The Strata® Reflective Crack Relief System is an innovative approach to delaying reflective cracking and protecting the pavement structure while speeding construction to provide a smooth riding surface that extends paving dollars.
A specially engineered system to delay reflective cracking
The Strata system consists of a highly elastic, impermeable hot mix interlayer and the recommendation for polymer modified HMA overlay. The interlayer is composed of a premium polymer modified asphalt binder at a high asphalt content in a dense fine aggregate mixture. Based on a performance-based specification, the mix is designed and certified using the Flexural Beam Fatigue (AASHTO TP-321) test. The overlay recommendation is based on the compatibility with the interlayer as well as the demands of local traffic. Both lifts are manufactured and placed using standard hot mix asphalt procedures and equipment.
The Strata system delays cracks from reflecting through hot mix asphalt overlays placed on distressed Portland cement concrete pavements. The interlayer protects the pavement from moisture coming through those cracks that do form in the overlay. Further, the composition of the polymer modified asphalt hot mix materials prevents raveling and further deterioration of those cracks that do appear. The result is a protected, smooth highway surface.
The Strata system includes site selection guidelines, mix design for the interlayer, recommendation for the overlay, and SemMaterials' technical service.
Advantages of Strata Reflective Crack Relief System
- Delays 1st appearance of reflective cracking approximately 2 years
- Delays complete reflective cracking 3-5 yrs longer than fabric & HMA overlays
- Lengthens service life a projected 5 years
- Protects pavement from moisture damage (impermeable)
- Uses standard HMA production & laydown practices
- Can be recycled
The Strata System is designed for use on structurally sound but cracked Portland cement concrete pavements. Jointed pavements should have doweled joints in good condition, and any severely distressed areas should be repaired.
Local Materials with Innovative Design
SemMaterials technologists use innovative design and test methods to provide a specially engineered mixture made with our Stylink® polymer modified asphalt. Strata aggregates are the crusher fines and natural sand commonly available at most quarries and HMA plant sites. We can design a Strata interlayer using the fine aggregates available in your area. We use Stylink technology to formulate modified binders with a strong, elastic polymer in asphalt network that doesn’t separate in the tank and that prevents segregation in the field.
While the Strata interlayer can withstand traffic for a few days, it is not designed to be a surface course. The overlay is needed to provide the wearing course, and should be designed to meet the expected traffic demands that will be placed on that pavement.
Our Strata system is designed to be rich in Stylink® binder, and is therefore an excellent adhesive and waterproofing material. There is little risk of delamination, and the interlayer is impermeable. It is therefore ideally suited for use as an interlayer between the existing PCC and the HMA wearing course.
Proven in the Field
This technology has been used in several projects in the U.S., with preliminary outstanding results. The Strata sections have consistently shown longer resistance to reflective cracking than other crack relief methods. Data is being gathered from projects throughout the U.S. The crack map shows that the Strata section on New Jersey Route 10 exhibited significantly less reflective cracking after two years than the standard HMA overlay control.