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The subject of research presented in article was an assessment of the impact of inactive mineral filler content, i.e. dolomite dust, on the recycled cold mix properties with foamed bitumen. The analysis of the impact of dolomite mineral dust was made on the basis of the experiment design type 33. It consisted of three levels of foamed bitumen factor in the range from 1.2% to 3.6% with a 1.2% step and the amount of mineral dust factor in range from 5% to 20% with a 7.5% step. Dolomite dust is a waste material derived from aggregate mining. Foamed bitumen was obtained from foaming process of the neat bitumen 50/70 at water temperature of 25ºC and its amount of 2.7%. In order to increase the cohesion of the recycled cold mix with foamed bitumen, Portland cement CEM I 32.5 R in amount of 2.0% was used. The assessment of the impact of quantitative variables was carried out in accordance with the adopted plan of the experiment that assumed the determination of physical and mechanical properties such as: resistance to climatic factors, dynamic modulus (E*) and phase angle. Analysis of the test results shown that factors quantity affects the variability of analysed features. In the entire scope of experiment plan, the obtained free space values met the requirements in required guidelines. The highest sealing of the recycled mixture was observed for the entire dolomite dust dosage but at maximum amount of foamed bitumen amounted to 3.6%. It was also observed that the maximum water resistance (TSR) was obtained for mixtures with a minimum amount of mineral dust (5%) as well as the maximum amount of dust in the recycled cold mix (20%). However, it was depended of the amount of foamed asphalt in a recycled mixture composition. The study also was considered the influence of the amount of dolomite mineral dust on the change in stiffness modulus tested by means of IT-CY and DTC-CY procedure. It was shown that either stiffness modulus measured by IT-CY or DTC-CY are foam bitumen and dust amount dependent. To assess the rheological properties, the direct compression-compression test (DTC-CY) was used. All samples were subjected to a cyclic sinusoidal constant strain with an amplitude of εo

The paper presents results obtained on the basis of tests carried out using the innovative hydraulic binder intended for a recycled base layer with foamed bitumen. The tested hydraulic binder consisted of three components: cement, hydrated lime and fines. The analysis includes: final time of mortar setting, volume change in mortar, compressive strength after 7 and 28 days of curing, bending strength after 7 and 28 days of curing. The analysis relied in identifying optimal compositions of innovative binder components in terms of its suitability for pavement recycled base layer. Optimisations considered obtaining a two variant such as: quick-setting and a normal-setting hydraulic binder. The analysis of test results indicate that there are solutions for binder compositions that meet the requirements for normal-setting of hydraulically bound base layer in recycled technology. In the scope of obtaining a quick-setting binder, at least 80% of cement binder in the innovative hydraulic binder composition is required.

This article reports the results of numerical simulations of the stress-strain states in the rebuilt road structure compared to the solutions contained in the Polish Catalogue, with the true characteristics of the layer materials taken into account. In the case analysed, a cold-recycled base layer with foamed bitumen as a recycling agent was used. The presented analysis is complementary to the mandatory in Poland procedure of mechanistic pavement design based on a linear elastic model. The temperature distribution in the road structure was analysed at the reference temperature of 40°C on the asphalt layer surface. The loading time was included in the computer simulations through the use of the classic generalized Maxwell model and thus the stiffness-time history of the layers had to be determined. For this purpose, the dynamic modulus E* tests of the loading time frequency from 0.1 Hz to 20 Hz were carried out, and the yield point was modelled using the Coulomb-Mohr failure criterion calculated on the basis of triaxial compression tests. The analytical solution to the problem was found with ABAQUS. The results demonstrate that the high temperature of asphalt layers and long loading time noticeably reduces the stiffness modulus in those layers. That reduction changes the principal stress levels, which significantly influences the shear stress both in the recycled base layer and in the subgrade soil. Should the yield point be exceeded rapidly in the recycled layer, the horizontal stresses in the asphalt layers will increase and adversely affect the durability of the reconstructed road pavement structure, especially in the zones of slow heavy vehicle traffic.

Stiffness modulus is a fundamental parameter used in the modelling of the viscoelastic behaviour of bituminous mixtures. On the basis of the master curve in the linear viscoelasticity range, the mechanical properties of asphalt concrete at different loading times and temperatures can be predicted. This paper discusses the construction of master curves under rheological mathematical models i.e. the sigmoidal function model (MEPDG), the fractional model, and Bahia and co-workers' model in comparison to the results from mechanistic rheological models i.e. the generalized Huet-Sayegh model, the generalized Maxwell model and the Burgers model. For the purposes of this analysis, the reference asphalt concrete mix (denoted as AC16W) intended for the binder coarse layer and for traffic category KR3 (5×105

The article presents the results of a cold recycled mix test with a foam bitumen including the addition of the inactive mineral filler as a dust of basalt. Basalt dust was derived from dedusting system by extraction of aggregates in the mine. Assessment of the impact of a basalt dust on the properties of a recycled base layer was carried out in terms of the amount of mineral filler (basalt) in the composition of the mineral mixture. This experiment involved a dosing of mineral filler in range from 5 to 20% with steps of 7.5% in the mineral mixture composition. The foamed bitumen was performed at optimum foaming process settings (ie. bitumen temperature, air pressure) and at 2.5% of the water content. The amount of a hydraulic binder as a Portland cement was 2.0%. The evaluation of rheological properties allowed to determine whether the addition of inactive mineral fillers can act as a stiffness modulus controller in the recycled base layer. The analysis of the rheological properties of a recycled base layer in terms of the amount of inactive fillers was performed in accordance with given standard EN 12697-26 Annex D. The study was carried out according to the direct tension-compression test methodology on cylindrical samples. The sample was subjected to the oscillatory sinusoidal strain e0 < 25μe. Studies carried out at a specific temperature set-points: - 7°C, 5°C, 13°C, 25°C and 40°C and at the frequency 0.1 Hz, 0.3 Hz, 1 Hz, 3 Hz, 10 Hz and 20 Hz. The obtained results allow to conclude that the use of an inactive filler can reduce the stiffness of an appropriate designed mixes of the cold recycled foundation. In addition, the analysis of the relation E'-E'' showed a similar behaviour of a recycled base, regardless of the amount of inactive fillers in the mix composition, at high temperatures/high frequency of induced load.