Pavement Fatigue Degradation Phenomenon Assessment Based on Multi-load FWD Data and Stochastic Process Evaluation

Abstract

IntroductionThe pavement engineering and related technologies must mainly take into account the influence of multiple sources: extreme temperatures, time-related variable properties of the used materials, snow, rain, the properties of pavement subgrade, traffic load, and maintenance policy. These issues were discussed very systematically in the paper [24] and although its contents refer to the pavements localized in the areas with the cool climate, many of the elements included there can be applied to any type of pavement and varied climatic zones. In any case, these are just some factors that demonstrate the range of the pavement degradation phenomenon and, above all, their stochastic nature. The most complex observations of pavement degradation in time domain are probably ensured by the measurements results analysis of pavement sections in natural conditions. Among them, the most relevant are those that relate to the full-scale accelerated pavement testing [2,20]. The paper [10], on the basis of pavement deflection measurements values tested both in singleload and multilevel-load tests in the range from 17 kN to 70 kN, describes a method of prediction of the rutting depth. There were confirmed a satisfactory compatibility between these quantities for a wide range of road pavement structures. It is worth noting here that it might provide a basis for the development of small-scale accelerated pavement testing approach. The accelerated test series, using the FWD-type unit, were also initiated during the preparation of the report [4]. It was noticed there that the deflection ratio obtained from multi-load level deflections may predict the type and quality of the base/subgrade materials. At the same time, the true hypothesis says that the difference in the multi-load deflections small yield information related to the future performance of pavements. The characteristic feature of construction materials fatigue phenomenon assessment is their randomness [17]. At the basis of the description of cyclic phenomena (fatigue phenomena) lies the theory of cracks initiation. And the most appropriate mathematical description of the fatigue phenomenon are the theories of stochastic processes [17]. The microscopic initiation of cracks in the pavement layers bonded with any binder is subject to considerable uncertainty, both in relation to the speed of the cracks development and its

Effect of Strengthening on the Fatigue Life of Construction Materials

“…As in the previous example the updated static strength is expressed by Eq. (8). The coefficients used in the model were obtained from the literature [4,10].…”

“…Therefore, several hypotheses aiming to estimate the fatigue life of the structure under variable loads have been posited, including modified Miner's rule (MMR) and relative Miner's rule (RMR). The phenomenon of fatigue is described more and more accurately, for example, by the description as a stochastic process [8,9,10]. High accuracy may be obtained by taking into account the strengthening effect of load cycles below the fatigue limit (LALS).…”