Monday | December 11, 2017

Revamp Concrete Truck for Asphalt Medians, Finish Work

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When the paving crew takes a haul truck into a congested city work zone, overhead traffic lights, signs and power lines become a hindrance to lifting the truck body to charge the hopper. You can overcome that safety hazard by using a live-bottom haul truck that moves material along a conveyor from the front of the bed to back of the bed. The mix then falls out a chute through a door or flap at the back of the bed to charge the hopper. Contractors understand this concept.

Then the paving crew comes to a tight space where the haul truck of 18 to 23 tons of mix won’t fit nicely whether the body stays horizontal or not. Or perhaps you’ve reached an area where the paver can’t back in nicely and pull a good mat, and you need to meter mix to the spot. You can overcome the gap by adding extra laborers for the shift to take a Bobcat bucket of mix from the truck to the area in question and break it down by hand. Contractors understand this concept.

To make handwork easier for the team, you can take wheel barrow after wheel barrow of mix to the area and dump the mix in a more measured process for the laborers. We all know asphalt mix isn’t easy to rake into a smooth mat when it’s dumped by a skid steer or haul truck in a mass, so the wheel barrow or shovel method takes more time, but gives the crew a better chance at success. This is especially true for paving in areas such as guard rails where a large pile or two of mix would be a nightmare to work with. Contractors understand this concept as well.

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The team at Tilcon Connecticut recently took a new approach to moving material from the haul truck to more troublesome locations where contractors are asked to pave. In this example, the crew paves the median at a completed mainline paving project on a state highway. They’ve refurbished a concrete truck so it can deliver hot or warm-mix asphalt. Here’s how you can make this work for your smaller projects or finish work.

Fix the Truck
First, Tilcon mechanics took an existing concrete truck and made some modifications. They can use the chute for dispensing material, but their changes make it possible for that material to be HMA or WMA.

They removed the cement mixer. In its place, they installed a live-bottom truck body, but they placed it backwards. In other words, the conveyor moves material from the back of the haul body to the front, where it empties down a chute to the snorkel.

Next, they bought the snorkel with an auger in it and affixed it to the front of the truck where the concrete chute could deliver mix into it. The snorkel acts like a radial stacker because it can be maneuvered up and down, and right and left by the joystick control in the cab. They use a hydraulic arm to move the snorkel.

Now when the team has a difficult area to pave, such as a highway median, they don’t have to place ramps to get a 200-pound wheel barrow of cooling material into place. Instead of taking a full day to place 18 tons, the crew accomplished the project depicted here before noon.

Get the Crew Ready
One of the most important aspects of using this converted truck is the training of the driver. He’s not merely driving a truck from the plant to the jobsite. He’s meticulously distributing mix for the laborers. He has his hand on the one mechanism that can make life easy or difficult for the crew. For the project shown in these pictures, the median was to be 2 inches compacted with a dome in the middle.

Notice, there were two workers on each side of the front of the machine/truck because it was a wide operation—one raker on each side and one lute man on each side. This frees up additional laborers who would have been running mix to and from the site for other crews/projects.

The rakers used rakes that have 14 three-inch teeth to break down the material, spreading it evenly where the snorkel had dropped it for them. The lute men used 36-inch-wide lutes to further smooth the surface of the mat for the roller operator. The roller operator came along after them with a plate compactor to seal the edges along the curb first. Next, he got on a sidewalk-appropriate roller and rolled from the sides to the center, accommodating the slight slope of the dome.

Without the driver’s gentle touch and experience, this project could have been a difficult one for the laborers. Too much mix in one place means extra work and possibly a mound that can’t be smoothed or rolled out. The importance of delivering perishable material correctly is one of the reasons Tilcon employs its own truck drivers. The gentleman in these pictures has been trained for this job and his crew can depend on him as a strong link in their chain to build a top quality pavement.

John Ball is the proprietor of Top Quality Paving, Manchester, New Hampshire. He provides personal, on-site paving consulting services around the United States and into Canada. For more information, contact him at (603) 493-1458 or tqpaving@yahoo.com.

Use a Snorkel as a Radial Stacker
To create the snorkel truck for easier tight-space paving, Tilcon modified a concrete truck to suit their crew’s needs.
1.    They took the cement mixer off an old cement truck.
2.    They installed a live-body conveyor “facing forward” in place of the mixer.
3.    They installed a snorkel with an auger on the front of the truck, under the driver’s cab.

The snorkel functions like a radial stacker at the driver’s command. He uses a joystick to move the snorkel up or down, left or right, as the laborers need mix distributed ahead of the vehicle. This allows the rakers and lute men to break down and smooth out the mat more easily than if they were working with piles from a skid steer bucket or multiple wheel barrow loads. This also eliminates the need to back a haul truck into the area, dump mix, pull forward, move a few feet, back up again, dump mix, pull forward, etc. When paving 50 feet per ton to put asphalt under guardrails in medians and on the side of roads, the auger feeding material is a huge timesaver.

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