Article

Calculation of the equivalent temperature of pavement structures

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Abstract

Due to the di culties of the description of temperature varia- tion, rating of asphalt pavement structures respecting fatigue is made on equivalent temperature. In general, equivalent temper- ature is calculated according to average and weighted air tem- perature. It is proven, based on processing numerous data pro- vided by the temperature detectors laid in the pavement struc- tures as well as determination of the partial fatigue values, which the present method used to calculate the equivalent tem- perature results in data losses. Furthermore, it is proven, that pavement structure temperature based on air temperature can be determined only to limited extent. Knowledge of temperature distribution of the pavement structure provides the possibility of more accurate design.

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... The internal resolution of the temperature sensors were 0.0625 °C and the accuracy of the output was 0.1 °C. Over a period of one year this provided 52,560 data point for each depth, which is considered fairly detailed characterisation of a pavement structure [14]. ...
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The French pavement design method provides a very comprehensive, probability-based design approach. It also provides a fairly sophisticated method for establishing the equivalent pavement temperature, which has been used worldwide for different applications. The objective was to analyse the applicability of the French method for calculating the equivalent pavement temperature for Hungarian climatic conditions. It considers the thickness of the pavement structure and facilitate pavement temperature distribution. It was found that the French method provides a comprehensive approach and can facilitate variable climatic conditions and pavement temperature distribution while considering the thickness of the pavement structure. This provides fit for purpose solutions and eliminates the overly simplified approach to use a single equivalent pavement temperature for variable climatic and pavement conditions. Real pavement temperature data provided crucial input into the accuracy of the methodology. Asphalt modulus values and asphalt fatigue properties at different temperatures were estimated using an internationally well accepted method. The next focus item of this research work will be to refine the calculations based on asphalt modulus master-curves and fatigue data collected from laboratory testing at different temperatures.
... Due to temperature dependence, determination of the residual service life value of a multi-layered pavement model would require a long and complicated series of calculations because of the different values of asphalt modulus. Instead, the present method -utilizing the Miner's hypothesis -uses equivalent temperatures and asphalt modulus values for each layer, which, if they remain unchanged throughout the whole year, would result in the same fatigue damage in the pavements as the combined effect of the strains of the different asphalt moduli of different temperatures (Fi & Pethő, 2008;Pethő, 2008). ...
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... fárasztó hatása alapján. Az ekvivalens hőmérséklet Teq értéke tekintetében hazai adatokra alapozva Fi és Pethő 17,7°C-ot javasolt[79]. Később Pethő a hazai típus-pályaszerkezetek hőmérsékleti profiljainak és fáradási ellenállásának elemzésével arra jutott, hogy gyakorlati szempontból megfelelő a jelenlegi előírás szerinti, 20°C-os érték használata[7]. Ennek megfelelően jelen kutatásban vizsgált méretezés során a kiválasztott referencia-hőmérséklet Tref=Teq=20°C.főbb modellek jellemzően a merevségi modulus egy adott referencia-hőmérsékletre való korrekciójára vonatkoznak, illetve ritkábban, általánosan adnak meg hőmérséklet-merevség összefüggést. ...
... The equivalent temperature is calculated considering various pavement temperature-traffic combinations, according to Miner's cumulative damage law. For its value, Fi and Pethő found 17.7°C based on Hungarian data [16]. Later Pethő extended the original research with the analysis of the temperature profile of the structures given in the Hungarian pavement catalogue, and stated that the use of 20°C as equivalent temperature, as according to the current standard, is adequate for design purposes [2]. ...
Article
The paper addresses the determination of a stiffness-temperature correction model for the use in a mechanistic overlay design method, developed at the Department of Highway and Railway Engineering, Budapest University of Technology and Economics. Eleven models are selected and evaluated based on 215 laboratory stiffness test results at various temperatures of 47 different AC22 binder course type mixes. As the results showed, for the rough temperature correction of Hungarian binder course mixes for the use in the proposed design method; the model used by the AASHTO 1993 pavement design method is most accurate based on the standard error of the estimate of the selected models.
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Article
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the trade-off regarding stiffness and low-temperature behaviour of hot mix asphalt (HmA) mixes is well known – the higher the stiffness of an asphalt mix is, the lower its relaxation during fast cooling down in winter, resulting in thermal cracking at higher winter temperatures. the accumulated tensile stress together with the stress deriving from heavy traffic load leads to severe transverse cracking of the pavement. the German company j. rettenmaier & söhne has developed several fibre based pellet additives in its research laboratories in Germany. the most commonly used pellet product is used for stone mastic asphalt mixes to prevent the binder drain-down from the surface of the aggregates. An innovation of the company presented in 2014-2015 was a new type of additive named viAtoP®plus FeP (Functional Elastomer Pellet), consisting of approx. 20% special cellulose fibre and 80% elastometric additive. this new type of pellet is designed for HmA wearing courses of heavy duty roads, improving pavement performance through superior binder properties. viAtoP® plus FeP is probably a competitive of common modified binders regarding performance versus price and simplicity in its application. it is expected to improve stiffness of the mix while somewhat improving low temperature behaviour as well.As there is little chance of the selected modifications to decrease fatigue life, it is assumed to be at least adequate in all cases and no need to be analysed. Low and high temperature behaviour, however, is a challenge to all modifications. in our research stiffness and low-temperature behaviour of three asphalt mixes were tested and compared: one with polymer modified bitumen and one with the new additive, together with a standard mix used for reference. Plastic deformation at high temperature is tested according to en 12697-22 using small wheel tracker, low temperature cracking is tested using equipment developed at the laboratory of the BmeDepartment of Highway and railway engineering, according to en 12697-46 Thermal Stress Restrained Specimen Test (tsrst) method, and stiffness using test method c of en 12697-26, Indirect Tensile strain on Cylindrical Specimen (it-cy). stiffness was measured at different temperatures to obtain a more comprehensive picture of the mixes. to make the research more interesting the chosen mix contains approx. 10% reclaimed asphalt according to endeavours of sustainability in the asphalt industry. Based on the results, the manufacturer’s estimations on mix performance and some prior tests made in Germany an evaluation was made on a mix commonly used in Hungary. the benefits of the selected modifications were compared to each other and the results are presented and evaluated.keywords: Hot mix Asphalt, viAtoP® Plus FeP, additives, stiffness, low temperature behaviour, asphalt mix modification. The effect of VIATOP plus FEP on the stiffness and low temperature behaviour of hot mix asphalts. Available from: https://www.researchgate.net/publication/282589138_The_effect_of_VIATOP_plus_FEP_on_the_stiffness_and_low_temperature_behaviour_of_hot_mix_asphalts [accessed Feb 19, 2016].
... The equivalent temperature is determined by applying Miner's law. Accodding to the Shell procedure [2,3] the equivalent temperature can be also called as "effective temperature". The effective stress generated in the pavement structure characterized by a single temperature model corresponds to the stresses calculated on the basis of models set up in accordance with various temperature values. ...
Conference Paper
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The paper presents implementation of equivalent temperature for design of airport asphalt pavements. The calculation methods of equivalent temperature: the Shell method, the French method and method that use the Asphalt Institute fatique criteria were presented. An example of calculations of equivalent temperature for Gdansk Airport was introduced and discussed. It was shown that methods of calculation of equivalent temperature that are usually used in the design process of road pavements can be also implemented with success in design process of airport pavements.
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The paper presents application of equivalent temperature for design of asphalt pavements. The calculation methods of equivalent temperature: the Shell method, the French method, the methods that use the AASHTO and the Asphalt Institute fatigue criteria were presented. The results of calculations of equivalent temperature for Polish climatic conditions were presented and discussed. It was shown that different asphalt pavement design methods and utilization of Polish climatic data resulted in various calculated values of equivalent temperature that could be used in the design process.
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The concept of ecologically conscious and energy saving roads must be expanded to the performance of the asphalt mixtures as well as to the test related to it. This paper investigates the tests focusing on a better description of the behaviour of asphalts as well as on a deeper revelation of the impact of different compositions. Based on the international experiences the recording of the asphalt's complex module over the entire temperature range by the determination and evaluation of the mater-curves appeared as a possible solution for more precise description of the asphalt behaviour.
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Asphalt Pavement Design
  • Aim Claessen
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