New Polish catalogue of typical flexible and semi-rigid pavements

The paper covers the following topics important for the development of the new Polish Catalogue of typical flexible and semi-rigid pavements: reasons for preparing the new issue of the Catalogue of typical flexible and semi-rigid pavements, items introduced in the new issue, organise the terminology related to pavements, design traffic calculations and new equivalent axle load factors, new materials and technologies included in the Catalogue, classification of subgrades based on the soil material and drainage conditions, designing of lower layers and improved subgrade, designing of the main, upper layers.

The stress and strain calculations in the pavement were carried out according to the theory of elastic layered half-space.An assumption that a single axis transmits the load through two single wheels, represented by circular contact area of P=50 kN load and q=850 kPa tyrepavement contact pressure was assumed in the calculations as appropriate for contemporary heavy goods vehicles.
The design criteria used for flexible pavement design were: bottom-up fatigue cracking of asphalt layers, according to the latest AASHTO M-ENPDM method of 2004 (see equations 2 and 3) [11] and permanent deformation according to the Asphalt Institute method of 1982 [10] The number of load applications until the development of fatigue cracking in asphalt layers was calculated with the following equation: where: -Nf -number of load repetitions until the development of fatigue cracking on 50% of the overall surface area of traffic lane, -݇ ଵ ᇱ -calibration constant depending on the asphalt layer thickness and type of fatigue cracking, -εt -tensile strain at the critical point in the vertical cross-section of pavement, -, -E -stiffness modulus of asphalt layer, MPa, -C -coefficient depending on the volumetric parameters of asphalt mixture calculated as ‫ܥ‬ = ‫,ܯ01‬ in which M is calculated as follows:

23 1 .Fig. 1 .4
Fig. 1.Schematic diagram and terms relating to courses of flexible and semi-rigid pavement structures and improved subgrade.

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N100 -design traffic being the cumulative number of equivalent standard axles of 100 kN per traffic lane during the design life, -NC, NC+P, NA -cumulative number of HGVs without trailers (C), HGVs with trailers or semitrailers (C+P) and coaches and buses (A) during the design life, -rC, rC+P, rA -load equivalency factors (LEF) to convert the numbers of HGVs without trailers (C), HGVs with trailers (C+P) and coaches (A) to the number of 100 kN ESAL, -f1 -load distribution factor of design lane, f2 -lane-width factor, f3 -longitudinal gradient factor.In the new issue of the Catalogue the load equivalency factors ‫ݎ‬ , ‫ݎ‬ ା , ‫ݎ‬ were determined on the basis of the available weigh-in-motion data.Weighing in motion (WIM) is a continuous process, providing complete data on heavy traffic, including vehicle type identification, axle loads, axle configuration, vehicle dimensions and speed.The pavement loading investigation was carried out using the measurement data obtained from weighing of over 4.2 million HGVs.The analysis of traffic included a determination of axle load and gross weight distributions, distribution by vehicle type, annual, weekly and daily traffic load distributions and the percentage of overloaded vehicles [1,2].The most important element of the research was evaluation of the severity of vehicle influence on the pavement structure, represented by the load equivalency factors.Their values were calculated for each recorded vehicle using the following methods: AASHTO [3], fourth power law, French method [4] and method developed at the Gdańsk University of Technology [5].Parameters determining the severity of the vehicle's action on pavement structure, appropriate to the method were taken into account, including: axle spacing (relevant to tandem and tridem axles), type of pavement (flexible or semi-rigid) and thickness of pavement courses and finally tyrepavement contact stresses.The final values of load equivalency factors for vehicle classes were determined through static analysis of the load equivalency factors of individual vehicles, taking into account weight and axle load variations depending on the maximum legal load and class of road.Some safety margin was added to account for different load DOI: 10.1051/ , 04002 (2017) 71220 1 MATEC Web of Conferences matecconf/201 22 GAMBIT 2016 4002 application parameters on different roads, possible vehicle overloading, future increase in gross weights and axle loads of vehicles as well as the dynamic effects.

5Fig. 2 .
Fig. 2. Some typical arrangements (types 1-4) for traffic categories KR5-7 and G4 bearing capacity class of subgrade (PP -sub-base, WM -capping layer, WUP -improved subgrade layer) The new issue of the Catalogue specifies thicker solutions as compared to the 1997 issue which, however, are in compliance with those currently used in other countries.
Vb -effective content of bitumen, % v/v, -Va -air voids content, % v/v.The AASHTO 2004 criterion represented by equations (2) and (3) is based on the number of load repetitions until the development of fatigue cracking on 50% of the overall surface area of the traffic lane.However, by rearranging the above equations it is possible to calculate the number of load applications for any level of development of fatigue cracks.The following cracking severity levels were adopted for the purpose of the performed analyses: 10-20% for pavements with unbound base and 5-10% for full-depth asphalt pavements.According to the conduced calculations and analyses all thicknesses of the upper pavement courses are sufficient to fully cover the load ranges in the respective traffic classes of roads.In comparison to the Catalogue issue of 1997 the new issue of 2014 provides more typical options for the design of upper courses in pavement structures with unbound base.What is completely new are typical pavement structures with cold recycled base and the use of porous asphalt in bituminous courses.The thicknesses of the upper courses of typical pavement structures are presented in Table 2.