We are going to present two articles on paving for our readers. We tossed a coin, so this first one will concern concrete paving, and the second one, in the next issue of Grading & Excavation Contractor, will concern asphalt paving. Some reasons for looking seriously at paving projects now are valid for asphalt and concrete methods alike, but initially it may be wiser to discuss each method separately. For really helpful information about all matters concrete, I recommend your first contacts may be the American Concrete Pavement Association and the Portland Cement Association.
As earthmoving contracts have become scarcer and profit margins weaker, contractors are discovering that different types of projects can be the recipe for survival. Instead of looking for more earthmoving, contractors are looking for work that is a natural partner to their basic earthmoving expertise.
How About Paving?
There is always some earthmoving, some grading, dozing, and compaction before the actual paving begins, so what could be a better extension? A perfect example of this natural growth can be seen in the use of stringless technology for concrete paving. “Stringless technology is on the rise,” notes David Lipari, marketing coordinator for the Construction Division of Guntert & Zimmerman, one of the country’s leading manufacturers of paving equipment. “As you know, stringless operation has been used in the grading stages of paving for many years, but the systems were not sophisticated enough to achieve the tolerances.” Technologies with which you are familiar in earthmoving have become part of efficient paving, too. The tolerances mentioned for paving are most important. Paving for roads and streets must be accurate and finished to the level of accuracy stipulated in the contract. Do it well, and there are excellent rewards! The Nebraska Department of Transportation, for example, has awarded incentive payments for pavements that are produced as perfect as possible. For a deviation of 0 to 4 inches, a contractor can earn 106% of the payment. For 4 inches to 8 inches, that incentive payment is 104%, and 102% for 8 to 12 inches. Accuracy matters today in paving, possibly more than in any other sector of construction.
be an enormous advantage for paving
Another reason for the growing interest of earthmoving contractors in paving projects is that those projects are not all those large, dual-lane, several-miles-long designs we expect. Yes, there are still long, interstate paving projects but there is an increasing amount of shorter work, described by Lipari as “short cut-up projects that ensure proper traffic flow during construction.” This change has affected the equipment configuration, with manufacturers producing innovative machinery that allows contractors the flexibility to bid on these (smaller) projects. The S600 from Guntert & Zimmerman would be a good example of such machines.
The G&Z S600 Slipform Paver has a versatility that allows a contractor to switch quickly between applications and paving widths (where larger, more traditional pavers might restrict projects for which you can compete). Without sacrificing the performance advantages now seen as standard in G&Z’s medium and large pavers, the S600 can achieve excellent ride numbers on the toughest IRI and zero blanking band projects. The machine has a double telescopic, multipurpose tractor frame, and hose hinges for a nominal working range of 8 feet to 22 feet, with up to 7 feet of telescopic ability per side. With the use of bolt-in tractor frame extensions, the S600 tractor can extend up to 22 feet with a dowel bar inserter (DBI) with hydraulic vibrators or 26 feet with electric vibrators, and 29 feet, 5 inches without a DBI. The S600 has the narrowest profile on the market. The optional (and patented) TeleEnds: Telescopic Paving Kit End Sections provide a contractor the ability to perform paving-kit width changes rapidly, without the use of cranes, and with only a one- or two-person crew. Each TeleEnd gives 3 feet per side, or 6 feet for both sides. A width change that could usually take a three- to four-person crew six to 10 hours can be performed now by that one- or two-person crew in less than two hours, less than one hour for a width change involving a single spacer.
Maneuverability and the ability to do slipforming on a tight radius were two reasons for the development of Gomaco’s GP-2400 paver, introduced at last year’s Conexpo. This machine has been successful on such projects as parking lots, and the two-track design permits minimum machine transport width, much easier on-the-job mobility, and quick, safe performance. And it has shown good cost effectiveness. Gomaco, of course, is another manufacturer with a comprehensive range of paving equipment for all kinds of concrete paving and has gained high praise for the Gomaco G+ control system (on the GP-2400, by the way), which offers self-diagnostics for grade and steering. This control system was designed by the company’s own control specialists and offers easy-to-operate hardware with steering and travel dials. Buttons are used to control elevation. The “run” screen on the control panel shows various aspects of the paver, including leg positioning, steering, travel information, and grade information. In Gomaco’s range of concrete equipment you’ll find machines for slipforming concrete streets and highways, sidewalks, parking lots, curbs, gutters, airport runways, safety barriers, bridge parapets, irrigation canals, and recreational trails. The company also offers support equipment like concrete placers, placer/spreaders, grade trimmers, texturing and curing machines, and expert advice on all matters associated with concrete paving, large and small.
One area of paving that has its own expertise and equipment is curb-and-gutter work. You’ll come across much of that at housing estates and new developments. A name that always springs to mind in this area of paving is Power Curbers, whose 5700-C offers just about everything to a contractor. When the curb and gutter work has to be done in an area of high traffic (which seems to be more and more often these days) the standard single-lane pouring ability of the 5700-C means that the concrete (supply) truck can be lined up in front of the machine, and that is an excellent maneuver for both the paving crew and the traffic watching it work. Also on Power Curbers 5700-C you can choose to have pouring from either side while increases in both water and fuel capacity keeps the project going more smoothly for a longer time. There is a new electronic control system, using Smart Amps, that offers the simplicity of an analog system but has features of a digital system; the operator has more flexibility for adjusting sensitivity and accuracy. Display screens on the operator’s panel will show fault codes if there is a problem with a sensor, amplifier, or cord. Or you could choose a digital network controller with a large graphic display. On the 5700-C, the operator’s platform is raised not only to give better visibility but also to make the operator more comfortable, away from the heat of the engine.
The trimmer on this curb-and-gutter machine is sensibly accessible for maintenance; you remove the protective outside plate. This saves about 1.5 hours of maintenance time when you service the torque hub. Also, the repositioned height of the trimmer gives quicker set-up. The trimmer is mounted 7 inches further to the left now, giving the user the ability to trim and pour sidewalk of 6 feet. Further maintenance help comes because posts do not have to be removed from the machine to replace bushings; that saves about three or four hours per post in repair work and eliminates the need for a crane onsite. Power Curbers offers the Max package for the 5700-C. This option gives larger crawlers, all-crawler steering, and a special frame with secondary mounting location for a rear post. These and other features in the Max package let you pour barriers up to 8 feet and paving up to 12 feet.
As in every area of construction, there are specialized projects. Among those, we could name canal work (where Terex’s BidWell equipment has much to offer) and bridge repair, restoration, and rehabilitation. Allen Engineering has built a good reputation for its paving equipment for bridge deck finishers. The awful condition of many of our nation’s bridges has made headlines for years, and one day, possibly soon, those bridges will need attention. Specialization in bridge paving could become a profitable niche. Allen’s bridge deck finishers, like the Model 2836B, are favorites for high-volume bridge pours. There are several models available, and they are customizable to cope with almost any bridge deck job.
Another area for which Allen equipment is well known is that of the mechanical-drive riding trowel, where the operator sits on the trowel for smoothing concrete. These riders (like the MP 315) may be best known for work on slabs inside buildings, but they have also shown good results for projects like concrete paving lots, projects where concrete’s durability has earned praise from its owners. The MP315, launched this year, is called an entry-level riding trowel; there are models considerably larger. The trowel has gasoline engine (an air-cooled Honda GX690) and a heavy-duty drive train that is built into the easy-to-service frame. The two rotors for smoothing are 46 inches in diameter and have four non-overlapping blades. Variable rotor speeds go up to 145 rpm, and there is an electric-powered spray system for the application of retardant on the concrete.
There are excellent roads, sidewalks, parking lots, and driveways made of asphalt and concrete alike, and the decision to use one or the other is not a question of right or wrong. It’s more a matter of preference or site specifics. Choosing between concrete and asphalt is somewhat like choosing between Volvo or Caterpillar, Ford or GMC, Bobcat or John Deere. None of the choices is bad, but we tend to prefer one over the other.
Concrete paving projects can be in virtually any width and length.
Why Use Concrete?
The Portland Cement Association publishes a list of reasons why concrete pavement is best and some of the points may be appropriate to your particular paving situation. Concrete lasts a long time (40 years or more) and requires minimal maintenance over the years. Thanks to its rigidity, concrete can stay smoother longer than alternatives, and it does not rut. Concrete tends to get stronger as it ages and is less likely to have those washboard stretches you’ve seen on other surfaces. Concrete is an environmentally friendly material, especially when you consider that, when it does need replacing, the old surface can become an integral part of the new project. The entire operation of recycling concrete can be done onsite; that is good news for landfills that don’t need any more highway rubble. Can you use concrete for smaller projects, or must you purchase or rent a huge paving machine? Concrete can be used for small paths and driveways without investing in costly equipment. It will take skill to deliver a smooth surface (and the right tools, all readily available) but that’s just like grading, isn’t it?
Concrete and asphalt are not always competitive solutions for good pavements. Sometimes they work together. One of the growing trends in metropolitan road construction is to pave busy intersections with a mixture of concrete and asphalt pavements. To prevent rutting and washboarding by high volumes of heavy traffic, the core of the intersection is paved with concrete, and asphalt is used farther away from the intersection.
Yukon, OK-based Schwarz Paving Co. Inc., has carved a unique niche in the central part of the state, focusing primarily on metro paving for the Oklahoma Department of Transportation, the Oklahoma City municipal government and surrounding counties, and private developers. Mixed asphalt and concrete intersection paving projects are Schwarz Paving’s bread and butter. “We typically will pave a 300-foot section with concrete and finish with asphalt,” says John Mayfield, general manager for the company. Schwarz Paving used to use traditional slipform pavers for the concrete projects. Many of the intersections would require a combination of 14-foot and 12-foot paving widths, so the contractor would use two pavers, one set at 14 feet, the other at 12 feet. “It would take up to four days to make a width change,” recalls Mayfield. “We would just set and leave the slipform pavers at specific widths.” To meet its paving needs, Schwarz Paving had an arsenal of four slipform pavers set at predetermined widths. This worked well for projects requiring no width changes, but when it came to variable width paving on exit ramps, the contractor would sub out the work. When an intersection flared into a fifth turn lane, the paving crews would need to make an extra pass. The solution came from Terex Roadbuilding, using one Terex SF2204D HVW paver with hydraulic variable width.
“The SF2204C paver was designed to be a time and money saver for contractors like Schwarz, who pave in metro areas where frequent width changes are required,” notes Red Lampkin, district manager for Terex Roadbuilding. The paving operations became much more efficient. Mounted in tandem and modular guillotine side forms, the two paving pans of the SF2204C HVW paver adjust hydraulically in minutes to infinitely variable paving widths, ranging from 8 feet to 20 feet. Each 48-inch-long paving pan is constructed as a water storage vessel that adds 3,340 pounds of weight directly over the concrete. Added to the fast width changes, this Terex paver offers a unique vibrator mounting system. It enables a crewmember to add or remove a vibrator within 10 minutes. As many as 15 individually controlled vibrators can be added to the paver, so the paver delivers uniform density and optimum pavement strengths. Mounted on a telescoping subframe to further simplify width changes, the automatic oscillating float finisher enhances the finish quality. “It is a huge labor savings,” comments Mayfield. “There’s a lot less handwork required, so we use one less man.” This single, hydraulic variable width paver from Terex has replaced all four of the contractor’s traditional midsized slipform pavers.
Basic Concrete Techniques
Slipforming has been mentioned already, and it is surely the most popular method for laying concrete roads today. In slipforming, the mixture is extruded and does not require any side forms; it tends to require less labor, too, The alternative (used often for residential work and all smaller jobs) is fixed-form paving. With fixed-form paving you have metal or wooden forms set along the edges of the paving area, and the mixture is poured into the area thus formed. Workers finish the surface between the fixed forms to produce the desired result. The work can be manual or done by hand-driven or self-propelled paving machines. The equipment for slipforming is expensive, more expensive than the machines for fixed formwork, but slipforming is much faster and less labor intensive. This brings us back to that basic construction question faced by contractors: Which are more expensive in the long run, machines or workers?
As with grading, excavating, and dozing, the one ingredient you cannot ignore in paving is skill. If you find a skilled operator for concrete paving, keep him or her. I know a man locally who is known as the most expert at finishing concrete for driveways, paths, hospital entrances, and similar jobs (jobs where his brain, hands, and arms do most of the work). He is not the most glamorous person, but he is the most expert with his tools, always busy for some contractor.
A consideration that is sometimes ignored by those getting into concrete paving is the location of the nearest concrete plant. It would not be unusual for the nearest plant to be 20 miles away, and that can make a huge difference in the cost of the project, with all the hauling and delivery involved. There is a solution. A contractor whose paving projects tend to be miles from each other and, sometimes, miles from anywhere, should consider acquiring a portable concrete plant. Monroe Bartels, owner of MBI Construction Inc. in Effingham, IL, faced this problem. He had a concrete paving project that was belowground, inside the caverns of an old aggregate quarry. The concrete pour was 1,000,000 square feet, and the temperature and humidity were ideal for the job. But how should the contractor get that amount of concrete to that site, when the nearest source was 20 miles away? A portable plant was the best solution. After considerable research, Bartels chose the Rustler R3 plant from Terex Roadbuilding. The setup design did not require a crane and the optional steel pads meant that there was no need for concrete foundations and the portable plant could be erected into operating position in an hour. “We can have the whole plant operation ready to go in about two to three hours,” comments Bartels. His company typically moves the Rustler R3 for jobs in the 5,000-cubic-yard-and-higher range, but it has been used for jobs as small as 2,000 cubic yards. The plant can produce up to 160 cubic yards per hour.
An integral part of delivering concrete to its final site can be the discharge truck; its role and performance are critical to project success. Less than a year ago Terex Roadbuilding introduced the FD4000 front-discharge mixer. There are two engine options, a Detroit Diesel/MTU and Cummins, and both rely on Selective Catalytic Reduction (SCR) to treat post-diesel particulate filter (DPF) exhaust. A 5-gallon tank positioned near the rear of the mixer trucks stores the system’s diesel exhaust fluid (DEF), which, depending on truck workload, averages to 3% of diesel fuel consumption. All the new Terex front-discharge mixers have an electronic control module that automatically senses whether or not the truck is carrying a load of concrete. This drives the new load-based shift scheduling found exclusively on Terex front-discharge mixers; it matches the shift patterns to the truck’s load for better performance and enhanced fuel economy. The four-axle FD4000 front-discharge mixer features an 11-cubic-yard drum with a 6-inch-wide discharge opening and a durable AR230 Brinell shell.There are good components available (it seems feeble to call them accessories) for every concrete paving system you would like to incorporate into your existing business. The manufacturers of these components, from big pavers to production plants to small trowels, have years of reliable service for contractors, and you could not do better than contact them for the technical details of operations and advice on how to schedule equipment and deliveries. Naturally, each manufacturer prefers its own equipment but you can learn some impartial, valuable points about how to make concrete another profit center for your business.