Flexible Pavements and Recycling Solutions
Flexible pavements are usually synonymous with asphalt pavements or “blacktop.” It is a common pavement wearing surface and can be a great solution for the right application. Asphalt requires proper maintenance throughout the years to maximize its lifespan. Recycling asphalt is a very common practice and can be done in countless ways. Many flexible pavement designs utilize a recycled or stabilized base due to the extended lifespan, cheaper construction, and faster construction that often comes when paving asphalt on a recycled pavement solution. We can help you understand how to pair your flexible pavement with the appropriate recycled base material.
Full Depth Recycling (FDR)
FDR is a cost effective, long-lasting, sustainable alternative to deep rehabilitation or removal and replacement techniques. It is an engineered rehabilitation technique in which the old asphalt pavement and a predetermined portion of the underlying materials (base, subbase and/or subgrade) is uniformly pulverized and blended to provide an upgraded, homogeneous material. The Reclaimed materials are improved and strengthened by using a mechanical, chemical (like cement), or bituminous stabilizer. FDR is mostly known for its ability to fix base failures or roads in poor condition, but also a viable design process for increasing the structural capacity of a pavement in good condition. Its economics allow it to be a competitive solution for most rehabilitation needs. An FDR layer is base layer that is capped with varying wearing surfaces depending on the application.
40%-80% Less Expensive than Conventional Techniques - Reuses 100% of the Existing Materials - Trucking Reduction of 40:1 - Structural Loading Capacity Improvement – Slope & Grade Correction
Cold In-Place Recycling (CIR)
CIR is a cost-effective, long-lasting, sustainable alternative to conventional maintenance and rehabilitation techniques. Cold In-place recycling is a process that cold mills and recycles the top 2-5 inches of asphalt using a continuous train operation. Through the complete reuse of existing material, CIR greatly reduces trucking, time, and natural resources to significantly lower project costs. Generally, virtually any road that is a candidate for mill & fill is a candidate for CIR. A CIR layer acts as a base lift that usually requires a surfacing overlay or wearing application.
20%-50% Cost Savings - Reuses up to 100% of the Existing Pavement Materials - 20-40% Faster Construction
Cold Central Plant Recycling (CCPR)
CCPR is another form of recycling for the existing asphalt pavement, similar to CIR, except this process takes place at a central location using a stationary cold mix plant (often brought to the job site) and a stockpile of recycled asphalt pavement (RAP). This is an appropriate method when existing pavement cannot be recycled in-place due to logistical reasons, multiple lifts of base are needed, or if the existing asphalt must be removed to allow treatment of underlying materials. CCPR pairs well with FDR in a “multi-layer/inverted” pavement structure and helps balance a variable depth project site.
Versatile - Pairs with FDR for Maximum Recycling - Increased Production During Construction
Soil/Subgrade Stabilization
Often, subgrade soil is too wet, exhibits poor workability, is prone to expansion, and/or lacks sufficient strength. Chemical additives such as cement can be added to these soils to dry up the matrix and improve the workability of the soil.
Soil Stabilization refers to the process of adding and mixing the chemical additive into the soil to allow a mechanical strengthening, an aerating and absorption of water, and/or a chemical reaction occurs exchanging ions and reducing the negative plasticity index (PI) and shrink/swell potential of a reactive soil. These improvements often result in a slight increase in shear strength of the soil. By using chemicals, like cement, a significant strength increase can be achieved thus improving load bearing capacity of subgrade to support pavements and foundations. Cement soil stabilization is also an accepted practice for mitigating certain types of hazardous materials in-place.
20%-40% Cost Savings Compared to Removal and Replacement - 100% Reuse of Existing Materials - Reduced Trucking – Hazard Mitigation
Connect with a CNCA Expert
Clay Slocum
Director of Engineering
