The NovaChip paver has a receiving hopper that the ultrathin material is placed; the ultrathin hot mix is then moved by four screw-type auger conveyors to the rear of the NovaChip paver.
Once the ultrathin bonded material is placed in the screed, it?s struck-off directly into the path of the polymer modified emulsion membrane.
The polymer modified emulsion membrane is applied by way of pressurized spray bar that is located directly behind the rear wheels of the NovaChip paver but in front of the hot mix paving screed. One of the unique parts of this NovaChip paver is the location of the spray bar, in normal pavement lay-down operations the tack coat is sprayed onto the old roadway surface.
The trucks hauling the new mix to the hot mix paver must then reverse through the tack coat to place their load into the paver. The resulting consequence is that a portion of the tack is then tracked onto adjacent highways or streets. A 3,000-gallon storage tanker in the front of the NovaChip paver provides the needed polymer modified emulsion. The application rate is calibrated into the machines computer. The polymer-modified emulsion is sprayed at around 150 degrees F.
Immediately after the polymer-modified emulsion is sprayed onto the surface of the old pavement, the ultrathin bonded wearing course is placed at 310 degrees F. The two materials immediately bond to form a thin surface on the old pavement. The paver operates at around 60 to 120 fpm depending on conditions, like depth of the lift of mix. The paver screed is hydraulically extendable, so the process can match varying widths of roadway.
The mix should be applied at a temperature of 290 to 330 degrees F. Because the mix is placed very thin, it will cool rapidly.
If the screed is not preheated, there will be difficulty at startup. Rollers should be compacting the material as close to the NovaChip paver as safely possible. To maintain a smooth mat, one should keep from stopping the NovaChip paver?s forward movement; stopping the paver will also hinder production. Logistics are, therefore very important.
Sufficient nurse trucks for the emulsion should be available, and plant production and lay down should be balanced so that the mix can be placed without stopping.
It?s very important not to vibrate the ultrathin bonded wearing course, the matrix is stone-on-stone and crushing the aggregate through vibration will cause problems.
There are normally two steel drum rollers, both rollers should be around 10 tons in weight. These rollers are operated in the static mode only. In some cases, vibrating the longitudinal joint or seam is allowed.
The process of compaction is to merely ?seat? the aggregate in the mix and not crush the aggregate. In some cases, a pneumatic-tired roller can be used to assist the compaction effort. The compaction effort should start immediately after the ultrathin bonded wearing material is laid.