As any other construction structure and material, asphalt linings are subject to natural ageing. Although the majority of asphalt membranes still fulfill their function after 30 or more years of operation, one must consider their reconditioning and maintenance. This is especially the case for surfaces subjected to significant loadings and with increasing age.
Large and rapid changes of water load in combination with extreme changes in temperatures lead to tension which cannot any longer be completely compensated by the embrittled material. These factors, as well as inferior paving equipment and lining systems deployed, now result in the reconditioning of projects from the 1950’s and 1960’s. The old lining design of two superimposed impermeable layers now requires reconstruction measures. Typical signs are blisters and an imperfect connection between the two layers as well as cracking.
• Removal of the complete drainage and dense lining system and re-construction.
• Removal of the dense layer and replacement by a new dense course.
• Partial removal / milling of the surface of the dense layer.
• Partial rehabilitation of stressed areas – for example for changing water levels – or local damaged spots.
A prerequisite to any rehabilitation works is to carry out an intensive laboratory investigation of the old asphalt concrete layers. The results obtained from such investigations, combined with the existing construction design, will determine the type of rehabilitation needed.
Important aspects of any investigations are the following: taking and analyzing samples from the old layers, visually inspecting the existing construction, documenting the failed areas, checking leakage reports and studying old as-built documents.
Experience over the years has shown that bituminous lining in basal areas or areas which are permanently under water rarely show any signs of ageing.
In many cases, only parts of the top layer of the sealing system has to be replaced. In addition, it is possible to transform the existing lining into a controlled lining system. The old dense layer will serve as a lower impermeable membrane and will be overlaid by a drainage layer and a dense concrete layer.
Our expert engineers can offer extensive support in the planning and evaluation of the most cost-efficient and sustainable rehabilitation methods needed for your project.
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