NSW-based business Grade Control may have started out focusing on simple blade indicator systems for graders but founder Phil Polmear has continued to reinvent the business and now supplies a more diverse range of products to councils and contractors.
While the Sandvik System 2000 Carbide Tip blade systems remain a core product, along with the Free-Roll grader-mounted compactor, a relatively recent addition to the product line is something a little outside the initial grader focus. However, it is proving to be a real winner in the area of cost-effective road maintenance in regional areas (although its application is by no means restricted to those areas).
The Asphalt Zipper took some time to be accepted, although it is widely used in the US. It is relatively simple in concept, comprising a milling drum with its own engine, which is hitched to a backhoe or wheel loader – depending on the drum size – but supported on skids during operation.
There are three models: the AZ-300B, AZ-500B and AZ-600B; with the drum widths being 750mm, 1200mm and 1800mm respectively. Applications include full-depth reclamation, stabilisation, asphalt grinding and milling; with up to 194kW available on the AZ-600B, which has a cutting depth of up to 305mm.
Some advantages of the Asphalt Zipper for regional areas are:
- It generally avoids the need for large specialised equipment to be brought into the region, avoiding significant transport costs and keeping the work in the region.
- The host machines are readily available in regional areas, and are only used to lift the Asphalt Zipper and guide it during operation – not power it.
- It provides long-term solutions rather than “quick fixes”.
- Local materials can generally be used, avoiding the need to cart away existing material and import new material.
- It is versatile in the range of applications that it can be used for.
A spraybar provides moisture control, and additional materials required to improve the pavement can be spread over the existing road and blended with it to provide an improved based that can be worked, compacted and sealed.
Polmear cautions that at times it may be necessary to temporarily remove materials so that the depth of pulverised can be compacted effectively, before the material is reinstated and compacted as another layer.
This approach can be taken to improving the shoulders to widen roads, and providing a long-term fix for pothole problems; and it is a cost-effective alternative to digging out and replacing existing materials.
Another application that is becoming more popular is opening utility trenches in asphalt, not only cutting the pavement but also pulverising it into a size that can often be re-used as bedding or backfill, significantly reducing or eliminating the costs of disposal of existing material and importing of bedding and backfill material (approval has been gained in the US for its use as backfill material). There are also significant time savings compared to saw cutting and breaking out pavement in chunks.
First user confirms benefits
Richard Jane of Gwydir Shire (New England region of NSW) was the first to see merit in the Asphalt Zipper when Grade Control first advertised it in the lead-up to a Civenex exhibition.
At that time, the first unit hadn’t arrived in the country but Jane’s interest secured the first trial. With acceptance from the road workers, this trial led to the first sale in Australia.
The shire uses its Asphalt Zipper AZ-500B with 203hp Cummins engine exclusively for heavy patching work up to 200mm depth. It replaced the previous method of digging out and replacing a failed section of road. The shire had also tried using a milling attachment on a skid steer loader.
The Asphalt Zipper is generally used with a 20-year-old Cat 936F loader, although a 924 loader is sometimes called on for the work. One thing that Richard noted in comparing the Asphalt Zipper with its own power plant to other attachments running off the auxiliary hydraulics is that when the attachment is working hard, the elevated engine speed also increases the travel speed of the tractor or loader being used, which is not ideal for milling. With the Asphalt Zipper, loader travel speed is completely independent of the Asphalt Zipper operation, and Jane states that he would never go back to a single engine system.
The heavy patching crew comprises the Asphalt Zipper with separate operators for the loader and zipper, a grader and operator and a water truck and driver. A compactor follows behind, and a separate traffic management crew is used as required.
Jane’s approach to the heavy patching is that the failure is most likely a result of a subgrade problem, and thus the repair should bridge over the problem area. As a result, 2½-3% builders cement is blended into the existing material using the Asphalt Zipper, and water is incorporated either through the spray bar on the Asphalt Zipper or directly via the water truck.
To create the bridge, the repair generally extends a metre beyond each end of the failure, and the repair width is generally half the width of the road.
Heavy patching is done for 7-8 months of the year, with a value of $300-400k of repairs undertaken each year. The cost of patching has reduced from $38/sq.m. for dig/replace to $20/sq.m. with the Asphalt Zipper.
Jane cannot recall any subsequent failure of heavy patching work undertaken with the Asphalt Zipper.
New franchise
Grade Controls has recently taken on distribution of the established US-made Road Widener skid steer attachment for road widening and material placement.
Road Widener LLC. was founded by two experienced road construction professionals, who graduated from working from their garage to a modern fabrication facility in Wisconsin that produces attachments for the US domestic and export markets, with the technology covered by a number of US patents.
Two models are available to cover single-sided discharge and discharge to either the left or right side. The attachment has a steerable front end and can handle gravel, asphalt (it has a heat-rated belt) and soil (it can be used for trench backfill).
Road Widener LLC is keen to see its widener attachments operating in Australia, where many conditions are similar to those in which the attachment operates successfully in the US.
Polmear believes that despite the current unfavourable exchange rate, the Road Widener is very competitively priced for the Australian market and has an operating weight that makes it suitable for use with a broad range of skid steers available on the Australian market.
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