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Concrete Pavement Rehabilitation by Using a High Modulus Polyester Grid as Asphalt Reinforcement

Resumo

Rehabilitation of cracked concrete pavements is usually associated with high costs and complex repair techniques. A conventional resurfacing by installing a simple asphalt wearing course over the old concrete slabs is often not an effective solution, as the expansion joints can rapid propagate to the top of the new overlay. In order to delay the development of the reflective cracks, an asphalt reinforcement grid can be placed before the resurfacing. The reinforcement adopts the peak stresses at the crack tip, distributes them over a larger area and thus retards the crack propagation. The purpose of this paper is to report the positive performance of a concrete pavement rehabilitation in the southeast of Brazil by using a high modulus polyester grid as asphalt reinforcement. The high-traffic highway MG-424 was severely cracked and damaged after an unsuccessful asphalt resurfacing. In order to evaluate the pavement support conditions and to adopt a proper rehabilitation structure, a displacement measurement device called Crack Activity Meter was used. The vertical and horizontal movements between the expansion joints and large cracks were measured and analyzed in terms of Load Transfer Efficiency. Based on the deflection results and on the observed performance, it is possible to conclude that the asphalt reinforcement is an effective treatment against reflective cracking in asphalt overlays, contributing to an extension of pavement service life.

Conclusão

Reflective cracking occurs in concrete pavements rehabilitated with a simple asphalt overlay. To delay the development of reflective cracks, an asphalt reinforcement grid can be placed before the new asphalt wearing course. High tenacity polyester as a raw material is often chosen because of the high compatibility of its mechanical behaviour to the modulus of asphalt and its good behavior under dynamic loads. The presented case study has showed that the use of an asphalt reinforcement in concrete pavement rehabilitation can be advantageous. The use of a polyester grid has to date prevented the propagation of expansion joints and cracks through the new asphalt overlay in a high-traffic highway. However, before choosing the appropriate repair solution, it is important to know the structural conditions of the existing pavement, if there are signs of pumping, excessive vertical movements or weak subgrade, for example. In the presented case study, vertical and horizontal relative movements were measured, so that the subgrade support condition and the slabs stability could be estimated. Based on the observed performance, it is possible to conclude that the asphalt reinforcement is an effective treatment against reflective cracking in asphalt overlays, resulting in an extension of the service life of a rehabilitated concrete pavement.