 This is the first of two programs covering bituminous seal coats. Here in part one, we'll look at preparing the road surface, setting up traffic control, buying the liquid asphalt, placing the cover material, and running test strips. Part two will discuss transverse and longitudinal joints, operation, opening the seal coat to traffic, but before we get to all the details, here's an overview of the whole process, beginning with preparing the road surface. Only it's done weeks or even months ahead of the actual operation. Basically, the surface has to be smooth and level, so all potholes have to be repaired as well as any large cracks. Preparations can even include lane leveling or base repair. Again, the surface has to be smooth and level. After the repairs have been made, the surface is cleaned. The cleaning is usually done a day or so before seal coating. The important point here is that the surface be as clean as possible. Placing a seal coat over a dirty surface would be like painting a house without sanding. It won't stick, so it won't last. Okay, so the first step is to prepare the road surface, and it normally includes both repairs and cleaning. The next step is to set up everything necessary for safe traffic control. That, of course, includes all the proper signs, but in addition, a pilot car has to be ready to go from the outset. Traffic has to be led through the work area throughout the seal coat operation. The next three steps have to follow closely together. The liquid asphalt is applied, the cover material is placed, and the surface is rolled. When the surface is clean, the liquid asphalt can be applied. I would say that this is the most critical part of the operation, but as you'll see, each and every step of the operation is critical. If any part isn't done exactly right and at the right time, the cover material will not stay in place. The application has to be smooth and uniform. No lightly covered areas and no puddles. Here again, you can see why the early preparations are so important. If there were any bumps or depressions in the surface, the application would not be uniform. The amount of liquid asphalt that's applied over a given area is referred to as the application rate, and getting the right application rate is one of the most critical parts of the whole job. If there's too much, it'll bleed through the cover material and start tracking and rolling the chips. And if there's too little, the liquid asphalt can't hold the cover material in place. The application rate will hold the cover material in place without bleeding through the surface. Ideally, about three-quarters of each stone should be embedded in the liquid asphalt. The liquid asphalt that we use most often is in emulsion. And the important thing to know about emotions is that they contain water. As you can see, the emotion is brown when it's applied. Soon afterward, it turns black. The change in color signifies that the emotion has lost its water content. As the water evaporates, the asphalt rises up around the cover material. That's mainly how we get three-quarters of each stone embedded. So for the process to work, the cover material has to be placed while the emulsion is still brown before the water evaporates. So the chip spreader has to follow closely behind the distributor, no more than 200 feet. That way, you can be sure that the chips will be placed in time. If the spreader is too far away and the emulsion turns black, the stones will not penetrate. The speed of the spreader is also important. The material has to be placed so that it stays put when it hits the surface. If the spreader speed is too fast, the material will roll when it hits. And that happens, the stones get covered with asphalt. Of course, the asphalt is sticky, so the aggregates will be picked off the surface by both the rollers and the traffic. So a speed of about six miles per hour usually works best. As I said, it's important that the cover material be placed as soon as possible after the liquid asphalt has been applied. So the only solution is to hold the speed of the distributor to about six miles per hour. That way, the material stays where it's put and the chip spreader stays close to the distributor. As I said, the chip spreader should not be more than 200 feet from the distributor, but the closer they stay together, the better. The application of the cover material, like the liquid asphalt, has to be uniform. Again, about three quarters of each stone should be embedded in the liquid asphalt. But beyond that, the stones have to be placed close together so that only a small amount of liquid asphalt shows through. But the chip spreader can't do it all. That's why there's one more step. Rollers follow closely behind the spreader to make sure that all the material is firmly seated in the liquid asphalt and that the stones are lying flat, not one on top of another. Now, just because the material is well seated, that doesn't mean that it's not going anywhere. Remember, the liquid asphalt is still hardening around it so the new seal coat has to be protected for a while. Traffic can be allowed over it, but a pilot vehicle has to be used to keep the speed down no more than 25 miles per hour. If traffic were allowed to go at its normal pace, the cover material would be thrown off the side of the road. And there you have it, the completed job. But as I said, that's just a quick look at the overall procedure. Now let's go back and take a look at each step in detail, beginning with preparations. You'll remember that the surface has to be both smooth and level before seal coating begins and that any repairs should be done well in advance. Doing the repairs early allows time for them to cure. For example, waiting a few weeks after pothole patching gives the patch a chance to be completely cured out. If we didn't wait for the patch to cure, the liquid asphalt from the patch would most likely bleed through the new seal coat. But even with all the repairs made, there's still a lot to do before seal coating. Here's what you need to be concerned with. The weather forecast, the condition of the cover material, air and pavement temperatures, and traffic control. Let's start with the weather forecast. We're starting here because the weather plays a tremendously important role in seal coating. In fact, we don't even think about putting down a seal coat except in June, July, and August. These are the only months that both the day and night temperatures are warm enough. The weather is so important because of the liquid asphalt. Cold weather, rain, or any moisture will keep the asphalt from setting up at all. Of course, if the liquid asphalt doesn't set, it can't hold the material in place. So here's the rule. Check the forecast. If it's supposed to rain, forget it. And if the nighttime temperature is expected to go below 50 degrees, forget it. If the forecast is good, you can check the cover material. Two of the most important things about the cover material are that it be clean and damp. Here's why. The liquid asphalt has to bond not only with the pavement, but also with the cover material. And if there's dirt or dust on the cover material, it won't stick. So the cover material should be hosed down the day or so before seal coating. That way, it's not dripping wet, just damp. Be careful not to water the chips too much. Excess water will create mud at the bottom of the stockpile and contaminate the cover material. The best way to avoid contamination is to place the stockpile on a hard surface. Okay, it's the morning of the day you're going to seal coat. The weather is good, the forecast is good, and the cover material is ready. Now, before doing anything else, check the temperature of the road surface and the air temperature in the shade. Both temperatures have to be at least 70 degrees. If it's any cooler, the liquid asphalt won't set up and the cover material won't stay in place. As for traffic control, well, we can do a whole program just on that. But there are a few points that apply to all seal coat jobs. Make sure all the signs and devices are in place before the equipment gets to the job site. Remember, that includes temporary pavement markings. Motorists must have the benefit of these markings until permanent lane lines can be applied. Second, there's no way to safely place a seal coat without flaggers and a pilot car. So be sure that flagger symbol signs are placed on both ends of the work area and that the flaggers and the pilot car are ready to go from the outset. One more thing, loose chips are a real danger to passing cars. So always put up fresh oil and loose gravel signs on both ends of the work area. The motorists have to be warned to use caution when driving over new seal coats. Okay, the forecast is good. The pavement temperature is above 70 degrees. The air temperature in the shade is above 70 degrees. The cover material is damp and all the traffic control devices are in place. Now you're ready to seal coat. The first step is to run a test strip to find the best application rates for the liquid asphalt and the cover material. As a general guideline, you'll need between three and four-tenths of a gallon per square yard of liquid asphalt and between 20 and 25 pounds of cover material per square yard. After both materials have been applied, you can see if the rates are correct by closely examining the surface. Remember, the cover material should be about three quarters embedded in the liquid asphalt as you see here. If there's too much or not enough asphalt, you'll have to change the rate and run another test strip. Of course, there are a number of calculations that have to be made to verify the rate of the liquid asphalt. Your instructor will go over them in detail later on. Now let's look at the procedure for checking the application of the cover material. Basically, all you have to do is put something to collect the cover material at the beginning of the test strip, let the chip spreader go over it and then weigh the cover material. On this job, the crew is using a frame with an inside dimension of exactly one square yard. So all they have to do is place the frame over a piece of fabric to collect the material. After the chip spreader passes over the frame, all the excess material outside the frame is removed. To find the application rate, all that's left to do is weigh the material. In this case, the cover material weighs 22 pounds so the application rate is 22 pounds per square yard. But let's back up a minute. Even though the main purpose of the test strip is to determine the application rates, we also have to see that everything else is running smoothly. And as I said earlier, timing and speed are crucial to a successful chip application. The chip spreader should stay within 200 feet of the distributor and go slow enough so that the stones don't turn when they hit the surface. Rollers should follow as close to the spreader as possible so that the cover material is firmly embedded in the liquid asphalt. From here on out, seal coating is a continuous operation. Again, the spreader and the distributor should travel at the same speed. That way, the oil distributor and the chip spreader can stay within 200 feet of each other. And that brings us to the end of part one. In part two, we'll look at transverse and longitudinal joints, truck operation, opening the seal coat to traffic, and cleanup. This is part two of the course covering batuminous seal coats. In this program, we'll look at transverse and longitudinal joints, opening the seal coat to traffic, and cleanup. Start with transverse joints. The first thing you should know is that every application that joins a previous application has to begin on building paper. In other words, every application other than the first one. The reason is simple but important. We have to avoid spraying liquid asphalt over the cover material already in place. If we did not start the application on building paper, we would be placing one application over another and building a bump in the surface. So at the end of every application, shovel away the excess material to where the coverage is uniform. And it's best to do it right away before the liquid asphalt sets. That's the best way to get the edge neat and square. Then all you have to do is sweep the area and place building paper across the lane and secure it. And that's the procedure for transverse joints. Now let's look at longitudinal joints. You've probably noticed that there is a small section of liquid asphalt that the chip spreader does not cover on the first pass. This small section is known as the meat line. The first application is left uncovered because there's not enough liquid asphalt to hold the cover material in place. As you can see, there's no overlap at the far side of the application. The chip spreader operator has to be careful, though, to make the meat line only as wide as the spray from the last nozzle, about six inches. You'll also notice that the first application is made in the left lane. That's so both the distributor and chip spreader operators can easily see the meat line on the second pass. The second pass has to be made so that only the last nozzle sprays the meat line. This double spraying of the meat line gives the surface the coverage we need and ties the two applications together. As for the chip spreader, the second pass should be made so that the entire meat line is covered, but without overlapping the first application by more than an inch or so. And those are the procedures for constructing transverse and longitudinal joints. To review, every application joining another application has to begin on building paper. And the building paper has to be removed before the chip spreader reaches it. The meat line should be only as wide as the spray from the last nozzle. The distributor should line up on the second pass so that only the last nozzle sprays the meat line. And the chip spreader should cover the meat line completely without overlapping the first application too much. Now let's look at truck operation. As I said in the first program, each and every part of seal coating is critical to the success of the job. And that certainly holds for the truck operators. In fact, the operation of the trucks can make or break the whole job. Obviously, the main job of the trucks is to load the chip spreader, but there's a whole lot more to it than that. To begin with, the trucks can help considerably in rolling the new seal coat. Notice the position of the trucks as they back toward the spreader. They're not in a straight line. Instead, they're staggered across the road, offsetting their wheels so each truck rolls a different part of the surface. Beyond that, trucks have to be careful not to damage the seal coat. So the slower the speed, the better. And each turn and stop should be as gradual as possible. Remember, any sudden movement on a new seal coat will dislodge the cover material. In addition, all operators have to do whatever is necessary to avoid driving over the meat line when returning to load the chip spreader. And that brings us to rolling. As you've just seen with the trucks, the rollers should also be staggered. At a minimum, there should be at least two 11-wheel rollers with ballast if possible. The roller operators should establish rolling patterns so that they don't interfere with trucks entering and leaving the worksite. And so that the entire surface is rolled four times by each roller. Here again, the rollers should go slow to avoid throwing the chips. And all stops and turns should be made gradually. Of course, nothing helps the rolling operation more than using equipment in good condition. As you can see here, the scrapers are functioning properly and there's no build-up of material on the wheels. Now let's look at opening the seal coat to traffic. The first thing to do is to remove the protective covering on the temporary tabs. This exposes the reflective strips so the motorists can see them at night. Traffic should be allowed on the new seal coat as soon as possible to further help roll the surface. But there are a few important things to keep in mind. First, the flaggers should not allow a vehicle to catch up with the cars already being led through the job. That's because the vehicle will likely speed up to catch the traffic and then slow down quickly when it gets there, both of which damage the seal coat. Work should progress so the traffic is never held for more than 15 minutes. Flaggers should also be careful not to set up their station on a hill. Stopping and starting traffic here is sure to damage the surface. Second, the pilot car's main responsibility is to lead the traffic slowly, no more than 20 miles per hour. And when the pilot car has to lead traffic over the same portion of the seal coat several times, the pilot car should not drive in the same place. Instead, the pilot car should drive to one side of the lane and then the other. That way, the surface gets rolled more evenly and there's less chance of the liquid asphalt bleeding through because of driving over the same place too many times before it has a chance to set up. The pilot cars should continue to lead traffic over the road for about two hours after the seal coat has been placed to give the liquid asphalt time to set. Of course, the wind and temperature affect the time it takes for it to set, so it may be necessary to use the pilot car longer in cool or damp weather. Now, clean up. As soon as possible after the liquid asphalt is set and the pavement is cooled, preferably the next morning, the surface should be lightly broomed to remove any excess chips. But don't ever take down the advisory speed sign until all the loose chips are gone. Flying chips will break windshields. And those are the basic steps of operation, but there are a few more points I want to make before we finish. This job requires a great deal of teamwork. As you've seen, the chip spreader has to follow as close as possible behind the distributor. And the only way to keep up is to have a constant supply of trucks to load the chipper. Continuous operation is critical, and everyone has to know where they should be all the time. In addition, everyone should be on the lookout for any problems. The two most common problems to look for are excessive chips and bleeding. Excessive chips can be removed easily enough by brooming. And if the liquid asphalt begins bleeding through the surface, a light application of sand can help reduce tracking. The point is, your supervisor can't be everywhere. So if you see anything that doesn't look right, let your supervisor know. The best time to correct any problem is right away. And that brings us to the end of the training course on bituminous seal coats. Try to keep the points you've seen here in mind. Good seal coats are a result of each and every person's contribution on the crew.