Wojciech Bańkowski

Reasons of premature cracking pavement deterioration: a case study

Cracking deterioration was observed on a motorway after only few years after construction. The motorway pavement was semi-rigid with a relatively thin thickness: 4 cm wearing layer, 11 cm asphalt base course, 20 cm lean concrete base course, 20 cm cement stabilized base course, 20 cm drainage layer, subgrade. lean concrete base course was cut in spacing 2,5 m to reduce the reflective cracking in asphalt layers. Testing program included: coring and materials composition testing, FWD testing to evaluate pavement layers stiffness modulus, radar testing to measure layer thickness, and to detect water presence in pavement layers, evaluation of cracks type and spacing, interlayer bond testing, low temperature resistance of asphalt wearing course. Testing results led to following conclusions: extremely low winter temperature in combination with relatively thin pavements thickness and semi-rigid pavement type was the reason of transverse cracking, longitudinal cracking observed on one of the sections were evaluated as top-down fatigue type cracking, low interlayer bond between asphalt base layers was one of the main reason of lower fatigue resistance of the pavement, lack of drainage in motorway median caused the presence of water in the pavement layers, and increased the danger of premature pavement deterioration, unpredicted increase in road traffic caused longitudinal top-down fatigue cracking.

Asphalt Pavement Design using Results of Laboratory Fatigue Tests of Asphalt Mixtures

ABSTRACT Fatigue tests with use of 4 Point Bending test were performed on conventional and innovative asphalt mixtures: typical asphalt concrete, high stiffness modulus asphalt concrete and stone mastic asphalt with conventional and special binders, multigrade or elastomer-bitumen. The results of fatigue testing were applied for development of fatigue characteristics of particular asphalt mixtures. Pavement design analysis was performed with design of thickness of asphalt layers and prediction of their fatigue life. It was shown that use of fatigue law developed from laboratory test results for asphalt mixture enabled to prove the efficiency of use of innovative materials. It is possible to reduce total thickness of asphalt layers when applying in base course high stiffness modulus asphalt with special binders without decrease in fatigue life.