- Generally speaking, any asphalt roadways with good structural strength coupled with at least 100mm - 150mm of existing asphalt material are good candidates. However, each road must be evaluated on an individual basis to determine whether or not it is a good candidate for the process. Use of this process for heavy-duty roads or high-speed, high-traffic roads may not be appropriate.
- The most common additive is asphalt emulsion; however, lime slurry, portland cement, fly ash or a combination of these additives are also used.
What types of problems can recycling correct?
- Recycling can correct problems such as rutting, raveling, polishing of aggregates, bleeding, shoving as well as poor profiling. Basically any type of surface defect.
- Most properly designed recycled pavements last as long as a comparable virgin hot-mix pavement.
- The equipment is limited to 250mm - 300 mm. However, the primary limitation is curing and compaction. The deeper you cold recycle, the more compaction equipment is necessary. Also, aeration may be necessary for curing on deep recycle projects.
- The end product usually looks like a base paving material. In some cases a fog seal is placed on the surface which protects it from the elements as well as giving the material a uniform black surface appearance.
- The amount of additive is determined by the mix designs from material sampled from the roadway. Typical asphalt emulsion contents range from 13% by weight of the RAP. When cement or lime are used typical application rates are from 13%. When fly ash is the additive the application rate varies from 5 - 12%.
- Typically cost savings vary from 25% to 33% over other equivalent alternatives.
What are the environmental benefits of CIPR?
- No heating is used during the process thereby reducing the use of fossil fuels and also reducing air pollution. Also, the existing aggregate and asphalt cement is reused thereby decreasing and/or eliminating the need for virgin aggregate and asphalt cement in the process. Total energy savings of from 40% to 50% can be achieved using this processes versus conventional approaches.
- Traffic is kept off the finished product until compaction is complete. There is no need to wait for the material to cool or setup because it is not heated. This helps facilitate the speedy return to traffic and reduces user delays. The recycled lane may be opened to traffic one hour after completion of the day's work.
How many years has the process been used?
- Various forms of cold recycling have been used for many years. The advanced cold recycling systems with sophisticated processing and additive controls have been around since the early 1980's.
- CIPR has been used at night. Depending on the type of additive in use and the weather conditions curing may be slower. However, it has been successfully performed.
- The weather and temperature limitations will vary depending on the additives in use. Generally, asphalt emulsions are used when the temperature is 18ºC and rising and the conditions are not rainy or wet. Each project should be evaluated individually by a local expert to determine its viability.
- It is recommended that all Cold In-Place Recycling projects receive a seal or overlay. A pavement design is required to determine how much if any overlay is necessary.
- It is generally recommended that the moisture content of the recycled material not be greater than 1.5 % above the "free moisture" content of the original existing pavement before overlay or sealing. Light fog seals are commonly placed the same day as construction, however.
- A certain amount of reprofiling may be performed with the Cold In-Place Recycling process. Severe geometrical problems cannot be rectified without premilling the surface prior to Cold In-Place Recycling.
- Yes, JKR/SPJ/2008-S4
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