Appropriate skid resistance properties of airfield pavements are extremely important in terms of the safety of air operations. When discussing skid resistance properties of airfield pavements, we should not limit the subject only to the friction coefficient, which determines the state of its roughness. Attention should be paid to the fact that a significant component of friction characteristics of a tyre/pavement contact surface is the pavement texture (microtexture and macrotexture). The authors of the article presented the currently applied study methods in the scope of evaluating the texture of road and airfield pavements. The paper also presents sample results of field tests, which were conducted on new airfield pavements (executed in the cement concrete and asphalt concrete technology), as well as their short analysis in relation to evaluating the skid resistance properties (friction coefficient). Particular attention was paid to the current requirements in this scope, imposed on airfield pavements and the assessment criteria of the obtained results. Moreover, the paper also presents a direction of further works conducted by the authors with a broader team, in the scope of developing the study method for the assessment of airfield pavement texture.
The contact surface of the wheel with the airport surface is important for the safety of flight operations in the ground manoeuvring area. The area of the contact surface, its shape and stress distribution at the pavement surface are the subject of many scientists’ considerations. However, there are only a few research studies which include pressure and vertical load directly and its influence on tire-pavement contact area. There are no research studies which take into account aircraft tires. This work is a piece of an extensive research project which aims to develop a device and a method for continuous measurement of the natural airport pavement’s load capacity. One of the work elements was to estimate the relationship between wheel pressure and wheel pressure on the surface, and the area of the contact surface. The results of the research are presented in this article. Global experience in this field is cited at the beginning of the article. Then, the theoretical basis for calculating the wheel with the road surface contact area was presented. Next, the author’s research views and measurement method are presented. Finally, the obtained test results and comments are shown. The tests were carried out for four types of tires. Two of them were airplane tires from the PZL M28 Skytruck/Bryza and Sukhoi Su-22 aircraft. Two more came from the airport ASFT (airport surface friction tester) friction tester-one smooth ASTM; the other smooth retreaded type T520. The tires were tested in a pressure range from 200 to 800 kPa. The range of vertical wheel load on the pavement was 3.23–25.93 kN for airplane tires, and 0.8–4.0 kN for friction tester tires. The tests proved a significant influence of the wheel pressure value and wheel pressure on the surface on the obtained contact surface area of the wheel with the surface. In addition, it was noted that the final shape and size of the contact surface is affected by factors other than wheel pressure, tire pressure and dimensions.
The assessment of the anti-skid properties of airfield pavements is one of the elements in the process of determining their current technical condition, which is important in terms of the safety of air operations. The condition of the pavement should be qualified on the basis of the specified and required values (criteria), in this case, the coefficient of friction and the depth of the texture. Unfortunately, in practice, the assessment of the texture of new airfield pavements raises some doubts with regard to the existing requirements. The work presents an analysis of the results of texture tests for new airfield pavements in relation to current requirements. In addition, the authors proposed a new criterion of average texture depth for new airfield pavements, based on actual field measurement results. Field studies used an innovative method of assessing anti-skid properties with a measuring system that allows simultaneous measurement of the coefficient of friction, μ, and the new continuous coefficient of average profile depth and texture CMPTD, from which MPD (Mean Profile Depth) and ETD (Estimated Texture Depth) can be determined. The results of the tests cast doubt on the possibility of obtaining the average texture depth (currently 1.00 mm) required for new airfield pavements.
15 May 2018 in IOP Conference Series: Materials Science and Engineering
The safety of traffic, including both road and air traffic on a ground manoeuvre area, depends on many factors. These mainly include the anti-slip properties of a road or airfield pavement on which the traffic takes place. The basic pavement parameter that determines its characteristics in terms of anti-slip properties is the skid resistance, which constitutes the ratio of the wheel downforce and the friction on the contact surface. There are currently many devices for continuous measurement of the skid resistance (Continuous Friction-Measuring Equipment - CFME) around the world. Most of them, in principle, do not vary much from one another. Most of the devices measure the measuring wheel's downforce on the pavement and the friction on the wheel-pavement contact surface. The skid resistance is the result of this measurement. The devices vary in many aspects, such as the type and size of the used measuring tyre, pavement-wheel slip or tyre pressure. This does not mean that the results obtained from various devices mbe directly compared. On the other hand, each device allows determining the pavement's anti-slip conditions in terms of the requirements specified for the given type of devices, thereby enabling pavement classification in these terms. The classification allows for comparing the results obtained from various measuring devices. The paper presents an overview of equipment used in Poland and around the world to measure the skid resistance on airfield pavements. The authors draw attention to the requirements for pavements in terms of their roughness, with division into road and airfield pavements.
An important factor that affects the safety of flight operations is the proper management of airports, which should be based on the obtained in systematic way information about the state of the surface of the functional elements. One of the characteristic quantities of the technical condition of airport indicator is the assessment of the degree of degradation. It should be noted that the degradation is a slow process extended in time and is the lowering of the properties of the structure by external influences, which in turn generates the changes in their structure. Rating degrade surface should be conducted periodically, which period shall be estimated on the basis of information obtained from the process of the operation of aircraft. Demotions surface is determined on the basis of the type and quantity survey found damage and made repairs. The basis for evaluating the degree of surface degradation is to obtain data from surveys conducted using the method of visual and inventory of them. Research by visual method, despite its apparent simplicity, it is difficult to implement. Qualification of damage or repairs to the appropriate group is often not clear, and therefore the inventory process is described in the documentation of quality management system. The multi-criteria analysis is a method of evaluating the weighted supporting estimating the degree of degradation airfield pavements based on data obtained through inspections performed. Its base is included in the determination of a number of criteria for the selection variant, taking into account different weights to each criterion. The value of the indicator characterizing the degree of surface degradation in relation to estimated criteria allows you to schedule the necessary resources needed to carry out repairs and rational planning of repairs.
Airfield infrastructure management should be effective. First of all, renovation works should be planned and carried out so that the equipment or resources, both financial and personal, are used optimally. The basis for planning funds should be knowledge about the actual pavement condition and, more importantly, the future pavement condition. The main goal of the paper is to present a complex method of technical condition assessment of airfield pavements made of cement and asphalt concrete, as well as natural pavements, which are part of the ground maneuvering field on each airfield. The authors propose a new method of assessing the technical condition of the pavement based on the Airfield Pavement Condition Index (APCI). Compared to existing methods, based mostly on the visual assessment of the pavement surface damages, the APCI method also includes the inventory of the repairs and diagnostic tests such as the assessment of the load capacity, evenness, anti-skid properties and the surface layer tensile bond strength. The presented mathematical models enable automation of pavement assessment process. That can lower costs and speed up whole evaluation.