He can use lubrication when he first starts…until the tires get up to temperature.”Volvo’s Density Direct features an 8X10 touch screen display and uses a GPS to track roller passes. As Ball mentioned earlier, it’s more of a numbers game now than it used to be. “Rubber tire rollers are typically not used on SMA mixes,” Brown shared. The pass on the left side of the panel stops in an arc and the compactor returns on the same path.

Poor rolling practice can be overcome by The length of the compactor drum is not the true measure of the productive capacity of the asphalt rolling machine. This should be based on width of the mat and width of the rollers, as well as the mix design parameters (including its delivery temperature), paving speed, and ambient and ground temperatures. Considering the pneumatic tired roller will likely operate in the intermediate position, it should not experience the hottest temperatures of the mat. The mechanism within allows the drum to “jump up and down” and impact the pavement. Brown described it as “similar to bleeding or a fat spot.” If you roll this area, the fat spot becomes permanent and friction at that spot is lessened. The next forward pass is on the right side of the panel, passing the previous forward pass, with an arc toward the center of the panel. If misalignment of the screed sections leaves a line in the mat, the roller operator is called on to smooth it out. “If they just can’t slow down, they may have to adjust the pattern. That means the roller operator’s equipment must be in perfect working order, as we discussed in September, and his skills must be honed with excellent training and continued review. All the data is documented for subsequent analysis. “Some states use vibratory rollers and some do not allow vibratory rollers to be used due to potential for breakdown of aggregate. The most efficient machine gets the passes accomplished before the mat cools.Check out a couple rolling pattern ideas from Bomag Americas in figures 1 and 2 below.Figure 1.

Your dealer can tell you the specifications for your model’s tire.Now here’s a tip for keeping tire pressure even throughout the shift. Roll the end of each subsequent pass beyond the end of the adjacent and previous pass.This is also shown in Figure 2. Figure 2 shows the technique. Also notice that the roller operator isn’t letting the paver get too far ahead. Ball explained that it’s too narrow to achieve compaction before the mat cools.To get the most efficient number of roller passes applied to the mat, you want a drum of sufficient width. If the contractor does not own a plant and must purchase mix from another producer, the number of tons of mix to be purchased is usually a contract item and of predictable supply.Contractors also know the size and capacity of the transport trucks used to deliver hot mix asphalt (HMA) to the project. Any rolling instructor worth his salt will tell you compaction depends on time and temperature.

The danger of picking up material and leaving divots in the mat is too great because the mat is too hot; you’re using too much water for lubrication, which results in ribboning.

If one reads lower than another (80 instead of 120), it’s flat. Unfortunately, even the best operator will fail to achieve uniform pavement density when making a rolling pattern like the one shown, since the compaction forces are not evenly applied across the width of the panel. Remember, the higher the ply, the stronger the tire. Develop Your Best Rolling Pattern Part 1. Your QC technician needs to hold a meeting with the roller operators to start the day off right. •Paver makes single pass •Roller pattern requires 3-7 passes ishes Idaho Asphalt Conference 18.