GLASGRID (REGISTERED TRADEMARK) PAVEMENT REINFORCEMENT: PRODUCT EVALUATION

This project was initiated in 1989 to evaluate the performance of GlasGrid (Registered Trademark), a glass fiber mesh pavement reinforcement geotextile, in prohibiting or controlling the incidence of reflective cracking. In the summer of 1990, test sections examining two different types of the product, a single strand grid and a double strand grid, were constructed on STH 57 in Sheboygan County. After the existing joints and cracks of the portland cement concrete (PCC) pavement, originally constructed in 1957, were cleaned and repaired, the project was overlaid with a 1 1/2-in. lift of asphaltic concrete. The GlasGrid was then installed in the test sections in 5-ft widths across the transverse joints and cracks of the underlying jointed PCC pavement. With the GlasGrid reinforcement in place, the final 1 1/2-in. layer of the 3-in. asphaltic concrete overlay was placed over the entire project length. Within six months, reflective cracks were already appearing in the test sections. By the end of the fourth year, the percentage of reflective cracking occurring in the double strand test sections surpassed that of the control sections, which had no GlasGrid. The reflective cracks in the GlasGrid test sections were mainly Type 3 (banded) cracks. The reflective cracks in the control section were Type 1 (less than 1/2 in. in width) cracks only, a much less severe crack than Type 3. Annual crack surveys were completed at the test site during the first five years and after ten years. A final field review was completed in April of 2002. The results of these surveys showed that both the single strand grid and double strand grid variations of the GlasGrid product performed unsatisfactorily and were unable to prohibit or control reflective cracking effectively. The Wisconsin Department of Transportation does not recommend the use of GlasGrid pavement reinforcement in any future overlay projects.