Piotr Jaskuła

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.

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.

Field investigation of low-temperature cracking and stiffness moduli on selected roads with conventional and high modulus asphalt concrete

High Modulus Asphalt Concrete (HMAC) was introduced in Poland as a one of the solutions to the problem of rutting, type of deterioration common in the 1990s. After first encouraging trials in 2002 HMAC was widely used for heavily loaded national roads and motorways. However some concerns were raised about low-temperature cracking of HMAC. This was the main reason of the studies presented in this article were started. The article presents the comparison of performance of pavements constructed in typical contract conditions with the road bases made of HMAC and conventional asphalt concrete (AC). The field investigation was focused on the number of low-temperature cracks, bearing capacity (based on FWD test) of road sections localized in coldest region of Poland. Also load transfer efficiency of selected low-temperature cracks was assessed. FWD test confirmed lower deflections of pavements with HMAC and two times higher stiffness modulus of asphalt courses in comparison to pavements constructed with conventional AC mixtures. Relation of stiffness of asphalt layers and amount of low-temperature cracks showed that the higher stiffness modulus of asphalt layers could lead to increase of the number of low-temperature cracks. FWD test results showed that the load transfer efficiency of low-temperature cracks on pavements with HMAC presents very low values, very close to lack of load transfer. It was surprising as section with HMAC road base were aged from 2 to 5 years and presented very good bearing capacity.

Evaluation of Asphalt Mixture Low-Temperature Performance in Bending Beam Creep Test

Low-temperature cracking is one of the most common road pavement distress types in Poland. While bitumen performance can be evaluated in detail using bending beam rheometer (BBR) or dynamic shear rheometer (DSR) tests, none of the normalized test methods gives a comprehensive representation of low-temperature performance of the asphalt mixtures. This article presents the Bending Beam Creep test performed at temperatures from −20 °C to +10 °C in order to evaluate the low-temperature performance of asphalt mixtures. Both validation of the method and its utilization for the assessment of eight types of wearing courses commonly used in Poland were described. The performed test indicated that the source of bitumen and its production process (and not necessarily only bitumen penetration) had a significant impact on the low-temperature performance of the asphalt mixtures, comparable to the impact of binder modification (neat, polymer-modified, highly modified) and the aggregate skeleton used in the mixture (Stone Mastic Asphalt (SMA) vs. Asphalt Concrete (AC)). Obtained Bending Beam Creep test results were compared with the BBR bitumen test. Regression analysis confirmed that performing solely bitumen tests is insufficient for comprehensive low-temperature performance analysis.

Effect of Overloaded Vehicles on Whole Life Cycle Cost of Flexible Pavements

The phenomenon of vehicle overloading—illegal exceeding of maximum legal weight of vehicles, is a serious problem both in developing and developed countries around the world. Overloaded vehicles occur less frequently in comparison to properly loaded vehicles but due to their greater potential to cause damage they significantly contribute to distress of pavement structure. As studies show, the number of overloaded vehicles increases when the control of traffic is insufficient. Weigh in Motion (WIM) systems significantly improve control level and contribute to decrease in the number of overloaded vehicles. Data delivered from WIM were used to perform statistical analysis of vehicle overloading in Poland. The average percentage of overloaded vehicles (OV) in Poland varies from 5% for roads with high enforcement level to 23% for roads where control is poor. Every weighed vehicle was considered in terms of exceeding maximum legal gross weight and maximum legal axle load. For each vehicle separately truck equivalency factors were calculated. Subsequently the relationship between average values of truck equivalency factors and percentages of overloaded vehicles was found. This relationship was used as a basis to determine the impact of overloaded vehicles on decrease in fatigue life of pavement structure (DFL) and increase factor IF, which expresses the extension of service period. It was proved that reduction of overloaded vehicles from 23 to 5% will contribute to increase in service period of pavement structures by factor 1.5. The life cycle cost analysis (LCCA) was performed for two levels of overloading OV = 23% and OV = 5%. The paper revealed that improvement of vehicle control and reduction of the percentage of overloaded vehicles from 23 to 5% will cause the reduction of whole life cost borne by road authority by 11%.

Effect of interlayer bonding quality of asphalt layers on pavement performance

The quality of interlayer bonding at the interfaces between the asphalt layers in flexible pavements affects the overall pavement performance. Lack or partial lack of interlayer bonding between asphalt layers can cause pavements premature failures such as rutting, slippage of the wearing course, cracking or simply a reduction in the calculated fatigue life of the pavement structure. This paper shows the case studies of investigation of actual or potential premature failure of newly reconstructed and constructed pavements where low quality of interlayer bonding has a dominant meaning. In situ and laboratory tests were performed and followed by analytical calculation of pavement structure where thicknesses of layers and maximum shear strengths obtained from the tests were used. During the investigation it was found out that a low quality of tack coat as well as the same aggregate gradation in the bonded asphalt mixtures were the main reasons behind the weak quality of interlayer bonding. Partial interlayer bonding has a strong influence on reduction of calculated fatigue life of pavement. The summary of the paper includes recommendations on how to avoid the low quality of interlayer bonding of asphalt layers.

The Impact of Homogeneity of High Modulus Asphalt Concrete Layer on Low-Temperature Cracking

During winter season of 2012 numerous transverse cracks developed in high-modulus asphalt concrete (HMAC) base of newly constructed motorway. Pavement cracked both in transverse joint locations and in the area between them. Research which was conducted during investigation of the causes and mechanisms of cracking consisted of: field examination, laboratory testing of specimens cored out of the existing pavement, computational analyses and effect of pavement homogeneity on transverse crack frequency. This paper focuses mainly on impact of homogeneity of asphalt layer on number of transverse cracks. The field investigation of analyzed motorway section includes visual assessment of homogeneity and number of cracks. Laboratory test conducted on specimen cored out of the pavement allowed to assess volumetric properties: binder content, voids content and compaction degree, and mechanical properties: indirect tensile stiffness modulus and strength. Analyses of HMAC layer properties revealed their impact on the number of transverse low-temperature cracks observed in field. It was found that a less effective compaction contributes to increase in the number of cracks. Quality and homogeneity of pavement courses have a considerable effect on mechanical properties of HMAC. As analysis showed, intensity of cracks is well correlated with mechanical properties and homogeneity of asphalt layer.