Vol. 31, No. 2

GOMACO World is published by GOMACO Corporation to inform readers of applied constructiontechnology utilizing GOMACO equipment as well as innovations and concerns in the constructionindustry throughout the world. All rights reserved. The contents of this publication may not bereproduced either in whole or in part without the consent of copyright owner. Printed in U.S.A. © 2003 GOMACO Corporation (09 SP). All stories written by the editor unless otherwise noted.

Address all communications to GOMACO World Editor. If you do not receive GOMACO World,and would like a complimentary subscription, please contact GOMACO Corporation, PO Box 151, Ida Grove, IA, 51445, USA, 712-364-3347 or e-mail bwonder@gomaco.com.

Vol. 31, No. 2 GOMACO

President and CEO Gary L. Godbersen

Vice PresidentsWorldwide Sales and Marketing

Carl V. CarperAccounting Sharon K. Godbersen

Administration & Finance Richard E. SmithEngineering & Service Dwayne Salmon

Sales United States and CanadaSales Manager Bob Leonard

Sales Coordinator Brad ZobelAssistant Sales Coordinator Mike Leinbaugh

United States and CanadaDistrict Managers

Brad Barkema – N.CentralKent Godbersen – CentralJim Hayward – Western

Kendall Kelly – S.W.Vinnie Miller – S.E.Len Rettinger – N.E.

Service DepartmentManager Dennis Ernst

Assistant Manager Joe Hewitt

Parts Manager John KallinParts Desk Dan Ellerbusch,

Jeff Stevenson, & Dean O’Tool

Plant Manager Grant Godbersen

International SalesDirector Bryan Schwartzkopf

Coordinator Randy Bean

International Regional ManagersJoseph Mollard – Latin America

Tim Nash – Asia Pacific

GOMACO International Ltd.Director of Sales & Marketing

Rory Keogh

GOMACO University Training CenterDirector Dennis Clausen

Assistant Director Rod Schneider

GOMACO World is produced by theGOMACO Advertising Department.

Manager Randy BachMarketing Coordinator Micki RettingerGOMACO World Editor Kelly Krueger

Director of Sales Support Gayle HarrisonCommunications Specialist Thomas R. GrellCommunications Specialist Bobbi L. WonderAdvertising Coordinator Carrie J. Odgaard

Photo Lab Don Poggensee

Color Separation by House of Graphics

Please visit our Web site at http://www.gomaco.com GOMACO World magazine at http://www.gomaco.com/gomacoworldGOMACO World Editor Kelly Krueger at kkrueger@gomaco.com

9 12 16 18

3 OPERATION ENDURING FREEDOM– The RED HORSE Squadron (Cover photo by Ken Tippie HW-030305 D17)

9 CHRIS BUCHANAN EXPLAINS STRINGLESS SIDEWALK– Buchanan & Sons Inc.

12 EARNING BONUS WITH AN IDBI ON HIGHWAY 81– Werner Construction Company

16 GT-3600 OPENS DOORS FOR A HANDFORMING EXPERT– Hipskind Concrete Corporation

18 GRADE TRIMMERS AND MOTOR GRADERS– An Interview with Ken Kelly

22 ACCURACY AND VERSATILITY OF GOMACO TRIMMERSDennis Clausen, Director of Training

23 AROUND THE WORLD

3

The men and women in the REDHORSE Squadron of the United StatesAir Force are called upon to completeprojects all over the globe. Often timesthey are the first unit in and will be thelast ones out. They are self-sufficientand have all they need when theytravel, including carpenters, medics,and cooks. Sometimes their projects arecompleted under enemy fire. It is theultimate deadline pressure any buildercan face.

RED HORSE is an acronym whichstands for Rapid Engineer DeployableHeavy Operational Repair SquadronEngineer. The 823rd RED HORSESquadron is based out of Hurlburt Field,Florida, and is a heavy engineeringconstruction unit. Their latest overseasproject took them to the deserts ofOman, a small country bordering SaudiArabia and the Arabian Sea in theMiddle East.

“As it turns out, this $27 million, 47 acre (19 ha) project, which covered anarea equal to 36 football fields, was thelargest ever constructed by REDHORSE,” Major Mark Mittler, on-sitecommander in Oman, said.

A major part of the project includedconcrete slipform paving.

“We were tasked to deploy to thearea of operations (AOR) and constructan aircraft parking ramp with adjoiningtaxiway and arm/de-arm pads,” SeniorMaster Sergeant Ron Westerfield said.“There were only four men on our crew

who had slipform paving experience.”The United States Air Force and the

RED HORSE Squadron not only neededthe paving equipment in a short amountof time, they needed a company thatcould train their men and teach themthe concepts of concrete slipformpaving. GOMACO stepped up to thechallenge.

Weeks after the orders were placedfor two complete paving trainsconsisting of PS-2600 placer/spreaders,GHP-2800 pavers with Auto-Floats®, andT/C-400 texture/cure machines, theequipment was ready for shipment. Thefastest way to get six pieces of concrete-finishing equipment from Ida Grove,Iowa, to the deserts of Oman would beby air.

The Antonov-124-100 Russian cargoplane, one of the world’s largestcommercial cargo airplanes availabletoday, would transport the equipment to

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“Can Do,Will Do,Have Done”– Motto of the

RED HORSE SQUADRON

Operation Enduring Freedom

When an Air Force person re-enlists, it’s a special occasion and steps are taken to makeit memorable. In this case, RED HORSE Master Sergeant Thomas Mattingly (right) is

administered the oath by Captain Kevin Merritt on top of the GHP-2800 paver.

A view from inside the Antonov as theGHP-2800 paver is loaded at Eppley Airfieldin Omaha, Nebraska.

Members of the Squadron unloadthe equipment in Oman.

One complete paving train fits insidethe Antonov with room to spare.

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Oman in two separate shipments. Thefirst Antonov shipment consisting of onefull paving train left from EppleyAirfield in Omaha, Nebraska, onDecember 26, 2002. A second Antonov-124-100 flew out with the last pavingtrain January 9, 2003.

With the manufacturingof the equipment nearcompletion and shipmentpending, the members of the REDHORSE Squadron still needed training.A special week-long paving school atGOMACO University was scheduled.

Both classroom lectures and hands-ontraining in the University’s shop helpedprepare the Squadron for their mission.

“We have experience with largerprojects but not with slipformingequipment,” SMSgt. Westerfieldexplained. “The hospitality shown to uswhile we attended classes was an eye-opener and the training at GOMACOUniversity was a tremendous asset toour being able to operate the

equipment.”Work on the project began in

October 2002. Westerfield and the

4

RED HORSE Squadron arrived in earlyJanuary 2003 and began preparations forpaving.

“In the desert, there is a variety ofsubgrade conditions,” SMSgt.Westerfield said. “You can have sandthat is as fine as baby powder and isdifficult to level and remove or youhave ground that is so compacted thatyou have to use an excavator andjackhammer to remove it.”

In the desert conditions, just settingstringline proved to be a difficult task.

“The stringline stakes were set in six inches (152 mm) of base material, aswell as in some of the most compactedsoil. It was pretty difficult at times, butwhen you use jackhammers with aircompressors to drive the stakes it makesit easier,” SMSgt. Westerfield explained.“One of the most difficult things wasdealing with the wind. There were times when there would be a constant30 mph (48 km/hr) wind with 40 mph(64 km/hr) gusts causing sandstormsand making it difficult to set thestringline. We had a great crew leader inTechnical Sergeant George Yepes whoattended GOMACO University and hadsome previous experience.”

The total size of the new concreteparking ramp, taxiway and arm/de-armpads was 980 feet (299 m) wide by 2100 feet (640 m) long. The entire projectsloped 0.5 percent or 10 feet (3.05 m)

Paving passes were 980 feet (299 m) longand 20 feet (6.1 m) wide with the GHP-2800. Secret Training at the “U”

During the second weekof December 2002, a specialclass was held at GOMACOUniversity. Fifteen membersof the RED HORSE Squadrontraveled from Hurlburt Field,Florida, to Ida Grove, Iowa,for the week-long class.

The class provided theSquadron members with bothclassroom lectures andhands-on learning in theshop about the fundamentalsof slipform paving and theoperation of GOMACOequipment.

Attending the class were,front row from left,GOMACO Serviceman KenTippie, TSgt. Ralph Evans,SSgt. Jeremy Isaac, A1C TonyMoreno, TSgt. George Yepes,SSgt. Cresenciano Silva, TSgt.Jerry Girvan, TSgt. StevenStanford, SrA Justin Hoesseland GOMACO ServicemanRic Moser. Back row fromleft, MSgt. Thomas Mattingly,TSgt. William Lipscomb,SSgt. Eric Sexton, TSgt.Michael Maccarone, SMSgt.Ron Westerfield, TSgt. JasonBaker, and TSgt. DaleColeman.

The class learns the finer points of operating theGOMACO Controller on the GHP-2800 paver.

A group photo of the Squadron and their instructors.

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6 Two T/C-400s follow the paver dragging burlap and spraying the curing compound on the 16 inch (406 mm) thick slab.

across the length of the concrete.The GHP-2800s paved 20 feet

(6.1 m) wide lanes, each 16 inches (406 mm) thick.

“The GHP-2800s did anoutstanding job of putting downconcrete,” SMSgt. Westerfield said.“There were very few problems andwe could tell that the people whobuilt them take great pride in whatthey do.”

A mobile batch plant capable ofproducing 288 yd3 (220 m3) of concreteper hour was on-site. Dump truckswere leased from a local company and each had the capacity to deliver11.8 yd3 (9 m3) of concrete per truck tothe paving site.

The concrete mix design had ahigh cement content with .75 inch (19 mm) maximum aggregate size anda high percentage of manufactured fines0.12 inch (3 mm) or smaller. Waterreducers and plasticizers were addedbecause of the desert environment andwater restrictions. Entrained air in the mix ranged between four to fivepercent. Slump averaged between one to two inches (25 to 51 mm).

“There were many variables andissues that we encountered every nightthat affected production, but on theaverage, we would pave a 980 foot

(299 m) lane in four hours, about 221 yd3

(169 m3) an hour,” SMSgt. Westerfieldsaid. “There would be times when we’dpush the plant to its limits at about 288 yd3 (220 m3) an hour.”

Several of the factors influencingproduction included hot daytime

temperatures, material deliveries tothe concrete plant which had limitedstorage in the cement silos, andlearning the slipforming process onthe go. They also had to deal withsome substandard materials, watershortages, language barriers whenworking with the locals and longsupply lines.

To combat the hot desert conditionswith temperatures exceeding 100º F(38 ºC), 80 percent of the project waspaved at night. Night-time pavingsolved some problems but it alsocreated other complications.

“The most difficult part of thisproject was getting the plant toproduce a consistent mix, not that itwas all the plant’s fault,” SMSgt.Westerfield explained. “We wouldstart paving at 3 or 4 p.m. while the

temperatures were still pretty hot, butby 8 p.m. the temperatures had droppedto where we needed a drier mix.”

Every other lane was slipformedwith stringline. Then, the Squadronwould come back and pour the fill-in

Eighty percent of the project was slipformed at night to combat the hot desert temperatures that surpassed 100º F (38º C) during the day.

A map of the Middle East region illustratesOman’s strategic location for the war.

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lanes using the lock to grade feature.Paving locked to grade and the Auto-Float® attachment on the GHP-2800pavers saved time.

“The Auto-Float® was essential to theproper completion of our project,”SMSgt. Westerfield said. “With ourlimited manpower, we didn’t haveenough people to actually bull float andbroom the entire project. Even if we did,it wouldn’t have been very efficient oreffective to do.

“We tried to keep the hand-finishingto a minimum. Joints were cut at 20 foot(6.1 m) spacings equally throughout the project. It made for a total of 210,000 linear feet (64,008 m) of sawcuts.”

The T/C-400 texture/cure machinesdrug burlap and sprayed on a curingcompound to complete the pavingprocess.

“All of the GOMACO machinesperformed outstandingly and definitelymet our expectations,” SMSgt.Westerfield said. “This was a majorundertaking for us and we do a widevariety of construction tasks and not justconcrete. If you have to go to the desertto construct anything... be patient.Things don’t happen as quickly overthere.

“This project was in support ofOperation ENDURING FREEDOM anddirectly contributed to the liberation of

Volunteering for the MissionWord spread quickly

around GOMACOCorporation... the Air Forcewas buying two of ourpaving trains for a classifiedproject in the deserts ofOman. The RED HORSESquadron would be doing theslipforming and theirexperience was very limited.The GOMACO ServiceDepartment would have tosend two of their men to thedesert to train and workhands-on with the Squadronfor the first month of paving.

Two servicemen steppedforward and volunteered forduty, Ric Moser and KenTippie. Ric even had theopportunity to escort the firstpaving train shipment andflew aboard the Antonov withits all Russian crew.

“There was a lot to learnand with Ric and Ken there toteach us the entire spectrum,it went very well,” SMSgt.Westerfield said. “Ric andKen were the best. Therewould have been no way thatwe could have completed thisproject without theirexpertise.”

Ric Moser (right) offers some paving advice to amember of the RED HORSE Squadron in Oman.

Ken Tippie checks for edge slump.

Fill-in lanes were slipformed with the paverlocked to grade and eliminated stringline.

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The transition from daylight to night-time paving created challenges for the batch plant because of the difference in temperature.

Iraq. The men and women ofRED HORSE that were involvedin the completion of this projectgave their all and sacrificed agreat deal for their country. Itwouldn’t have been possiblewithout the people of IdaGrove, Iowa, and the workers atGOMACO. They did a fantasticjob.”

“This inspiring project wasindeed a win-win situation forGOMACO and the U.S. AirForce,” Colonel BenjaminAnderson, commander of theRED HORSE Squadron, said.“As a result of unparalledteamwork and dedication, ourcombined team achieved truesuccess. Undeniably, thisteamwork resulted in the fast-track completion of the largestand most challenging projectever constructed in the 38 yearhistory of RED HORSE.”

Seven months after

beginning work, the concretepaving was finished and the airbase was operational. The REDHORSE Squadron returned totheir home base at HurlburtField more versatile than everbefore. Their Squadron motto,“Can Do, Will Do, Have Done,”now includes concrete slipformpaving.

Editor’s Note: GOMACOCorporation is proud of the role weplayed with helping the REDHORSE Squadron achieve theirgoals. We’ve been waiting sinceJanuary to share their story withour GOMACO World readers, butwe made a promise to them thatwe’d wait until now. We didn’twant to do anything to jeopardizethe safety of our troops in the field.It is with great pride that wehelped them become concreteslipform professionals and are ableto share their story with you.

“This project was in support of Operation ENDURING FREEDOM anddirectly contributed to the liberation of Iraq.The men and women of REDHORSE that were involved in the completion of this project gave their alland sacrificed a great deal for their country,” SMSgt.Westerfield said. “Itwouldn’t have been possible without the people of Ida Grove, Iowa, and theworkers at GOMACO.They did a fantastic job.”

Workers were limited on the project and the Auto-Float® cutthe number needed for finishing work behind the paver.

Dump trucks with a 11.8 yd3 (9 m3) capacity carried concretefrom the mobile batch plant to the paver.

The new sign above the shop door at GOMACO University.

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Buchanan and Sons Inc. has beenslipforming curb and gutter andsidewalk with their GT-3600 since 1999.Chris, the youngest of the Buchanansons, is the company’s vice president andGT-3600 operator. Of all the differentprofiles they slipform, sidewalk is Chris’favorite, claiming that “it just lookspretty.”

They slipformed all of their sidewalkthe traditional way, setting theirstringline and trimming as they poured.Then they bid and won a project in SawMills, North Carolina, requiring them toslipform approximately 3000 feet (914 m)of curb and gutter. With the curb andgutter in place, they would then have tocome back and scab on a five foot (1.5 m)wide sidewalk onto the newlyslipformed curb and gutter.

The first step was preparing thegrade. Equipment was brought in tocreate the required soil-cement treatedsubgrade. Once the grade was ready, theGT-3600 was moved in.

A North Carolina Department ofTransportation (NCDOT) standard30 inch (762 mm) curb and gutter witha three inch (76 mm) radius on the faceand flow line was slipformed first.

The sidewalk could not be trimmedand poured simultaneously becauseBuchanan’s do not have a left-side

trimmerhead discharge on their machine.Buchanan instead brought in a tractorwith a box blade.

“The trimmer would have dischargedtowards the curb so we had to use ourtractor instead,” Buchanan explained.“We have two guys with rods and levelschecking grade. My brother, Carl Jr., ison his tractor with a five foot (1.5 m) boxblade. We get our angle right and bladethrough, gauging off the curb to geteverything to grade.”

The project had some challengingaspects with tight clearances because ofutility poles and trying to set stringlineto match the existing curb and gutter.Buchanan called GOMACO with an idea.

“It’s about impossible to setstringline and pour to the back of curb,”Buchanan said. “I had read other articlesabout guys sensoring off their existingcurb and pouring their sidewalk thatway. I figured I should be able to do itwith my machine, too.”

The needed parts and sensor bracketswere shipped to North Carolina. A weekafter pouring the curb and gutter,slipforming the scab-on sidewalk began.The GT-3600 needed a quick moldchange and some reconfiguration of theleg positioning and it was ready to go.

“It doesn’t take very long to switchto the sidewalk mold. You just pull the

9

Chris Buchanan ExplainsStringless Sidewalk

A view from the operator’s platformlooking down as the sensor rolls acrossthe top of a catch basin. The photo belowshows the finished sidewalk.

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two drawbar pins, unhook theholddown, pick up off the mold, driveover the sidewalk mold and set downon it,” Buchanan explained. “It tookme a while to figure out how I wantedto set up the machine. That’s where theadjustable legs are great. I can movethem where they need to be.”

Buchanan was concerned the trackswould mark on his newly poured curband gutter. With the GT-3600’s All-Track Positioning (ATP), he was able tosideshift the back leg over so it wasrunning on the asphalt road, straddlingthe new curb and gutter.

“The first 50 feet (15.2 m) didn’tpour very good because I didn’t have itadjusted right,” Buchanan said. “Mybrother wanted to park the thing andstart handforming. I told him not tobail out yet and to give me a few moreminutes to readjust some things. Afterthat, we poured 200 feet (61 m) moreand he was very happy with it saying‘I’m glad I thought of this, it workspretty good.’”

The sidewalk is five feet (1.5 m)wide and four inches (102 mm) thick.The concrete is a NCDOT 4500 psi (31 MPa) standard mix design for boththe sidewalk and curb and gutter.

Slump averaged three inches (76 mm)for the sidewalk and two to 2.5 inches(51 to 64 mm) for the curb and gutter.

Perhaps the most challengingaspect of the project was getting thesensors set and the wands at theproper angle.

Buchanan had to reverse thedirection of his sensors so he couldpull the grade skis across the curbinstead of pushing them along. Bypulling the skis, it helped keep themfrom catching on anything and gettingpushed back into the sensor anddamaging it. The tube is still

positioned in front of the sensor andthe GT-3600’s controller stays in thepush operating position.

He also had to run the wand at a45 degree downward angle instead ofthe normal horizontal position. If thewand had been kept horizontal, itwould have been flush with the bottomof the sensor and the sensor wouldhave been hitting the curb.

“I had the front sensor in line withthe front of the mold and the rearsensors in line with the back of themold,” Buchanan explained. “The setup kept the front of the mold fromcatching. It looked awkward at timesbecause the front of the machine wouldbe high, but at the mold, it wasperfect.”

Another trick Buchanan used wasslipping a round, wooden ball on theend of the steering wand. The ball keptthe wand from falling into andcatching on the joints in the curb.

“It just rolls round and round anddoesn’t fall into any holes,“ Buchanansaid. “I even rolled it over the top of acatch basin with no problems. Thesidewalk went right to the back of it,the finishers edged it and we kept ongoing. I knew if we did the catch basin

The trimmerhead was sideshifted and vertically lifted out of theway while the sidewalk was slipformed.

Buchanans slipformed the curb and gutter in the first phase of theproject. A week after completing it, they came back with their sidewalkmold and tackled their stringless challenge.

The aggregate base course is leveled out witha tractor and box blade to form the grade.

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we’d be showing off, because mostpeople just leave them. They won’teven tie into them when they’repouring their curb. I think it’saggravating not to and then have to goback and do them by hand.”

Very little finishing work had to bedone to the sidewalk because of theconcrete mix design and the set up andfinishing capabilities of the GT-3600.The sidewalk was edged along theexpansion joint separating it from thecurb, bull floated, and joints were cutin. Control joints were saw cut everyfive feet (1.5 m) and expansion jointswere every 50 feet (15.2 m).

“A lot of the sidewalk didn’t evenhave to be edged and I think that had alot to do with the mix,” Buchanan said.“I had the mold so close to the back ofthe curb that it was actually rubbingagainst the expansion joint. There wasnothing that could physically blow out.

“The big trick to it was that I didn’tlock the mold down. The reason I leftmy mold loose is when I set the molddown, I could push it over two or threeinches (51 to 76 mm), set it down allthe way, and then set it into the curb. Iwasn’t trying to push in or out while Iwas pouring, only when I was setting

up each time.”The 3000 feet (914 m) of sidewalk

was slipformed in three days. The best production was approximately1100 feet (335 m) slipformed during aseven hour day.

“We’re the only ones around herethat do this and it’s going to be one ofour selling points,” Buchanan added.“The GT-3600 has allowed us to dosomething we’ve been doing all along,concrete work, at such a fast rate. It’sbeen opening doors to do moregrading, more storm drainage andother aspects of the project, not justhandforming 3000 feet (914 mm) ofcurb and sidewalk.”

Because of the GT-3600 and theBuchanans’ own work ethic and desireto produce a quality product, thecompany is growing at a phenomenalrate.

“We are one of the fastest growingcompanies in western North Carolinaand the GOMACO curb machine iswhat got it all started,” Buchanan said.“We just got a project where we werepreselected and were the onlycontractor allowed to bid on it due toour honesty, quality of work and otherfactors like that.”

With all the success they’reexperiencing, the company hasn’tforgotten their roots and the lessonsCarl Buchanan, the company’s founder,taught them.

“Our dad taught us to take pride inour work and take the time to do thejob right,” Buchanan explained. “Thebest advice I can give is buy aGOMACO. I know I wouldn’t bepleased with anything else because Iwouldn’t be able to do the things I’mdoing now. A lot of my competition arerunning a locally built product, but me,I’m running a real machine.”

The GT-3600’s All-Track Positioning (ATP) allowed Buchanan theoption to move his back leg over far enough so the track wasn’trunning on the newly slipformed curb and gutter.

Close-up photographs of the sensors illustrate Buchanan’s uniqueset up and the exact positioning of the sensors and wands.

The best advice I can giveis buy a GOMACO. I knowI wouldn’t be pleased withanything else because Iwouldn’t be able to do thethings I’m doing now,”Buchanan explained.

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“There’s thget a good stringline, sstringline,” W“Stringline important t

Earning Bonus with anIDBI on Highway 81

Photo by Randy Bach HW-060314 D29

Highway 81 has been Werner ConstructionCompany’s mission for the last 10 years. Theyhave been slipforming their way south onHighway 81 in southeastern Nebraska. Since1997, their goal for the highway has been toturn 36 miles (58 km) of the two-lane highwayinto a four-lane roadway leading to theNebraska/Kansas border.

In 2001, the GOMACO owners decided toupgrade their paver to a GHP-2800 equippedwith an In-The-Pan Dowel Bar Inserter (IDBI).

“We wanted the IDBI mainly because ofproduction, labor and trimming,” RobWemhoff, project manager, said. “Productionand labor-wise, it saves us between five andsix people that would usually be working onthe dowel basket crew. Trimming-wise, ifyou’re behind on your trimming and you stillhave to set dowel baskets, you need a day inbetween trimming and paving. With the IDBI,essentially you can follow the trimmers. Youcan be paving a quarter mile behind thetrimmers andhave twooperations goingat the sametime.”

Werner’s jobson Highway 81are any projectmanager’s dreamjob. Traffic runson the existingtwo-lanes whilethe new lanes areconstructed. Theproject is openand accessibleand a portablebatch plantsupplies concretewithout a longhaul time.Between sevenand 13 truckshaul concrete tothe job site at asteady pace.

“This is good

work,” Wemhoff said. “We’re still dealing withtraffic, but it’s nothing like city or interstatework. I like building work like this and it’s funto do new work. We can be a lot moreproductive.”

They are in the process of completing thelast contracts on the highway, two separatejobs connecting Fairmont to Geneva andGeneva to Strang. The biggest problem they’vefaced is Mother Nature and an extremely wetNebraska spring. It’s affected not only theconcrete paving, but base preparation, too.

“Geneva has a lime-treated subgrade witha crushed concrete or millings base course.Strang has a fly-ash treated subgrade withcrushed concrete base,” Wemhoff said. “Thecrushed concrete base at Strang is prettyforgiving if it gets rained on. The millingsbase, if that gets a couple of inches of rain on

it, we might haveto tear it back upand start over.We’ve preppednon-treatedsubgrade three orfour times, it getsrained on, andwe start all overagain.”

Despite therain, Wernercompleted thetwo contractsahead ofschedule.

“Geneva northand south startedApril 2, 2001,with 320 workingdays allowed,”Wemhoff said.“Strang northand south startedon November 5,2001, with 200working days.

Werner Construction Company has 36 miles (58 km) of newroadway on Highway 81 in Nebraska. They are using theirGHP-2800 paver with IDBI to slipform the 29.5 foot (9 m) wide,10 inch (254 mm) thick concrete road.

ree things toride...tringline,Wemhoff said.is the mosthing.”

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The map of Nebraska illustrates the scopeof Werner’s projects on Highway 81.

Werner operates two 9500s with 18.8 feet (5.7 m) wide trimmerheadsto trim the subgrade and grade. They are run off a dual-stringlinewhich Werner feels increases the accuracy of the cut.

Both jobs will have five to 10 days left over when they’recompleted.”

Their production has been averaging 3000 yd3 (2294 m3)per day with some days exceeding 3500 yd3 (2676 m3).Werner’s rideability has been excellent, also. The state ofNebraska is paying them a three to four percent or higherincentive bonus on these last two jobs on Highway 81.

Werner’s paving process begins with grade preparationand two 9500 trimmers. The 9500s are each equipped with18.8 feet (5.7 m) wide trimmerheads for maximum cuttingwidth. The 9500s run in tandem, one in front of the other,with the back one trimming in the opposite lane than thefirst. The first 9500 windrows the trimmed material to thetrailing machine and that trimmer discharges into the haultrucks. They run off a dual-stringline with telescopingextended sensor arms reaching over to the stringline.

“We have the longest trimmerheads made so we can runthem side by side,” Duane Childs, job superintendent,explained. “We’ll trim subgrade half a day, back up, lay thebase and then trim the base, and just keep a processionbetween them and the paver. I think the dual-stringlinesetup is more accurate and increases our production. We cantrim a mile (1.6 km) per day.”

The GHP-2800 with IDBI follows closely behind the

9500s. It is paving the new roadway and shoulders 29.5 feet(9 m) wide and 10 inches (254 mm) thick. The IDBI inserts26 bars, 12 inches (305 mm) apart, across the width of theslab. The 1.5 inch (38 mm) bars are inserted into the slabevery 16.5 feet (5 m).

A rear-mounted bar inserter places a #5 bar every 24 inches (610 mm) into the center line of the two lanes. The bar inserter is controlled by the IDBI’s computer.

“The IDBI wasn’t a hard process to learn,” Childs said.“We have Clyde Stamper, he’s our paver operator, and he’spretty good on a computer. When we first got our machine,service representatives from GOMACO and Tim Jindra,from our distributor Murphy Tractor, came out and helped

Wemhoff supervises the trimming operation. A powered Spanit® work bridge drags burlap. Spray cure is applied to the new roadway.

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us with set up. Tom Bell helped us with start up and taughtus how to run the IDBI computer. They all took pretty goodcare of us.”

Sections of the new roadway were saw cut to check theaccuracy of the IDBI’s bar placement. All of the bars wereaccurate and well within the state specifications.

“The GHP-2800 with IDBI does a nice job,” Childsadded. “They run a profilograph with the two-tenthsblanking band to check our ride and we usually get bonuspay on all of it.

“To get bonus pay, you have to make sure your machineis set up and lined up right. We use the two-quarter trick.You run your stringline across and make everything flat.

Then, you take two quarters and put them together andthat’s how much draft you put in your pan just to feed theback pan.”

The GHP-2800 is also equipped with an Auto-Float® toapply a finish to the new roadway. The T/C-600 texture/cure machine follows the paver applying a longitudinal tineand spray cure.

“There’s three things to get a good ride... stringline,stringline, stringline,” Wemhoff said. “Stringline is the mostimportant thing. Track line and finishing are important, too.You’ve got to run on a trimmed grade and your track linehas to be hard. You can’t have any soft spots in it at all.

“With finishing, the state wants us to check the slabwith a straight edge. When it comes out of the paver, it’sfine and you just don’t want to mess up the slab whileyou’re straight edging it.”

The last two jobs of Werner’s project on Highway 81 arealmost complete. They will have finished the $26 millionproject early and earned bonus on the 418,610 yd2

(350,000 m2) of mainline concrete pavement that they haveslipformed with their GHP-2800 with IDBI.

Their next project takes them to Highway 26 slipforminga new roadway between Scottsbluff and Minatare,Nebraska.

“We’re the subcontractor on the project and all we haveto do is pave seven miles (11.3 km) of 30 foot (9.1 m)concrete on a new grade,” Wemhoff said. “It’s going to be areally nice job.”

The accuracy of the IDBI was tested in several saw cut slabs. All of the bars were accurate and within the state’s specifications.

The IDBI inserts the bars into the slab. The T/C-600 applies the longitudinal tine. Final rideability results were excellent.

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Hipskind ConcreteCorporation in Fort Wayne,Indiana, is a company with avaried past. In the 1970s, theyspecialized mostly in asphaltpaving but did a little bit ofeverything to stay competitive.It was during the ‘70s thatPatrick Hipskind, the currentowner of Hipskind Concrete,started working for his fatherand taking care of the concretework.

The ‘70s is also whenHipskind first tried slipformingcurb and gutter with a tow-behindform. Their first attempts didn’t proveto be successful.

“Ninety percent of what we didwas reconstruction where you removeand replace the existing,” Hipskindexplained. “With the old pavementgrades and the rest of it, the machinejust didn’t adjust fast enough to carry a decent grade.”

Slipforming was abandoned andHipskind returned to their tried andtrue method of handforming all oftheir curb and gutter.

In the ‘90s, Hipskind decided itwas time for a total career change. Hepacked up his family and headed outto the Yukon Territory of Canada.

“I just got fed up with theheadaches and went to the YukonTerritories and mined gold for fouryears,” Hipskind said. “We took out$3.5 million in gold but it cost me $3.8 million to do it and that wasn’t agood thing.”

He returned to Indiana and wentback to concrete work, mainlyhandforming curb and gutter.

It wasn’t until 2002 that HipskindConcrete would once again reinventitself. Handforming would be replacedby slipforming when Hipskindpurchased a GT-3600 curb and guttermachine from GOMACO.

“Last spring we had a couple ofreally good hands just up and walkwithout any notice at all,” Hipskindexplained. “We had a pretty good load

on the books at the time and there wassome work coming up that I knew wecould be competitive with if we couldget the curb in faster and increase ourproduction.

“I just called Kent Godbersen,GOMACO’s Midwest DistrictRepresentative, on the phone andasked him if he had one in stock.Never flew out to Ida Grove, never rana machine, just jumped in with bothfeet...”

The majority of Hipskind’s projectsare reconstruction in residentialneighborhoods with existing trees,utilities and tight-clearance conditions.They also face the challenge ofscabbing on to the existing roadwayand essentially pouring their curb andgutter in a hole. Tight clearances andbelow the grade slipforming are someof the challenges the GT-3600 wasdesigned for.

“Seldom are we in the open gradewhere you’re wide open and there’s notrees or any of the rest of it to getaround. Because of those reasons, weliked the smaller, tighter design of theGT-3600,” Hipskind said. “We use theextra steering features a lot when we’repicking up, moving off, getting aroundin the neighborhood and it worksreally well. We go around a lot of treeswhere we have to pull up, move over,shift a little bit here and there and it allworks just like they planned. It saves alot of back turning, twisting and tight-clearance with the rehab work.”

The majority of the curband gutter Hipskind slipformsis either 24 inch (610 mm) rollcurb, 20 inch (508 mm) stand-up or a 24 inch (610 mm)chairback that has to havecontinuous steel reinforcing.The profile they slipformdepends on the existing curbin the neighborhood they’rereconstructing.

“We’re dropping andchanging the mold all thetime,” Hipskind said. “It’s nota tough process and it goes

real quick. One man can do it. Thesystem on the GT-3600 works reallygood... drop the profile, replace it, lockit in place, and she’s ready to go.”

Their concrete mix design is astandard Indiana Department ofTransportation #8 mix with slumpaveraging 1.5 inches (38 mm).

Depending on the project size andthe number of driveways, the crew willaverage between five to six men. Inresidential neighborhoods, drivewayswill be every 50 to 100 feet (15.2 to 30.5 m). The driveway cutoutattachment saves both time andconcrete.

“It saves us a lot of grief and a lotof concrete because we don’t have toshovel half of it off again,” Hipskindsaid.

Finishing work, according toHipskind is almost nonexistent as long as a quality mix is fed into theGT-3600. It was a hard lesson for thenew slipforming crew to learn.

“To run a curb machine, you haveto know what concrete looks like andwhat it’s supposed to look like,”Hipskind explained. “It helps when theoperator has been around it longenough to know when the concrete’snot coming out of the truck right. It’sall in getting the mix and theconsistency right to eliminate thefinishing. When we first started,nobody had worked behind a machinebefore and they wanted to get on thecurb and start rubbing it. They were

GT-3600 Opens Doors for aHandforming Expert

Hipskind Concrete has more than tripled their curb and gutterproduction since adding a GT-3600 to their operation last year.

Photos by Ed Lampe CG-050203 D14

Steel reinforcing (right) is manually fed into the mold on the GT-3600. Thesteel is mandatory in Indiana’s 24 inch (610 mm) chairback curb and gutter.

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just making themselves more work. Nowthey’ve learned to leave it alone, just touchit up a bit, and broom it. It was a biglearning curve for the boys behind themachine.”

Production continues to increase onevery project. By the end of the season,they were slipforming 3200 feet (975 m) ofcurb and gutter in a day, more then triplingwhat they averaged while handforming.

“We’re used to doing hard-wayconstruction, but by the end of the season,my boys were standing with their hands ontheir hips thinking this machine is the onlyway to go,” Hipskind said. “It’s all readyopened up a few more doors for us, justwith the workload we did last year and theversatility of it. It makes us a lot moreversatile. Things go a whole lot faster andproduction is a whole lot quicker.”

Hipskind is now into his second seasonof slipform paving. His advice for otherpeople considering a curb and guttermachine is simple.

“If you want the production, if youwant to do it right, if you want to do itfast, and if you want to drive the Cadillac,you better order the GT-3600,” Hipskindsaid. “There’s only one top of the line and Ilike to do things right so I don’t have to doit again. In concrete, doing it once is theonly way to go.”

Finishing work is almost nonexistent with theGT-3600 and Hipskind runs a slipforming crew ofonly five or six men. C

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Cut an Accurate GradeAccurate subgrade requires the proper

settings and adjustments be made on thetrimmer. One of the key items that must beadjusted properly is the relationshipbetween the height of the trimmerwheelteeth and the moldboard.

When the trimmerwheel is adjustedproperly, the tooth marks are slightlyvisible in the compacted subgrade behindthe trimmer (tooth marks may not bevisible in a loose subgrade such as sand)(Photo 1). If the teeth are set too low inrelation to the moldboard, excessive finematerial may be left on the grade (Photo 2). If the teeth are set higher thanthe moldboard, “chunks” of the subgradematerial may be torn out of the grade(Photo 3). If the teeth are too high, it canalso cause high tractive pressure, difficultycontrolling the steering of the machine andproblems maintaining precise gradecontrol on the machine. In most cases, the teeth are set to operate .25 to .375 inch(6 to 10 mm) below the moldboard. Oneway to check for the proper adjustment isto simply observe the grade behind thetrimmer. Another way is to place a 6 x 6 x.375 inch (150 x 150 x 10 mm) plate undereach end of the moldboard (should be onhard surface). The teeth should just touchthe surface that the machine is sitting on.If not, adjust the wheel up or down asnecessary (Photo 4).

One item that affects the relationshipbetween the height of the trimmer wheeland the moldboard is tooth wear. Onearlier machines, the teeth were ahardened casting. This type of toothwould wear down over time, changing therelationship. How long it took for the teethto wear down depended on the type ofmaterial being trimmed. Obviously teethwear was a lot quicker in an abrasivematerial. As the teeth wore down, thetrimmerwheel needed to be lowered to

maintain the relationship. When the teethwore down to the holder, they needed tobe replaced (Photo 5). With new teeth, thetrimmerwheel needed to be raised back upto maintain the relationship with themoldboard. If compensation for toothwear was not made, a poorly finishedsubgrade resulted.

Today’s machines feature a carbide-tipped tooth. These teeth do not wear asfast as the old style, therefore lessadjustment is needed. If the carbide tipbreaks off, the tooth must be replaced.

Another item that will affect thefinished grade is the sensitivity setting ofthe elevation controls. If the sensitivitysetting is not correct, it will causedeviations in the subgrade. If thesensitivity is set too low, it will causegradual “swales” in the finished product.Loose stringline or too much springtension on the sensor wands can alsocause these “swales.” However, if the lineis loose, or the spring tension high, the“swales” will be between the grade stakeswith the grade correct at each stake. If lowsensitivity is causing the “swales,” it willbe random and will not necessarily followthe grade stake spacing. If the sensitivityis set too high, it will cause the machine toover react. Initial grade sensitivity settingfor an Analog system is to turn theadjustment all the way clockwise and then

back a quarter of a turn. Initial grade sensitivity setting on a

Micro system is 4 to 5 indicators showing.Initial grade sensitivity setting on aNetwork system is 12 to 15 indicatorsshowing and the setting is number 12 to15 on the G21 system (Photo 6). The initialslope sensitivity setting on any of thecontrol systems is normally at maximum.Once trimming operations have begun,adjust the sensitivity setting as high aspossible without the machine becomingover sensitive. The sensitivity can be alsoaffected by machine travel speed, rearconveyor position and depth of cut. Adjustthe sensitivity to give the best results.

Saves Time & MaterialNormally a trimmer is used to cut the

final subgrade in preparation for paving.However, it can be used for more.

Consider for example when opengraded base material must be placed onthe subgrade. Normally a motor gradermakes several passes to cut the base priorto applying the base material. If the gradeis not cut close enough with the motorgrader, an excess of material is used(wasted).

For example, if an extra .5 inch (13 mm) of base material is used on aproject that is 24 feet (7.32 m) wide and2700 feet (823 m) in length, over 100 tons(90 Metric Ton) of additional material isrequired. If the blade is used to cut thebase material to final grade, the excess issimply pushed off to the side and wasted.

Now consider the use of the trimmer.It is used to cut the grade to the exactelevation, normally in one pass, prior tothe placing of the base material. After thebase material is in place, the trimmer isused to cut the base material to exactgrade, again in one pass. The open gradedbase is now at the correct thickness andelevation. The excess material can be

Photo #1 – visible tooth marks Photo #2 – excessive fine material on grade Photo #3 – chunks torn out of subgrade

Accuracy and Versatility ofthe GOMACO Trimmers

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Feeding a concrete pump on a bridge deck project.

by Dennis Clausen, Director of Training

windrowed or loaded into haul units to besaved for the next project.

The same example will hold truewhen paving. If the grade cut with themotor grader averages .5 inch (13 mm)low for the same dimensions as above, anextra 100 yd3 (76.5 m3) of concrete will beused (wasted). If the grade cut with themotor grader is consistently high, it willcause a thin slab which may have to beremoved.

Versatility is the Name of the Game

Today’s contractor wants moreversatility in a machine. Therefore, thequestion comes up, “What can I do with atrimmer other than trim grade?” A placingattachment is available for the machine.This attachment is installed in place of thetrimmerhead in just a few short hours.With the placing attachment installed,concrete can be delivered from the centralmix plant in dump or mixer trucks andplaced in front of the paver without thetrucks being on the trimmed grade. Thematerial is dumped into the hopper and isconveyed to the paver in a swift action.Using this procedure allows dowel barbaskets to be preset on the grade in frontof the paver. The operator can control the“head” of concrete in front of the paver bycontrolling the rear placing conveyor.

A contractor in St. Louis, Missouri,uses his 9500 for more than just placingconcrete in front of his pavers. Concrete isdelivered to most of his jobs by dumptruck from central mix, even hand pours.He runs the concrete through the 9500 andaccurately places the material in the forms.He also dumps concrete into the 9500 andsupplies it to his Commander III whenpouring barrier/ parapet walls and even

when pouring curb and gutter.A contractor in California uses a

trimmer to cut the grade for slab-on-gradehouse construction. The grade for theconcrete slab the house is to be built onmust be within specs. Another contractorsaid he could cut the grade quicker with amotor grader. A housing developmentneeded grade cut for approximately 20new homes. The contractor with thetrimmer cut 10 and the contractor with theblade cut the other 10. The motor graderdid indeed cut his 10 in less time. Theinspectors then showed up to inspect thegrade. All 10 done with the trimmer werewithin spec, while more than half of thosedone with the grader were out of spec andrequired more work.

Other contractors that pour a lot ofmonolithic curb, gutter and sidewalkneeded a better way to cut the roughgrade. They equipped their trimmer with amonolithic trimmerhead and cut the roughgrade ahead of their Commander III towithin one inch (25 mm).

Highways built in days of old wereoften only 20 to 22 feet (6.1 to 6.7 m) inwidth. Most of the highways built todayare at least 24 feet (7.3 m) wide. Toimprove the safety of these olderhighways, many of them are widened.This is done by excavating along the sideand widening the base slab. The entire

roadway is then overlaid, resulting in anew, wider road. The excavation along theside is normally accomplished through theuse of an excavator of some type. Thegrade accuracy is less than desirable,causing the waste of paving material.GOMACO manufactures a specialtrimming attachment for the front of the9000 or the 9500 that allows trimming to aspecified width and an exact grade. Thenormal trimmerhead is removed and thespecial “shoulder trimmer” is installed.This trimmerhead is side-mounted,therefore keeping both tracks of themachine on the existing slab. Elevationand steering are normally taken off theexisting slab, providing for an accuratematch. The excess material that is trimmedcan be windrowed to the side for back fill,or it can be loaded into haul units to betransported off the job site.

Another contractor added a slurryspray bar to the front of his trimmerhead.He sprayed lime-stabilizing material onthe grade as he was trimming and mixedthe material into the base material. Thematerial was conveyed to the rear of themachine where it was then spread andcompacted.

So as you can see, with a littleingenuity, the GOMACO 9000 or 9500 canbe used for more than just trimming.

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Sidemounted trimmerhead widens roadways.

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Placing rock over a barrier wall for subgrade.

Placing concrete west of Fargo, North Dakota. Spraying lime-stabilizing material on the grade. Picking up windrowed asphalt off the grade.

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GRADE TRIMMERS ANDMOTOR GRADERS

a discussion with Kendall J. Kelly, GOMACO’s Southwest District Representative with over 30 years experience in the concrete construction industry

Bridges, buildings, and roadwayshave one thing in common, for anacceptable final product there must bean excellent foundation. In a roadway,the foundation is the subgrade orsubbase. Depending on thegeographical area, this may beanything from natural soils withvarious types of clays or sands, sometype of rock or a combination of these.

VARIATIONS INTHICKNESS AND DENSITY

Engineers usually design thesubgrade, or the material directlybeneath the concrete or asphalt paving,to perform at an optimum to allow forthe longest life of the concrete orasphalt paving. No matter what thecomposition of the subgrade, it shouldbe of a consistent density and cut to anelevation that is absolutely parallel tothe final surface placed on top.

This is important for severalreasons. With either concrete orasphalt, it is somewhat commonknowledge that equal thickness of

placed material while in the pavingmode will result in superior ridesmoothness. Since concrete must bevibrated for consolidation and asphaltis normally compressed with a roller,variation in thickness makes forvariation in density from top to bottomof the placed material. This is notacceptable for good, long-term results.

Cost is always an over-ridingfactor. When the concrete materialbeing placed is bid by the square yard,based on a specified thickness ratherthan by volume, it is essential that thesubgrade be accurate in relation to thetop of paving.

Concrete is almost always bid bythe square yard so accuracy of thesubgrade is always paramount.Asphalt in years past has normallybeen bid by the total weight in tons ofasphalt used. The more tons used, themore money in the contract. Not manyasphalt contractors were concernedabout overall thickness untilsmoothness specifications started toappear.

MOTOR GRADER ORTRIMMER?

Subgrade preparation is about tobegin. Do we use a motor grader or atrimmer? Both have their place on thejob site.

For many years motor graderswere used for final subgradepreparation because most roadbuilding contractors owned a motorgrader. They would normally beoperated by an individual who hadexpertise in cutting “fine grade.”

This was normally accomplishedby a surveyor setting what wereknown as “blue tops.” These weresimply square, wooden stakes driveninto the ground until the top of thestake, which was painted blue, wouldbe at the correct subgrade elevation.Depending on the profile of theroadway, there was usually a stakedriven every 25 or 50 feet (7.6 or 15.2 m) apart on each side of theroadway and also down the centerline.The motor grader operator wouldmake multiple passes on the roadway

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cutting the grade until he could see the“blue top,” and consequently, the finalsubgrade elevation was achieved.

Because of blue tops being cut outby the moldboard, this sometimesrequired multiple settings of the bluetops by the surveyors. This added timeand cost to the project.

Just as a side note... today, after theblue top is set to elevation, a “chaser”is nailed to the top of the blue top toaid the motor grader operator inknowing how close the blue top is tohis moldboard. The chaser is madefrom polyurethane strands that, afterbeing attached to the top of the blue top, stick up vertically about three orfour inches (76 to 102 mm).

The most common problem wasthat the area between the blue topsmay not be exactly the same elevationas over the blue tops because theoperators would push the moldboardof the motor grader down as theyapproached the blue top. Anotherproblem that the motor graderoperator would encounter would besubgrade density that would varybecause of different base materials andthe moldboard would not maintain thesame elevation as the operator desired.In other words, the moldboard may“ride up” or float over more densematerial and cut in deeper in lessdense material.

That is what separated the normalmotor grader operator from a good“blade man.” This situation is

compounded by the fact manyengineers specify either lime orcement-stabilized natural soils or selectmaterials. The mixing of thesematerials creates a very dense and,after some time, extremely hardmaterial that is almost impervious to ablade. The trimmer will in most casesbe able to cut this material accurately.

THE ADVENT OFSLIPFORM PAVING

Once preset stringline came intouse, with the advent of slipformpaving, many contractors used acombination of stringline and blue topsto attain their desired subgradeelevation. Also at this time, the gradetrimmer came onto the scene becausethis machine would follow the samestringline that the paver would follow.

This eliminated the necessity forthe surveyor to set blue tops, butsometimes they are still written in the

specifications for an additionalelevation check. The premise of thetrimmer is that with a rotating mandrelor trimmer wheel that has teeth evenlyspaced across the width of the wheel,the teeth are cutting the subgrade. Themoldboard that follows directly behindthe wheel is simply containing andscraping the excess loose material to beloaded on the loading belts.

This effectively eliminates theproblem of a motor grader with ablade or moldboard that may float overthe high-density material and cut intothe lower-density material. Thecomposition of the subgrade makes anenormous amount of difference in theway trimmers and motor graders reactto that material. One example wouldbe a subgrade that has a lot of claywhich, when compacted to density, isvery hard. The trimmer, because of itscutting action, “chips” away at thematerial and is able to maintain anaccurate grade, usually in onetrimming pass if the machine isoperated correctly.

The motor grader on the otherhand, with this same material, willhave a tendency to float over this hardmaterial. It may take several passes tocut it down to final elevation. Thisprocess occurs whether the machine isoperated manually or if it has sometype of sensor system to follow thestringline or is GPS/Laser databasecontrolled.

Another example would be asubgrade material consisting of mainlyaggregates and sand with not muchclay or “binder” present. This type ofmaterial shears very easily and even ifcompacted to high density will beeasily cut by a motor grader following

A 9500 trimmer makes a cut through frozen ground on a project in Grand Rapids,Michigan, in the middle of January.

Sensoring off dual stringlines averages theerrors in the stringline from each side,trimming the grade exactly the way thepaver will see the stringline.

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a stringline or GPS/Laser databasecontrol. The trimmer will also cut thismaterial with ease.

OTHER ADVANTAGESOF A TRIMMER

When trimming what is known asselect material, such as previouslyplaced aggregate base, lime or cement-treated base or even lime orcement-stabilized natural soils, theexcess materials that come from thetrimming operation can be loaded on atruck while trimming and hauled toanother area on the job site where alow-grade condition exists.

This keeps the contractor fromwasting the high-cost select material.Even if select material is not used andlocal soils are being trimmed, theexcess material can be moved to theback side of the stringline where it canbe used for backfill to the edge of slab.This saves the contractor time andmoney. He can accomplish a task whiletrimming that would either requiretearing down stringline or several extrapieces of equipment to move thematerial. If the local material is neededelsewhere, it can be loaded on a truckwhile trimming, again savingadditional equipment and expense.

STRINGLINE CANAFFECT THE FINISHED

PAVING THICKNESSBoth trimmer and motor grader

slope controls are very accurate. Inmany cases the slope controls are soaccurate they point out irregularities inthe setting of the stringline.

This is usually seen when the slopecontrol is used to transfer the stringlinegrade on a given slope to the centerline of the roadway. When making thereturn pass on the opposite side, withthe same amount of slope in theopposite direction, if the subgradeelevations do not match in thecenterline there is obviously a problem!

Normally this comes from smallerrors that occur when setting thestakes for the stringline and then othersmall errors when setting the stringlineitself. If these errors are all negative orpositive, the amount of error can beenough to cause concern about finishedpaving thickness.

One way the trimmer helpseliminate this is by using the extendedsensor booms to sense both stringssimultaneously while trimming. Thiseffectively averages the errors in thestringline from side to side, thereby

trimming the grade exactly as thepaver will see the stringline, which isboth sides at the same time. This keepsyield loss to a minimum.

Since the trimmer is not onlyfollowing the stringline for grade butalso alignment, it makes the processvery easy. On the other hand, themotor grader is usually drivenmanually and doesn’t normally have away to sense elevations of twostringlines that may be as much as 40 feet (12.2 m) apart. Threedimensional laser/database controlsystems, properly operated, eliminatethis situation.

– KEY POINTS –•Accurate grade control regardless of

trimmed material density•Less reliance on highly experienced

motor grader operators•Single pass operation saving time•Ability to place material while

trimming behind stringline, savingtime and extra equipment

•Ability to place material whiletrimming into trucks for removal,saving time and extra equipment

•Ability to sense two widely spacedstringlines simultaneously

GOMACO trimmers can either discharge into haul units for easy removal or over the stringline for backfill material.

A 9000 trimmer is controlled by the Laser Alignment stringlessguidance system as it trims grade on a project near Panora, Iowa.

Photo by Tom Grell 22-99-4-A

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Astaldi uses their GT-6300 with high-drive track toslipform a 15.7 foot (4.8 m) pass for a new roadwaynear Santa Ana, El Salvador.

Hydropower Engineer Bureau #13 use their GP-2600 to pave anew 30 feet (9.2 m) wide, nine inch (23 mm) thick roadwayconnecting China to Pakistan. They are currently paving nearKashi City, in the Xinjiang province of China.

Lambert & Grenier slipform ribbon curb intight-clearance conditions on a project inDrummondville, Quebec, Canada.

AMEC slipforms a slab 25.6 inches (650 mm) thick as part of atest pour at the Heathrow Airport in London, England.

A new generation Commander III with a rear-mounted auger finishes a test pour in Toulnoustouc,Quebec, Canada. Aecon will be slipforming invertedstairway to form the sides of a dam.

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Meltreach Proprietary Ltd. is the slipform contractor on thefirst ever slipformed barrier in the Philippines. They are usingtheir GT-6300 to slipform wall as tall as 6.1 feet (1.85 m).Meltreach has approximately 12.4 miles (20 km) of the Texas-type barrier to slipform on the North Luzon Tollway nearManila for the project’s main contractor, Leighton Asia.

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Giant Construction Guamslipforms four inch (102 mm)thick, 7.5 feet (2.3 m) widesidewalk on a project in front ofthe Micronesia Mall in Guam.

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GOMACO will be the first paver manufacturer torepresent true slipform paving on a civil aviationairport in Japan. Chubu, the new international airportnear Nagoya, Japan, will be built by three consortiums,each made up of three Japanese contractors. Two of thethree consortiums will be using GOMACO equipmenton the project and Taisei-Rotec, a Japanese contractor inone of the consortiums, will be supplying theirGOMACO PS-60 placer/spreader and GHP-2800 paver.

The project will be paved in passes 24.6 feet (7.5 m)wide and 18 inches (460 mm) thick. Edge slumpconcerns are a major consideration on this project andsince it’s the first slipforming on an airport in Japan,everyone wants to see it succeed.

“Taisei purchased the GHP-2800 specifically for thisjob,” Tim Nash, GOMACO International Regional

Manager - Asia Pacific, said. “They decided topurchase a GOMACO because they had seriousconcerns about meeting the criteria on this extremelyimportant ‘first ever ’ slipform construction on a civilaviation airport.”

Over 50 visitors were on site from 17 differentcompanies, including the Japan Slipform Associationand the Central Japan International Airport Company,to watch the initial paving test.

“All present were in agreement that the tests wereextremely successful and ‘true’ slipforming with theGOMACO GHP-2800 gets the green light for Japan’sChubu Airport,” Nash said.

Watch for a future story on the Chubu Airport in afuture edition of GOMACO World magazine.

The GHP-2800 impressed Japanese officials and had no problems with edgeslump on a test project for the new international Chubu airport nearNagoya, Japan. Each paving pass is 24.6 feet (7.5 m) wide and 18 inches(460 mm) thick.

GHP-2800 Chosen for Japanese Airport