Asphalt Reinforcement with Polyester Grids: Practical Experience in Airfields
Construction of asphalt overlays is a conventional method used for rehabilitation of airfield pavements. However, cracks in an existing flexible or rigid pavement, and/or construction joints in the existing rigid pavement can rapidly propagate into new asphalt overlay as a result of the aircraft loading combined with temperature changes. Widely known as reflective cracking, this phenomenon can be addressed by incorporating polyester (PET) asphalt reinforcing grids that have shown significant results in delaying the process of crack propagation. The reinforcement occurs through a mechanism whereby the polymer grid captures the peak stresses at the tip of the crack, distributes them over a larger area and therefore achieves a retardation of the crack propagation into the newly constructed asphalt overlay. Utilizing basic theory and practical experiences, this paper will demonstrate the success and extended pavement life that can be achieved by using polyester asphalt reinforcing technology in airfield pavements. Evaluation of long-term performance on site and the key factors associated with the effectiveness of the reinforcing material (e.g. the loss of tensile strength due to the paving procedure, and the importance of the bond-strength) have been highlighted in particular. Furthermore, based on 40 years’ practical experience with asphalt reinforcement, this paper presents typical applications and also limitations associated with the use of asphalt reinforcement in rehabilitation of deteriorated runways, taxiways and aprons at airports. The paper concludes that the extended pavement life achieved by the use of this technology reduces both the construction disruption to airfield operations and the associated maintenance costs to asset owners.
The presented laboratory tests as well as case studies have shown that asphalt reinforcement grid made from high modulus polyester can be a highly effective solution against reflective cracking in asphalt overlays.
The paper has demonstrated that, in addition to a good interface adhesion (interlayer bond), polyester’s high resistance against both installation damage and fatigue under dynamic loads is a key factor for successful stress distribution and effective crack retardation.
Based on the observed performance under site and laboratory conditions, it can be concluded that the service life of the rehabilitated pavement can be extended considerably by using a high modulus polyester asphalt reinforcing grid. As a result, significant advantages in reducing maintenance costs as well as construction disruption to airfield operations can also be achieved.