Józef Judycki

Durability of Asphalt Concrete Subjected to Deteriorating Effects of Water and Frost

AbstractThe paper presents testing of the detrimental effects of water and frost on asphalt pavements. It included laboratory testing of fatigue life of asphalt concrete that was subjected to action of water and frost and field testing of damages caused by water and frost on existing asphalt pavements, such as stripping, raveling, and potholes. Laboratory simulation of water and frost action was based on the original AASHTO T283 method and its modification. The original method was modified in such a way that instead of a single freeze-thaw cycle, 50 and 150 cycles were applied. Fatigue life was measured in the indirect tensile fatigue test in the Nottingham Asphalt Tester (NAT) apparatus. The asphalt concrete specimens were prepared in laboratory. Some specimens contained liquid adhesive agent—namely, fatty amine—and others did not. The detrimental effect of water and frost was clearly identified. Also, the results of field investigation—condition survey of existing pavements and the results of laboratory...

Analysis of effect of overloaded vehicles on fatigue life of flexible pavements based on weigh in motion (WIM) data

Overloaded vehicles have a significant impact on pavement fatigue life and distress. As the studies show, the phenomena intensify when the control of traffic is poor. The paper presents the results of the research including analysis of weigh in motion data from eight stations and analysis of asphalt pavement fatigue caused by mixed traffic. Distributions of vehicles axles load including the multiple axles effects are presented. Mixed axle loads were transformed into equivalent number of standard 100 kN axle loads. The regression model of load equivalency factor depending on the axle load distribution and the percentage of overloaded vehicles is presented. The analysis of the effect of overloaded vehicles on decrease of fatigue life of a pavement structure is presented. The analysis has shown that the increase of percentage of overloaded vehicles from 0% to 20% can reduce the fatigue life of asphalt pavement upto 50%.

Verification of the Criteria for Evaluation of Water and Frost Resistance of Asphalt Concrete

ABSTRACT The paper presents the results of field investigation—condition survey of existing pavements and the results of laboratory tests on water and frost resistance of samples cored from the these pavements. The purpose of testing was to verify the criteria for evaluation of the resistance of asphalt concrete to the action of water and frost by way of comparing the results of field and laboratory tests, followed by evaluation of their reliability. The results of field and laboratory tests were subjected to comparative analyses. The output of these analyses includes conclusions and recommendations.

Investigation of low-temperature cracking in newly constructed high-modulus asphalt concrete base course of a motorway pavement

The paper presents the issue of low-temperature transverse cracks which have developed in newly constructed base courses made of high-modulus asphalt concrete mix (HMAC). Numerous transverse cracks developed in the analysed HMAC base during the winter season before the pavement was actually completed, both at the transverse joint locations and in the areas between them. This had not happened so far on such a scale during road construction projects in Poland. The research included both field examination and laboratory testing of high-modulus asphalt concrete used for construction of the base course of the A1 motorway pavement, followed by computational analysis to investigate the causes and mechanism of the analysed pavement distress. The first part of this paper describes the pavement structure, gives the main requirements applicable to HMAC, and presents the results of the cracking survey, visual assessment and laboratory tests carried out on cores cut from the analysed pavement. Later in the article, the causes of cracking are analysed, taking into account the temperature of air and pavement, performance grade assessment of the bitumen used in the works, homogeneity of the constructed layer and calculated thermal stresses induced in HMAC layers. The examinations and analyses allowed to conclude that the main causes of cracking included too stiff mix, taking into account the climate of Poland, deviations from the pre-defined installation practice during the construction of the base course and leaving the HMAC surface unprotected by the overlying layers: binder and wearing courses during winter. Finally, compliance with the best construction practice during placement of HMAC mixes and use of softer or polymer-modified bitumens are indicated as being critical to avoiding distress of HMAC pavement courses.

Determination of Equivalent Axle Load Factors on the Basis of Fatigue Criteria for Flexible and Semi-Rigid Pavements

ABSTRACT This paper presents the analysis of equivalent axle load factors on the basis of fatigue criteria used in various mechanistic-empirical methods of pavement design. It specifies the formulas of fatigue criteria for flexible pavements (asphalt fatigue cracking and structural deformation criteria) and for for semi-rigid pavements (fatigue cracking criteria for cement treated bases—CTB). These criteria were used to derive the formulas to calculate the equivalent axle load factors. The numerical results of calculation are given. It was found that equivalency factors are closely related to the mathematical form of fatigue criteria. The formulas for calculating the equivalent axle load factors for flexible pavements resemble the well known “fourth power equation”, except that the exponent n ranges from 3.3 to 5.0 in relation to the fatigue criteria used. The formulas for semi-rigid pavements are much more complex. The equivalent axle load factors differ in relation to pavement structure and depend on bending strength or limit strains of cement treated base and on configuration of semi-rigid pavement (thicknesses and material of layers and subgrade and their moduli). There are considerable differences between the equivalent axle load factors derived for semi-rigid pavements from different fatigue criteria used in various design methods. If an exponential formula, similar in form to the “fourth power equation”, was used the exponent n derived from various design method ranged from 4 to 20 and even more. The formulas were derived assuming linear relationships between stresses and strains induced in layers of pavement structure and the axle load value. This assumption has been verified for certain pavement structures.

Influence of selected WMA additives on viscoelastic behaviour of asphalt mixes and pavements

Abstract Warm mix asphalt additives are effective in decreasing production, laying and compaction temperatures of asphalt mixes. However, there are still questions concerning influence of warm mix additives on properties of asphalt mixes and pavement performance. This paper presents results of the comprehensive research of viscoelastic behaviour of asphalt mixes and pavement structures with layers made with warm mix asphalt additives at high temperatures. Two additives of significantly different effects on mixes at higher temperatures were selected for analysis, namely aliphatic synthetic wax produced with the use of Fisher–Tropsch method and formulation of surfactant- based molecules (ionic and non-ionic). Viscoelastic properties of mixes with these two additives and, as a reference mix, with neat unmodified asphalt binder were determined in uniaxial compression with sinusoidal loading using Asphalt Mixture Performance Test. The viscoelastic analysis of pavement structures was performed with use of the VEROAD software and data from laboratory testing. Two different pavement structures were analysed, for light and heavy traffic. The temperature distribution in pavement structure during the hottest summer day in northern Poland in 2012 was taken into account. The model of pavement was loaded with moving wheel at different speeds. The analysis has shown that two tested warm mix additives had different effect on viscoelastic transient response at high temperatures. One of them (Fischer–Tropsch wax) evidently caused an increase in resistance of asphalt mix and pavement structure to loading at high temperature. The second additive (formulation of surfactant-based molecules) slightly reduced resistance of asphalt mix and pavement to loading at high temperatures as compared with the reference mix.

Evaluation of Thermal Stresses in Asphalt Layers Incomparison with TSRST Test Results

The paper presents the results of calculations and laboratory determination of thermal stressesat low temperatures. The modified Hills and Brien’s method was used to calculate the thermal stresses in asphalt layers of pavements and the results were compared againstthe values obtained at a laboratory with the Thermal Stress Restrained Specimen Test (TSRST) method. The laboratory investigations were conducted using plain grade bitumen, modified bitumen with SBS elastomer modification and multigrade type bitumen. It was found that the type of bitumen binder in asphalt concrete is of significant importance to the value of the calculated thermal stresses. For thecooling rate of 10oC/h the lowest value was obtained for asphalt concrete produced with the use of multigrade type bitumen. This fact can be an indication of a better resistance to low temperature cracking. The thermal stresses were had the highest values for asphalt concrete produced with plain bitumen. A good correlation was obtained betweenthe thermal stresses calculated withthe Hills and Brien’s procedure and the values of thermal stresses determinedwith the TSRST method.

A new viscoelastic method of calculation of low-temperature thermal stresses in asphalt layers of pavements

Abstract The paper presents a new method of calculation of thermal stresses in asphalt layers of pavements induced by cooling or heating. The method, developed by the author, is based on the analytical solution for the linear viscoelastic Burgers model extended numerically for the case of asphalt layers whose rheological parameters are strongly dependent on temperature. The coefficient of thermal expansion and Poisson’s ratio may optionally be taken either as constant or varying with temperature. Two equivalent numerical methods have been developed, named as ‘the incremental method’ and ‘the stress increase and relaxation method’. The computer program was developed for calculation of thermal stresses in several different cases of temperature impact, included constant rate cooling and heating, change of temperature and relaxation and a cycle of first cooling, relaxation and second cooling. What the most important practically, the solution for any change of temperature, modelling real winter changes in long period of time, was also developed. Several examples of calculations are presented. The results obtained with use of this method are promising and appear to be acceptable. The advantages of the new method in comparison with existing methods are that it takes fully into account the viscoelastic properties of a layer and the method is correct if the material does not meet the time–temperature superposition principle.

Verification of the new viscoelastic method of thermal stress calculation in asphalt layers of pavements

Abstract The new viscoelastic method of thermal stress calculations in asphalt layers has been developed and published recently by the author. This paper presents verification of this method. The verification is based on the comparison of the results of calculations with results of testing of thermal stresses in Thermal Stress Restrained Specimen Test. The calculations of thermal stresses according to the new method were based on rheological parameters of the Burgers model. The parameters were measured in laboratory at different low temperatures, at long time creep under constant loading. Five asphalt mixes were tested. Three of them were high modulus asphalt concretes and two conventional asphalt concretes. Specimens were prepared in exactly the same way both for rheological creep tests and for the Thermal Stress Restrained Specimen Test. The results of measured thermal stresses were compared with thermal stresses calculated from the new viscoelastic method developed by the author and in most cases a good agreement was found. For comparison, the measured stresses were compared with results of calculations according to the existing methods. The viscoelastic Monismith method failed in prediction of thermal stresses. The prediction from the quasi-elastic Hills and Brien method was underestimated, but better than from the Monismith method and worse than from the new viscoelastic method. The reasons of discrepancies were discussed.

TESTING OF PERFORMANCE PROPERTIES OF ASPHALT MIXES FOR THIN WEARING COURSES

The paper presents the results of testing of the following properties of mixes for thin asphalt wearing courses: ageing, resistance to water and frost, resistance to rutting and low temperature properties. Two types of mixes were tested: gap graded asphalt concrete and stone mastic asphalt. Four bitumens, one non-modified and three polymer modified bitumens were used. It was found that all the tested mixes were almost equally resistant to ageing, action of water and frost and rutting, with no special distinction for the type of bitumen and mix used. However, polymer modified bitumens produced mixes with better low temperature properties. For the covering abstract see ITRD E117423.