![]() Type I is used for maximum crack penetration.The three generally accepted gradings used for slurry mixtures are: The aggregate used in slurry seal must be clean, angular, durable, well grades, and uniform. Spreader boxes may be equipped with hydraulically-powered augers to keep the slurry in motion and help keep the mixture uniformly spread across the spreader box width. The box is equipped with flexible squeegees and a device for adjustable width. The slurry machine has a continuous-flow mixing unit, either single or double pugmill, from which the slurry is discharged into a spreader box. They are truck-mounted units with separate storage tanks, bins, and metering systems for emulsified asphalt, water aggregate and mineral filler. Certain basic features are common to all batch type slurry machines. It also discharges the thoroughly mixed materials on to the prepared surface. It is capable of delivering accurately to the mixing chamber predetermined amounts of aggregate, mineral filler (if required), water, and asphalt emulsion. The machine used for production of the slurry seal is self-contained, continuous-flow mixing unit. It comes directly from a traveling mixing plant into an attached spreader box that spreads the slurry by a squeegee-type action. The slurry is usually applied in a thickness of 3 to 6 mm (1⁄8 to ¼ inches). In many cases, the relatively low cost of the treatment makes it practical to import aggregates for special effects, such as high skid resistance, color contrast and noise reduction.No need for manhole and other structure adjustments.Ability to correct minor surface irregularities.Excellent surface texture for paint striping.Slurry seal has a number of advantages some are listed below: This will lead to degradation and possibly contamination. When building a stockpile with a loader, the pile should not be made so high as to necessitate the loader driving on the material. To prevent overrun, the operator must be careful not to push the material over the edge of the pile. If delivered by conveyor belt, the pile is formed by pushing it into horizontal layers. If delivered by truck, the pile is formed by pushing the material into inclining layers. If this equipment is not available a dozer may substitute. Each layer of the layered stockpile will have the same segregation characteristics of a large conical pile, but the multiple layers mitigate segregation at the point of loading, and eliminate the need to reblend.Ī radial or telescopic conveyor can be used to construct a layered stockpile. The formation of a continuous layered stockpile will reduce the effects of segregation and eliminate the need to reblend the base before shipment. Careful and even loading of the truck bed will prevent further overrun segregation. ![]() Loading exclusively from either the front or back face of the stockpile will result in loads that are overly fine or overly coarse. This is best accomplished by drawing the material evenly from the edge of the pile perpendicular to the belt, thereby loading material from both the front and back face. When loading from a segregated stockpile, the loader operator will attempt to blend material from the fine and coarse portions. The resulting stockpile is segregated, with coarse particles settled at the toes, and fine particles in the center portion of the pile. Fine particles, which have settled against the surface of the conveyor belt, tend to cling to the belt and drop to the back face of the pile. In addition, the coarser particles hit the front face of the stockpile with a greater momentum, and roll down the outer edge of the pile, creating overrun: an accumulation of particles at the pile’s bottom edge, or toe. ![]() Coarse particles at the top of the material stream have a higher velocity as the material reaches the head pulley, and are thrown a greater distance. As the product is transported by conveyor, vibration and motion of the belt causes fine particles to settle on the bottom. Segregation occurs in the formation of a traditional conical stockpile. A ¾″ maximum base product exceeds this ratio and will readily segregate. Segregation of an aggregate product will likely occur where the ratio of the size of the largest particles to the size of the smallest exceeds 2:1. Segregation of aggregate base can lead to rejection or costly penalties for the producer, and base material is especially susceptible to segregation because of a greater variation in particle size than that of other stockpiled products. Specifications for ¾″ and 1 ½″ maximum base products are provided by Caltrans Section 26. It is composed approximately 50% coarse and 50% fine aggregate, and its tight compaction is achieved by an even gradation and angular particle shape. Aggregate base is placed between the compacted subgrade and the concrete or AC surface layer to provide support and drainage.
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