for the pyrolytic product no. 8, all other values of


**Table 2.**

*Results of viscosity measurements of the blends (pyrolytic products with reference bitumen) [21].*

*Rejuvenator Obtained by Pyrolysis of Waste Tires for Use in Asphalt Mixtures with Added… DOI: http://dx.doi.org/10.5772/intechopen.99490*

maximum force measurements were in the range around 1 N or even smaller. The ductility test was performed at 25°C for the pyrolytic products (and their blends) from 1 to 8. For others, the test temperature was lowered, to 15°C. Pyrolytic product 11 and its blends, B+11 and 11\_20%, could not be tested even at the temperature of 15°C, so we did no performed test for those three samples.

The results of the mixing and the compaction temperatures of the pyrolytic products are higher than the reference bitumen's. Although this indicates that the pyrolytic products have a higher viscosity, also the homogeneity of the sample influenced the viscosity. Inhomogeneous samples (2, 9, 10, and 11) have higher viscosity. Blends of pyrolytic products 7, 10, 11 and 14 have lower mixing and compaction temperatures.

The viscosity of the blends was determined at three different temperatures and was measured at the constant shear rate. Results (**Table 2**) show that the viscosity of the bitumen and the blends is decreasing with increasing temperature. In general, the viscosity of all blends is lower than the viscosity of the references bitumen at 60 °C and 100°C. At 150°C viscosity of almost all blends was at least as high as the reference's bitumen; nevertheless, the absolute values of the viscosity were very small.

Based on the results of these tests we decided that out of the fourteen manufactured and modified pyrolytic products, the most suitable pyrolytic product for the role of a pyrolytic rejuvenator was number 14.
