Technical Quarterly, vol. 4, no. 3
Contents
1. by Steve Golding P E and Kathleen Jones Division 10 Research Section District 11 Lufkin is enthusias tic about a new method for con structing guard fences During the 1988 construction season the Dis trict contracted to have 18 946 feet of guard rail on SH 147 removed and replaced The contract was let with an estimate of the percentage of reusable rail but stipulated the use of new nuts bolts and posts Marcus Construction Corporation an out of state firm with a regional office in Cedar Hill Texas under INSIDE Pile Driving Hazards ustralian Electronic Tags 3 Geotextiles Reduce Bridge Maintenance Vol 4 Issue 3 AN EXCHANGE OF IDEAS Editor October 1988 Kathleen M Jones bid all the conventional method operators with a highly efficient innovative construction method With a crew of four to five and a truck mounted drilling and pile driving rig this contractor was able to remove and replace 1000 feet of rail per day The average conventional method crew of five might be able to remove and re place around 500 feet per day Reusable rail in the 18 946 feet Published by the Texas State Department of Highways and Public Transportation Transportation Planning Division Research and Development Section Technology Transfer Subsection P O Box 5051 Austin TX 78763 5051 Y Se 2 A T EA 3 FIG 1 Truck mounted drilling and pile driving rig INNOVATIVE GUARD RA2. They act by dispersing individual cement particles throughout the paste suspension Analysis of har dened concrete made with super plasticizer often shows finer particles and denser structure within the cement paste If properly proportioned and placed concrete made with a HRWR is of good durability and low permeability However there are problems associated with the use of HRWR careful consider ation of the intended application and job site must be made and like any admixture HRWR must not be used in place of good con creting practice The problems of either segregation and bleeding or sticky difficult finishing can be overcome by carefully adjusting the HRWR dosage and by care fully proportioning the mix par ticularly selecting an optimum fines content Other problems can be dealt with by following guide lines and by developing a practical work plan The approved work plan like a plan note should su persede SDHPT highway specifica tions Suggested guidelines and ideas for developing such a work plan have been outlined in this article For more information contact Mr Gerald Lankes D 9 TEX AN 241 7331 512 465 7331 or Mr Berry English D 5 TEX AN 245 5093 512 371 5093 REFERENCES i Eckert William C and Carrasquillo Ramon L Preliminary Draft Re search Report 1117 2 Austin Univer sity of Texas CTR June 1988 2 Lankes Gerald D Admixtures for Concrete Paper presented
3. Division D 9 recommends a mix Hypothetical Slump Loss Versus Time Curve concrete temp 95 F measurements taken every 15 minutes from initial addition of HRWR Initial Dose of HRWR at Job Site Time Elapsed mins FIGURE 3 60 90 Maximum Time Allowed By Specification For this mix at 95 F with only one redose allowed the placement time limit would be 80 minutes 10 I General Data er also capable of operating at an agitating speed A 3 Batch design and equip B ment A copy of the batch design should be included Construction C Structural Element s D E Project No Control No amp County Structure Name s form 309 may be used to show all the pertinent information Pro posed procedure suggests that the contractor supplier prepare and Contractor Concrete Supplier 7 F Cement Type and Brand test at least one full sized batch using the equipment and batch de G Course Agg Source and Grade sign to be used on the job To H Fine Agg Source ensure adequate mixing recom mend the batch should be no more than 75 percent of the mixer Admixtures Brand Name amp Recommended Dosage Range capacity SDHPT personnel should Air witness all tests preferably with Retarder the project inspection team 4 Batching sequence Any Water Reducer admixtures to be added at the _ High Range WR plant and their dosages and Narrative on recommended c
4. Texas 78701 2483 512 465 8353 or TEX AN 258 8353 1 16 REFERENCES Chang E C C J Messer and B G Marsden Analysis of Reduced delay Optimization and Other Enhancements to PASSER 11 80 PASS ER Final Report FHWA TX 84 50 375 IF Col lege Station Texas Transporta tion Instititute April 1984 ADDENDUM PASSER version 3 0 Microcomputer Environment System User Instructions Austin Texas State Department of Highways and Public Transportation September 1986 Chang E C J C Lei and C J Messer Arterial Signal Timing Optimization Using PASSER II 87 Micro computer User s Guide FHWA TX 88 467 1 College Station Texas Transportation Instititute July 1988 T STAFF Director Cindy King 512 465 7682 Ass t Director Debbie Hall 512 465 7684 Editor Tech Writer Kathleen Jones 512 465 7947 Information Specialist Jim Manning 512 465 7644 Librarian Liz Humphrey 512 465 3082 Our TEX AN exchange is 241 SECOND NOTICE A r The State Appropriations Act requires all state newsletters and other periodicals to present a notice in three consecutive issues indicating That anyone desiring to continue to receive the publication must so indicate in writing The agency shall furnish future publications only to those persons requesting This does not apply to department employees who receive their issues through departmental distribution
5. give a brief account of some typi cal HRWR applications and will outline information and provide guidelines for developing a suit able work plan for its use APPLICATIONS Some main applications of HRWR are I Adjusting strength 1 Increasing the strength of a 4 to 6 sack concrete mix with out increasing cement content The water reducing capacity of superplasticizers is used to pro duce a high strength concrete of normal workability from standard good quality materials Fig 1 2 Producing workable high strength concrete greater than 6000 psi with very low wa ter cement ratio with an increased cement content a 7 to 9 sack mix and with no exotic materials such as silica fume Water content can be reduced by up to 30 percent In fact concretes with water cement ratios as low as 0 28 have been designed and placed successfully 3 p235 Precasting of prestressed ele ments is an area where special high strength requirements often occur Fig 2 High strength mixes achieve release strength ear lier allowing earlier form removal resulting in increased production and reduced fuel costs associated with steam curing H Adjusting slump without increasing water content 1 Producing high slump normal strength concrete The ce ment particle dispersing properties of superplasticizers enable the mix to be made more workable with out changing the water cement ra tio 2 Producing high slump high str
6. individual cement particles through the paste Because they increase workability superplasticizers are capable of reducing the water con tent of a concrete mix by 15 to 30 percent without reducing slump or of producing a high slump in con crete without changing the wa ter cement ratio HRWRs differ chemically from regular water re ducers The three primary materi als from which HRWRs are made are 1 sulfonated naphthalene formaldehyde condensates 2 sulfonated melamine form aldehyde condensates and 3 modified lignosulfonates All superplasticizers must meet ASTM C 494 Type F or Type G standards By definition admix 7 tures of these types reduce the quantity of mixing water required to produce concrete of a given consistency by 12 percent or great er Type F does not retard the set Type G does retard the set 2 At the moment only Type F has been tested and approved by Ma terials and Tests Division D 9 Although relatively expensive the total cost of a superplasticizer may be as high as 4 00 per yard of concrete in a typical sack mix superplasticizers can yield economic benefits in certain types of applications 1 HRWR con cretes in general offer higher strengths and lower permeabilities than can be had with conventional concretes Also they are often more abrasion resistant 1 HRWR admixtures should never be used as a substitute for good concreting practice however Good concreting
7. small amounts to act properly as a dispersant Add any hold water specified by design before the ad dition of the HRWR After the addition of hold water the con crete should be mixed a specified minimum number of revolutions 1 Introducing HRWR after all the mix water has been added in sures that the correct amount of admixture will be left in solution to cause dispersion and raise initial slump to the desired slump 1 3 p219 2 Be aware that naphtha lene based superplasticizer can sig nificantly reduce the effectiveness of nevtralized vinsol resin and oth er specifically developed air en training agents In high slump concrete it is often more difficult to retain entrained air If air loss is a problem it may be necessary to reproportion the mix to achieve the desired results 1 e Maintaining Quality Control l 1 Use approved D 9 sources to assure that cement ag gregates and admixtures have consistent physical and chemical properties 2 Inspect all mixing trucks prior to use Trucks with worn blades build up on mixing blades or other deficiencies that will reduce mixing efficiency should not be used to mix HRWR con crete 8 3 Disperse HRWR onto the bulk of the mix rather than the blades of the mixer by using a rigid extension attached to the dis pensing hose 1 2 4 Conduct intermittent slump and air content tests moni toring fresh concrete temperature and casting cylinders and or
8. 45 min Time to Set Air Content 30 min F G H 1 J K ky M FIGURE 5 Mix design using HRWR continued il that the concrete used to develop these curves be batched under the most critical temperature condi tions anticipated Fig 3 In order to have a meaningful curve the stump and temperature should be taken every 15 minutes The slump loss versus time curve will be used to establish placement time limits for the anticipated maximum concrete temperature Establishing placement time limits for a mix at a given temperature helps to eliminate any placement consolidation and finishing prob lems which may arise from the use of HRWR Data provided on the curve will indicate the range of temperatures the maximum tem perature down to 60 and maxi mum placement time that the specific concrete can be handled adequately in the field 6 Temperature control The maximum acceptable concrete temperature must be given in the work plan It must be based on standard specifications or slump loss versus time at the maximum anticipated temperature curve whichever is lower In trial batches if one batch exceeds the anticipated maximum temperature run a time versus temperature curve for that temperature and document the concrete s behavior If the concrete does not show un usually rapid slump loss or finish ing difficulties it may be possible to use the newly established curve as the maximum t
9. as a finishing aid Trying to achieve an adequate appearing surface in this way will only harm the durability of the critical top quarter inch Try to avoid rapid slump loss and other problems by following these guidelines Avoiding Rapid Slump Loss 1 Estimate a reasonable Y wing segmental bridge in San Antonio Most precast transit time from the location of the ready mix plant to the job site Use this estimate to establish a time for the initial dose of superplasticizer to be added to the fresh concrete The HRWR is to be added to the concrete at the job site within a certain time as specified by the work plan to aid in controlling rapid slump loss 1 2 Add retarding admixture at the plant if the reasonable time for addition of HRWR is estimat ed at more than 30 minutes 3 Evaluate the trial batch slump test results plotting a slump loss versus time and a tem perature versus time curve Limit ready mix truck loads to a volume that may be placed and consoli dated within the time frame for continuing acceptable workability as determined by the slump loss versus time and the temperature versus time curves To ensure adequate mixing it is recommend ed that the ready mix trucks will need to be limited to 75 percent of their rated capacity 7 4 Loss of workability is lessened at lower temperatures 3 During hot weather retarding ad mixtures should be used with superplasticizers Retarders help of
10. begins with a good plastic mix design Avoid harsh rocky mixes Rocky mixes don t superplasticize well and will be prone to segregation bleeding and honeycombing Optimum coarse and fine aggregate factors need to be selected and tested in trial batches using representative job materials Another major problem which may be encoun tered using superplasticizers is un usually rapid slump loss which really means a sudden loss of workability within what should be acceptable placing time The rapid slump loss appears to be an inher ent difficulty with ASTM Type F admixtures It can be controlled but not eliminated by some prac tical steps explained later in the Guidelines section To encourage good concreting practice the Department has in cluded the following data note on the special provision sheet to Item 437 High range water reducers will be used only to meet special requirements and will require the written approval of the Engineer on each specific project A sat isfactory work plan for control shall be submitted by the Contrac tor for approval and evaluation of the concrete containing the admix ture will be performed by the En gineer Certain guidelines must be followed and a work plan must be developed for each job to cov er natural variations in chemistry of different mix materials and dif fering job conditions to avoid ma jor problems associated with the use of HRWR This article will
11. sticky and difficult to finish a slight decrease in sand to total ag gregate ratio may eliminate the problem 4 p33 Failure to achieve an optimum fines content may result in segregation and ob vious bleeding 3 p230 2 Use the minimum amount of HRWR needed to achieve the specified w c ratio and slump The dosage to attain a giv en slump will depend in part on the initial slump Mixes with low intial slumps of 1 to 2 inch will require higher dosages of HRWR 9 than will mixes with greater initial slumps In general the slump gain _ increases as the amount of HRWR increases up to a maximum effec tive dose Past this dose increases in superplasticizer do not yield more benefit 3 p228 Excessive amounts of HRWR in addition to being uneconomical may result in segregation bleeding and loss of entrained air 8 Excess super plasticizer bleeding to the surface will leave an oily residue that will not allow another layer of con crete to bond properly The sur face of an over superplasticized mix may also show unusual crust ing 3 Keep in mind that HRWR high slump concrete re sponds very quickly to vibration Vibration should be kept to the minimum necessary for adequate consolidation or overvibration may result 8 e Avoiding Undesirable Chemical Admixture Interactions 1 Concrete must be thor oughly mixed before adding HRWR or the HRWR will be ab sorbed irreversibly leaving only
12. with a bolt hole in the rail A hole slightly smaller than the post is drilled The post placer picks up a post and sticks a metal rod through the hole in the post He then positions the post onto the posthole The operator uses the pile driver on the rig to drive the post The post placer stops him when the metal rod in the post comes to the correct eleva tion The post placer removes the metal dummy and pushes the ac tual bolt through the post and rail He hand tightens the nut at the back A third crew member fol lows with a power torque wrench tightening the bolts on the posts and lap slices A fourth crew member checks the soil at the base of the posts tamping it with a shovel when necessary The procedure is very precise with no time wasted trying to bolt a rail to a post that is too far away It takes about one minute to drill the posthole drive the post and then bolt the post to the rail District 11 videotaped seg ments of the construction method Watching the videotape through many consecutive post settings it is obvious that this procedure worked very well Every post was placed quickly and accurately without a single post having to be pulled up For more information contact Mr Walter Hearnsberger San Augustine Resident Engineer District 11 409 275 2541 A copy of the unedited un narrated video footage is available on loan from the D 10R Technology Transfer Library TEX AN 24
13. work to avoid working under pile driving rigs where the risk of injury is great It is recommended that penetration readings be taken with the aid of a transit or level set up a safe distance from the rig Various methods have been used to accomplish this such as taking readings from a gauge attached to the pile or hammer or by marking the pile with increments to be used for taking penetration readings Sometimes it might be necessary to work within a cofferdam If so try to perform the necessary work or measurements from the area farthest away from the rig to avoid falling objects but if at all possible try to perform all inspections from outside the cofferdam when driving opera tions are in progress Ear plugs should be used when working within a cofferdam to prevent injury to the ears by the loud noises caused by driving Stay alert and look for signs of failure or other hazards which may cause injury if any are noticed alert workers and any other persons of the danger stop the driving opera tions if necessary until the hazard is removed Play it safe From SDHPT Bridge Tips No 13 DECEMBER 1985 published by the Bridge Division D 5 of the Texas State Department of Highways and Public Transportation w GEOTEXTILE WALLS REDUCE BRIDGE MAINTENANCE COSTS by John T Price P E Price and Company Inc Wyoming MI An innovative use of geotextiles by the Wyoming Highway Depart ment has significa
14. 1 7644 512 465 7644 Drawing from videotape ie a FIG 3A amp B Driving the post to correct elevation 3 ELECTRONIC TAG IS MADE IN AUSTRALIA The electronic license tag af fixed to cars in the Hong Kong congestion pricing experiment AITO 4 86 was made in the U K A competing version seeking world wide applications has now been developed in South Austra lia a part of the world noted for its public transport innovations The proprietary TransiTag elec tronic vehicle identification sys tem consists of a fixed onboard transponder device which can be interrogated from remote locations to provide a unique vehicle iden tity code and operational data such as the current mileage read ing It is also possible to obtain variable data such as the load content weight destination and driver identification to build the essential components of a comput erized fleet management system The electronic license plate makes possible the automation of fuel dispensing weigh bridges parking garage access and timekeeping In the case of public transport and emergency services the developers of the TransiTag system note that it can be interlocked with traffic light controllers to provide inter section priority for buses ambu lances and police cars As in the Hong Kong demonstration the TransiTag transmits its code and data as it passes over a detector loop A roadside interrogator unit decodes the messa
15. ART SUMY optimal signal timing plans for each intersection INT SUMY a series of level of service evalua tions for each phase BEST SOLN total arterial sys tem performance ART MOB signal controller phase interval set ting report PIN SET and the optimal time space diagram TS DIAGM if requested The implementation of the optimal timing plans can be greatly facili tated through the use of phase in terval tables with respect to the system master intersection for the microprocessor based traffic actu ated signal equipment Fig 2 3 PROGRAM IMPLEMENTATION The program permits the engi neers to interact with the overall analysis process while relieving them from the tedious and repet itive manual calculations Several program runs and some engineer ing judgment in the selection of proper input parameters may be needed before the final signal tim ing solutions can be produced In response to the user desire to modify the embedded input data used in analysis new features have also been added to let users adjust PASSER II 87 OFFSET REFERENCE OTHER INTERSECTING ARTERIAL MASTER INTERSECTION REFERENCE INTERSECTION CURRENT ARTERIAL UNDER ANALYSIS REFERENCED MOVEMENT lt Ss MOVEMENT 6 MOVEMENT 2 gt REFERENCED PERIOD BEGIN END FIGURE 2 PASSER II 87 offset reference w PASSER 0 87 EMBEDDED DATA INPUT SCREEN Pretimed or Actuated P or A P Ideal Saturati
16. IL PLACEMENT was estimated at 80 percent Mar cus bid was 50 cents a lineal foot to remove old rail and 9 00 a lineal foot to place new Currently many contractors drill or excavate holes much larger than the diameter of the posts align the rail on jigs hangers then attach the posts to the rail and backfill the postholes Often with this method the posts are difficult to keep in alignment as hl i Drawing from videotape they are being backfilled this sometimes results in poor align ment of the rail Another problem with this method is that the posts settle unevenly over a period of a few months pulling the rail out of alignment The new method over comes both of these problems by aligning the rail first on hangers pile driving the posts into holes near to or slightly smaller than post diameter and then attaching the rail to the posts Little or no backfilling is necessary After each 25 foot section of rail is placed on a pair of jigs hangers in proper horizontal and vertical alignment a truck with a trailer load of posts follows A crew unloads four posts per sec tion to the back of the rail Next in the sequence is the truck mounted drilling and pile driving rig The operator drives the rig along the guard rail until the per son on the ground who places the posts signals to the operator to stop The post placer helps the operator position the auger so it aligns
17. actors inexperienced in this application An update from the Wyoming State Highway Department s Chief Engineering Geologist W F Sher man P E We utilize the fabric reinforced design in areas where settlement is anticipated within the fill We do not utilize the reinforcement where the settlement is in the foundation below the fill or where the fill material is not susceptible to settlement At the present time the Uni versity of Wyoming has instrumented an installation west of Cheyenne for the Department This project was completed last fall 1987 and we have received no definitive information at this time Dr Tom Edgar of the Univer sity of Wyoming is the research contact for this project The D 10R Technology Transfer Li brary has been placed on a list to receive data on the project as it becomes available REFERENCES 1 Steward John E Williamson R and Mohney John Guide lines for Use of Fabrics in Construction and Maintenance of Low Volume Roads United States Department of Agricul ture Forest Service Portland Oregon June 1977 2 Guido V A Chang D K and Sweeney M A Bearing Capacity of Shallow Founda tions Reinforced With Geogrids and Geotextiles Preprint Volume Second Canadian Symposium on Geotextiles and Geomem branes Edmonton Alberta September 1985 pp 71 78 3 Bell J R Barrett R K and Ruckman A C Geotextile Earth Reinforced Retaining Wall Test
18. alysis period number of left turn sneakers in dividual phase lost time combined left turn phase reference delay level of service evaluation total delay adjustment factor basic HCM delay criteria permitted left turn models and the recommend ed left turn model coefficients Another new feature in PASSER II 87 is the addition of the data input ASSISTANT function for assisting users to input the traffic movement related information graphically such as the turning traffic movement volume VOL UME saturation flow rate SAT FLO and the minimum phase time MIN PHS The program s ASSISTANT allows users to analyze the movement based infor mation freely following the analy sis procedures similiar to the 1985 Highway Capacity Manual HCM Fig 4 LEFT TURN SIGNAL TREATMENTS Due to the need for assisting users in analyzing different left turn signal treatments under co ordinated progression analysis PASSER II 87 has been signifi cantly enhanced These improve ments include the data input procedure input data structure green split calculations progres sion calculations and program output evaluations PASSER II 87 left turn input uses the minimum amount of input information to generate the possible left turn treatments as well as the allowable signal phase sequences The input data was designed to simplify the user s input for analyzing the var ious possible left turn signal treat me
19. at the 32d Annual District Laboratory and Engi neering Personnel Meeting Abilene Texas March 23 24 1988 3 Ramachandran V S and Malhotra V M Chapter 4 Superplasticizers Concrete Admixtures Handbook Park Ridge New Jersey Noyes Publica tions 1984 4 Schutz Raymond J Proportioning Concrete for High Range Water Re ducers Paper presented at National Readymix Association Concrete Troubleshooting Conference Milwau kee Wisconsin May 17 20 1987 5 Texas State Department of Highways and Public Transportation TSDHPT Bridge Division Concrete Construction Manual Construction Bulletin C I Austin TSDHPT 1982 6 TSDHPT Construction Division Con struction Manual rev ed Austin SDHPT 1986 7 TSDHPT Item 360 1 Water Cement Ratio Item 420 Concrete Struc tures and Item 437 Concrete Ad mixtures 1982 Standard Specifications for Construction of Highways Streets and Bridges Austin SDHPT 1982 8 Whiting D and Schmitt J Durability of In Place Concrete Containing High Range Water Reducing Admixtures NCHRP Program Report 296 Wash ington D C Transportation Research Board 1987 Good Advice Before Doing Anything 5 THINK y y 12 PASSER I 87 MICROCOMPUTER PROGRAM SYSTEM by Edmond C P Chang Ph D P E Texas Transportation Institute A amp M University System INTRODUCTION PASSER Il 87 is the acronym for Progression Analys
20. channels other than the U S mail To remain on the mailing list for Technical Quarterly all others must respond by returning the notice properly signed and dated to Signature Address Technical Quarterly Kathleen M Jones P O Box 5051 Austin TX 78763 5051 Date y
21. dorsement or advertisement of a particular product by the Texas State Department of Highways and Public Transportation Continued on page 16 The information contained herein is experimental in nature and is published for the development of new ideas and technology only Any discrepancies with official views or policies of the TSDHPT should be discussed with the appropriate Austin Division prior to implementation of the procedures j em qwe cam eee ee ee a Ce Ce Ce Technology Transfer Technical Quarterly Texas State Department of Highways and Public Transportation D 10 Research P O Box 5051 Austin Texas 78763 5051 PASSER I1 87 Con t from page 15 proved user specified controller Phase Interval Setting PIN SET report and an enhanced optimal Time Space diagram TSDIAGM A Microcomputer User s Guide has been written to be dis tributed with the program pack age It was developed for those users who are already familiar with the PASSER II program and desire to use the PASSER II 87 microcomputer program to analyze arterial signal system design prob lems 3 Any questions concern ing how the PASSER II program Operates or what type of data in put it needs will be best answered in the PASSER II User s Man ual Please address all written correspondence or requests to the State Department of Highways and Public Transportation File D 18STO PASSER Il 87 11th and Brazos Streets Austin
22. emperature 7 Concrete strength Com pressive or flexural strength de pending on job requirements should be performed on the con crete being used to develop the slump loss versus time and tem perature versus time curves 8 Mixing time The mixing time mixing revolutions prior to and after the addition of HRWR must be specified 9 Redose Any conditions that may require a redose of HRWR if allowed should be in dicated Also include the redose dosage permissible slump range and the mixing time after redose 10 Air content Air content if required should be taken be fore and after the addition of HRWR If redoses are allowed it should also be checked after the redoses 11 Contractor s precon Struction responsibilities Specify that the contractor is to plan hold and document a special preconstruction and training con ference to discuss the results of testing the proposed mix design the anticipated site conditions and potential problems SDHPT pro ject personnel responsible for ma terial control are to participate SUMMARY High range water reducers HRWR also known as super plasticizers are chemical admix tures that can reduce water content in concrete mixes by up to 30 percent They are used in the production of high strength great er than 6000 psi concrete of nor mal workability high slump concrete of normal strength and high workability and high strength high slump concrete
23. ength concrete Super plasticizers can be used with high strength mix designs to increase the workability from stiff through normal to extremely plastic Fresh high slump HRWR con crete is cohesive and can be con solidated with limited vibration two useful properties in a prestressed casting operation High slump high strength con _ _ i FIGURE 1 A possible application for stronger than average concrete Bridge rails to contain and redirect 80 000 lbs trucks FIGURE 2 prestressed elements were cast using HRWR high strength concrete crete is especially useful in bridge structures which have heavily con gested steel reinforcement Re search shows that the addition of a superplasticizer can raise the steel concrete bond strength in both normal and lightweight concrete 3 p250 Fine dispersion of ce ment particles makes the increase in bond strength possible HRWR can be used in many applications such as the production of lightweight concrete concrete containing fibers fly ash concrete pumpable concrete for underwater placement and blast furnace slag concrete however HRWR should be used only when necessary to meet a specific need TROUBLESHOOTING HRWR concretes are frequently more difficult to handle because they can suffer rapid loss of work ability Do not attempt to correct rapid slump loss by the addition of retempering water by over vigor ous finishing or by use of water
24. f expansion joint failure DESIGN TECHNIQUES AND CONSIDERATIONS Using the guidelines presented by Steward et al 1 the WHD analyzed walls having configura tions similar to those shown in Figure 1 reprinted from working drawings Steward s approach uses conventional geotechnical design assumptions and is suitable to design structures both with and without wing walls Figure 2 pro vides a three dimensional schemat ic of a geotextile configuration for wing wall type structures The WHD designed each GRS wall to account for local geometry fit height foundation soil rock slope surface contours etc soil con ditions and live loads Because this analytical method does not ac count for the composite effect of multiple reinforcing layers conser vatism inherently results Full scale 97 Corbel Normol to Atui Slope to Motch g Grade Slope IX M 732 2 64 ot RF Abur Compocted bockfitt t f peewee Moteriol Typ Excavotion ond backtilt FIGURE 1 Bot tom of Abutment Footing Place Parforoted Plastic Pipe adjecent to footing Representative wall configuration 5 FIGURE 2 Typical Layer of Fabric Near side wingwall not shown for clarity field research 2 verifies this con servatism In essence the analysis provides direction to the following unknowns 1 number of rein forcing layers required 2 tensile stren
25. flexural strength beams These tests will detect a temperature rise in the concrete and will ensure that minimum strength specifica tions are met 1 5 Mix the concrete thor oughly for the amount of time specified by the work plan after the addition of superplasticizer Placement should begin immedi ately 6 Use standard good con creting practice throughout WORK PLAN DEVELOPMENT The main objective in developing a detailed work plan is to establish a procedure and prac tice that will allow the consistent production of superplasticized con crete in agreement with the con crete specifications and specific conditions of the job including materials selection proportioning batching mixing and casting The developed work plan should include the following from reference 2 unless otherwise indicated 1 Purpose Reason for using a superplasticizer Here the con tractor will justify its use 2 Information relating to the materials and concrete mix de sign Proposed procedure recom mends that the contractor supplier should prepare and test small vol ume batches containing HRWR and record this information in a manner similar to Figures 4 and 5 specification slump range should be used It is desirable that a SDHPT representative witness these tests Note A small por table type mixer capable of mixing enough concrete to perform the tests outlined in Figures 4 and 5 should suffice Materials and Tests
26. fset rapid slump loss by slowing the initial set 1 Also if changing conditions threaten to raise the concrete temperature above the work plan s specified maximum hot weather concreting measures have to be taken to ensure that the concrete mix temperature re mains at or below the maximum 5 Redose the fresh con crete with HRWR if it does not reach design slump with the initial dose this does not apply to air entrained mixtures With the ex ception of air entrainment a second dose of superplasticizer will not harm concrete properties It may however extend the setting times noticeably This would not be a problem with formed fin ishes such as columns 1 The concept of a sequence of doses at specified intervals determined during trial batching is useful in avoiding rapid slump loss during hot weather HRWR concreting 3 p239 6 Plan placing and finishing operations for maximum efficiency Quick competent han dling avoids leaving concrete wait ing in the mixing trucks The less time that passes the less time the concrete has to stiffen Avoiding Segregation Bleeding and Finishing Difficulties 1 Design a mix that is ap propriately proportioned for the intended superplasticizer applica tion To prevent bleeding in lean to medium cement content mixes an increase in sand to total aggre gate is usually necessary In rich mixes the normal ratio is usually satisfactory buty if the trial batch is
27. ge and converts it into a computer readable format which can be sent over a phone or cable system to the fleet management mainframe From AASHTO International Transportation Observer Washing ton D C The American Associ ation of State Highway and Transportation Officials April 1987 Used by permission PILE DRIVING HAZARDS There are certain hazards associated with pile driving of which field personnel must be aware in order to avoid injury or more serious consequences The following safety precautions are taken from SDHPT Construction Bulletin C 8 Pile Driv ing Manual FIGURE 1 Are you at risk 1 Be certain that boiler and steam or air lines are in good operating condition and do not contin uously stand near them as they may fail causing serious injury 2 Stand clear of the driving rig while it is being moved or set up 3 Stand clear while piling are being hoisted into position for driving 4 Always wear safety helmets safety goggles and any other safety gear that will protect against injury while working under the rig during driving operations In addition to the above working under a rig should be avoided by inspection personnel if at all possi ble Pieces of concrete or steel have been known to spall from piling driving helmets hammers etc while piling are being driven Such falling pieces have been known to cause serious injury and even death Inspection personnel should arrange their
28. gth necessary for each rein forcement member 3 length of each reinforcement member and 4 distance between reinforce ment layers These four design elements are mutually depen dent altering one has an effect on the others Once the wall ele ments are determined the com posite structure of soil and reinforcement material is analyzed as a rigid body for resistance to rotational and sliding failures Finally a review of the foundation soil s bearing capability is made While the Steward approach provides details of wall component placement and structural require ments several incalculable benefits are derived from using GRS walls Specifically multiple reinforce ment layers significantly increase the overall fill stiffness 3 With greater stiffness better compaction is possible and less traffic induced settlements result The increased density also translates into greater shear strength for cohesionless soils Therefore loads are distrib uted more quickly and evenly reducing differential consolidation Geotextiles placed as shown in Figure 1 confine separate and fil ter the embankment s cohesionless soils Migration of particles into the subsurface drain systems or through joints in the structure is prevented Therefore GRS walls inherently prevent this contrib uting cause of soil support loss GRS walls are normally con structed without the presence of abutments or wing walls they have the capabil
29. harging sequence and mixing times at plant and job HRWR dosage rate and addition gt i i PUBS i TON p l 8 site maximum batch size dosage rates maximum and desired slump special method should be included in the procedures to control segregation work plan When recommending If pumping is proposed the slump before and after pumping and the air content the HRWR addition rate and before and after pumping should be considered and documented method the slump range in which If multiple dosing with HRWR is allowed at site this procedure should be modeled the admixture will be added must and tested on the full volume trial batch with appropriate air and slump testing also be identified including air and slump loss with time The re dose dosage rate must be specified i and included in the narrative 5 Slump loss versus time curve and temperature versus time Include a graph showing the slump loss vs time and concrete temperature curve Include in the work plan ll MIX DESIGN USING HRWR continued BASE MIX Course Aggregate Ibs Fine Aggregate Ibs Cement Ibs Water Admixtures 1 Air oz 2 Retarder oz 3 Water Reducer oz 4 High Range WR oz Cement Factor sacks yards Workability Factor Cement Water Ratio gal sack Slump initial in Air Content Concrete Temperature Air Temperature Strength 1 7Day Beam 2 28 Day Cylinder Slump Loss 1 Initial 15 min 2 Initial 30 min 3 Initial
30. is and Sig nal System Evaluation Routine PASSER II was originally devel oped by the Texas Transportation Institute TTI for the Dallas Cor ridor Project The Texas State Department of Highways and Pub lic Transportation SDHPT has sponsored the subsequent develop ment of PASSER II on both mainframe computers and micro computers 1 The theory model structure methodology and logic of PASSER II 87 have been eval uated and documented PASSER II has received widespread usage because of its ability to easily se lect multiple phase sequences by adjusting the background cycle length and progression speeds to find the optimal timing plans such as cycle green split phase se quence and offsets that can effi ciently maximize the two way progression bands 2 PASSER II 87 is the most re cently enhanced version of the PASSER II program PASSER II 87 microcomputer program Ver sion 1 0 was completed under the Texas HP amp R 2 18 86 467 study Enhancements to PASSER Il 84 by the Texas Transportation In stitute TTI of the Texas A amp M University System This new pro gram was designed for ready use by traffic engineers and transpor tation professionals to optimize or to evaluate the isolated signalized intersection or coordinated arterial street system of up to 20 signal ized intersections PASSER II 87 is a powerful easy to use and user friendly sig nal timing program for IBM PC XT AT 386 or compatible microc
31. ity to sustain all lateral soi pressures However soil movement is required to activate the reinforcement mem ber s tensile strength Research 3 at Glenwood Canyon Colorado indicates that less than 3 inches of lateral soil movement is necessary to stabilize a 15 foot high GRS wall in an unrestrained no abut ment condition Since one of the WHD objectives was to achieve an unrestrained condition no soil pressure on the abutment 3 inch thick polystyrene panels were placed between the geotextile and abutment or wing wall The pan els would compress with lateral soil movement and reduce or eliminate soil pressure against the abutment and wing wall CONSTRUCTION For both retrofitted and new structures the abutment and wing walls were used as forms for constructing each reinforced lift As shown in Figure 1 the founda tion soils were prepared by cutting a slope toward the abutment foot ing An underdrain system pipe and drain stone was placed bringing the fill height to approxi mately the height of the abutment footing top Three inch thick poly styrene boards were positioned on the soil side of the abutment and wing walls With the styrene in place the first geotextile layer was positioned The re embedment tail of the geotextile was tem porarily tacked to the polystyrene to allow subsequent fill placement and compaction Granular fill was then placed and compacted to a depth equal to one half
32. n still effectively start the system to solve signal timing and evalu ation problems The input output process helps users through the in teractive query with data input guidelines and sets of help menus in the data input process Routine data coding checks will help the users to modify the data without having to exit the PASSER II 87 system After all the input has been completed the system exam ines the input data automatically stores it in a data file executes the program and then allows the user to review or to print out spe cific output as needed PASSER II 87 Fig 1 com prises the most advanced micro computer technology with an intelligent user friendly menu in terface in the input output proces HPR 2 18 86 467 STUDY PASSER II 87 Al PROGRAM ON LINE HELP MENU SYSTEM REGULAR LINK GEOMETRY MAIN MENU EDIT MENU USE CURSOR KEY TO MOVE AROUND lt CR gt ORRETURN KEY lt SC gt TO TOGGLE SCREENS ALT C TO EXIT THE SYSTEM EMBEDDED NETWORK DATA INPUT DATA DATA SIGNAL SOLUTION PHASE EVALUATION DATA MENU SIGNAL WARRANT MENU INTERSEC PICTURE INPUT DISPLAY SCREEN MENU FIGURE 1 PASSER II 87 Microcomputer system menu Structure sor The system was developed so that it would accept all the exist ing PASSER IT or PASSER II 84 data without requiring any manual user modification The data can be entered or modified through either the full screen cursor keyboard Or mouse inte
33. nge To analyze an isolated intersec tion traffic turning movements and intersection approach satura tion flow rates are needed Mini mum phase times for each movement must also be provided PASSER II 87 can optimize the signal phasings ranging from the simplest two phase operations to the most complex variable se quence multiphase coordination The signal phasing is described on a permitted or allowed move ment basis Up to four possible arterial phasings are permitted at any one intersection whereas each cross street can have only one of four possible phase sequences In addition to the normal protected or permitted left turn phasing it can further analyze the complicat ed permitted protected or protect ed permitted combined phase left turn sequences The system employs the most advanced high way capacity technology There fore PASSER II 87 may also be used as a traffic planning or capac ity analysis tool if volumes satura tion flows intersection geometrics and signal timing are known 3 PROGRAM FEATURES PASSER II 87 has a complete stand alone microcomputer user interface for the interactive arterial progression and intersection capac ity analysis 1 It is an engineer ing tool that can be used to produce minimal delay and good arterial progression TTI and SDHPT have designed the microcomputer input output sys tem so that an engineer who is notz too familiar with a microcomputer ca
34. ntly reduced their bridge maintenance costs Since 1983 forty five Interstate State primary and State secondary structures have been constructed or retrofitted with geosynthetic reinforced soil GRS walls beneath each approach slab Geotextile inclusion enabled soil support continuance beneath the slabs and prevented or signifi cantly reduced lateral soil pres sures against the adjacent abut ment walls The result 1 not one of the 90 approach slab bridge deck junctions has required level ing to improve serviceability and safety and 2 none of the expan sion joints have required replace ment due to closure as a result of abutment movement PROBLEM IDENTIFICATION APPROACH SLAB Correcting bridge end bumps represented a costly maintenance program to the Wyoming Highway Department WHD For years the WHD addressed this problem by placing leveling courses above the approach slabs When required mud jacking was used to fill voids between a slab and embankment soil Both treatments offered limited success as con tinued maintenance was required at an annual cost of over 1 600 per bridge wherever the slab deck unconformity oc curred 1985 figure The continued drain on the Department s budget prompted an investigation to review alter natives The investigation con cluded that a method was required to prevent a loss in soil support beneath the approach slabs i e treat the cause of the pr
35. nts First the program will ask the user to provide the needed in formation concerning the use of the protected left turn bay for the corresponding left turn traffic movements Then the program will automatically generate the ap propriate treatments according to the user s input for the different left turn and through traffic move ments The intelligence imple mented in the PASSER II 87 program will allow the user to de termine the proper types of left turn signal treatments from their input The system will inquire and infer from the conditions in the following steps 1 Use traffic volume to dis tinguish the use of left turn bay 2 Use minimum phase time to indicate the use of protected left turn phases 3 Ask Is left turn protected only for the combined phase op eration and 4 Use the phase sequence to select which combined phase SYSTEM SUMMARY The PASSER II 87 Micro computer Environment System was developed by TTI for the Texas SDHPT to facilitate signal design and evaluation The system was developed for use on the IBM PC XT AT 386 or compatible microcomputer The new system has many advantages over the ex isting PASSER II 84 program be ing distributed 2 It provides a very user friendly menu interface full screen cursor movements and accepts all the existing coded PASSER II 84 data without re quiring user modification If de sired the user can freely modify 3 any embedded da
36. oblem as opposed to mending a surface con dition resulting from the problem Unfortunately the soil support loss had several origins among which were 1 densification of the embankment soils as a result of traffic vibrations 2 consolidation of the embankment soils and 3 piping of the embankment soils into the subgrade drain system or through joints or cracks in the structure Consolidation of the foundation soils was deemed negli gible due to their type and strength Therefore the remedial method had to address three ori gins of soil support loss After reviewing available alternatives GRS walls were chosen as the preventative measure based on reliability cost flexibility to account for site specific con straints and ease of installation PROBLEM IDENTIFICATION EXPANSION JOINT Expansion joint closure or reduced movement had been a troublesome and costly problem for the WHD At a replacement cost of approximately 25 000 for each device 1985 figure and a frequency greater than expected the WHD again reviewed the problem causes and available cor Vories rection alternatives Their review indicated that a contributing agent to expansion joint failure was abutment movement resulting from lateral soil pressure Since GRS walls could provide total lat eral soil restraint and were already planned for use beneath adjacent approach slabs they were consid ered the best solution to eliminate this origin o
37. omputers having the PC DOS or MS DOS 2 1 or higher diskette operating systems DOS The program requires a micro computer with a minimum of 512K RAM Random Access Memory and two double sided double density DS DD floppy drives or one double sided high density DS HD floppy diskette drive However it is highly recom mended that the program be used on hard disks for fast execution The system will be distributed to SDHPT personnel with the main program input preprocessor out put postprocessor optional help information and microcomputer user s manual for the PASSER II 87 microcomputer program system PASSER II 87 combines the updated version of PASSER II advanced analysis procedures simi lar to those in the 1985 Highway Capacity Manual and the latest microcomputer technology There are three major applications 1 isolated intersection timing evalu ations 2 progression signal tim ing Optimization and 3 Existing Timing Evaluation or Simulation Evaluation The program assumes the isolated evaluation as the de fault if the input data pertain to only one intersection On the oth er hand this program assumes progression if the input data in clude more than one intersection in the system In progression PASSER II 87 seeks to maximize two way bands and minimize sig nal delay based on the combina tion of traffic volumes saturation flows and minimum phase times under a given cycle length ra
38. on Flow 1800 pephgpl Analysis Period T 15 minutes LOS Delay Criteria A 5 M 65 Cc B 15 M 19 5 D 25 M 40 M Model Form Negative Exponential VO Opp Sat Flow T LTCriticalGap sec H LT Headway sec SL Exponential Function of VO T H vph 1750 FIGURE 3 STREET NAME Mockingbird 4 715 VOLUMES 568 43 SAT FLO 5250 1700 MIN PHS 16 10 el VOLUMES 88 SAT FLO 1700 MIN PHS 10 VOLUMES 287 SAT FLO 3500 a Total Delay P for Pretimed or A for Actuated PASSER Il 87 embedded data screen NEMA VEHICLE MOVEMENT Sneakers S 2 0 Phase Lost Time L 4 0 Left Turn P P A or R A Multiplier M 13 32 5 E 60 M 78 0 52 0 F gt 60 M 78 0 gt TexasA amp M Analytical Model lt Australian Analytical Model Univ of Texas Simulation Model Your Own Model Same Model Form INTERSECTION 1 a VOLUMES 1114 SAT FLO 3500 MIN PHS 21 6 ARTERIAL NAME Skiliman Avenue VOLUMES 51 1 5 SAT FLO 1700 MIN PHS 10 MIN PHS 21 r 71 N A VOLUMES 240 156 TRAFFIC VOLUME CALCULATION SAT FLO 1700 5250 MIN PHS 10 16 3 5 8 LT BAY NEEO VOLUMES SAT FLO MIN PHS LEFT TURN TRAFFIC PROTECTED PHASE OPERATION VPH 88 FIGURE 4 PASSER II 87 movement data screen all the embedded data in PASSER II if needed The default data Fig 3 have been prepared These embedded data include the traffic control type ideal satura tion flow rate an
39. rface The operator can exit the current state at any time by pressing the escape key The built in help windows are pro vided by pressing the FUNCTION KEY F1 OR F2 In addition users can even tailor the content of the global help screen according to their own agency specific re quirements through the use of the global PASSER Il 87 help menu by using the FUNCTION KEY F6 Two other utility functions like those available in many com mercial packages are also pro vided in PASSER II 87 to assist users in providing efficient traffic analysis The FILE DIRECTORY function can be reached at any time by pressing the FUNCTION KEY F4 for reviewing and pro viding the needed file manage ment More importantly the EXTERNAL DOS SHELL func tion can be activated by pressing the FUNCTION KEY F5 to al low users to reach the Diskette Operating System DOS com mand line interface level The user can perform all the file mainten ance functions such as formatting new diskettes backing up files and performing other analyses without even having to exit from the PASSER II 87 system PASSER II 87 provides an ex ceptional list of output features The output is headed by an echo of arterial parameters COVER a listing of system embedded data EMBED DATA an intersection input INPUT DATA and an er ror report ERROR MSG The optimized solution output provides a listing of the optimal timings for the arterial street
40. s Glenwood Canyon Colorado Transportation Re search Board Washington D C January 1983 4 Price John T and Sherman William F Geotextiles Elimi nate Approach Slab Settle ment Public Works Volume 117 No 1 January 1986 pp 58 59 EDITOR S NOTE The author of Geotextile Walls Reduce Bridge Maintenance Costs John T Price is a well respected civil engineer specializ ing in Geotechnical Engineering He presents either design or in formational workshops on geotextiles and geosynthetics The design workshops are geared pri marily toward project engineers The informational ones focus on giving a detailed introduction to the design and installation aspects of using geosynthetics If enough Departmental personnel express interest Mr Price could come and give a workshop on using geotextiles to reduce approach slab fill settling If you are inter ested in such a workshop call the TQ editor Kathleen Jones at TEX AN 241 7947 512 465 7947 and say so TROUBLESHOOTING HIGH RANGE WATER REDUCERS by Kathleen Jones D 10 Research Section Technology Transfer Group INTRODUCTION High range water reducers HRWR also known as super plasticizers are chemical admix tures which can be added to portland cement concrete mixtures to produce high slump concrete or to produce high strength above 6000 psi concrete depending on the mix proportions HRWRs increase workability by dispersing
41. ta for analysis D 13 TRAINING SCHEDULE SELECTED COURSES and the system will faithfully re port all the data used PASSER Level II Design II 87 has been enhanced tremen Session 1 Oct 3 7 dously to provide the graphical Session 2 Oct 24 28 traffic input and the ASSIS Session 1 Nov 14 18 TANT function to help users Session 2 Dec 5 9 with the 1985 HCM capacity ana lysis The system can analyze all Call Mr Ron Petter D 13 TEX AN 241 3093 512 465 3093 for more information on Design courses the commonly available left turn signal treatments either with or Construction Inspection without protected left turn phases Introduction to Construction Inspection 1 Nov 14 18 or protected left turn bays The Advanced Bridge Construction Inspection Dec 5 9 system can also investigate the Hot Mix amp Concrete Construction Inspection Dec 11 16 Operational effects of the com bined phase i e protected plus permitted or the permitted plus protected left turn signal phasings The new system provides an improved scheme for allowing the input of the existing or user selected offsets for arterial capac ity evaluation The system will provide the user with the im Call Mr Dell Wood D 13 TEX AN 241 3094 512 465 3094 for more information on Construction Inspection courses The mentioning of brand names used is strictly for informational purposes and does not imply en
42. the dis tance between the reinforcement layers except immediately adja cent to the abutment and wing walls At these locations the full depth of fill between geotextile layers was placed The embed ment tail was then positioned and the remaining fill added to achieve proper elevation to the level of the next geotextile layer This embedment tail tucking procedure was used to enhance geotextile to soil friction and thus reduce the possibility of a local reinforcement member pull out failure The sequence of geo textile fill placement was repeated until the approach slab elevation was achieved COSTS AND BENEFITS INVOLVED 1985 FIGURES Once the foundation soils were prepared the installed cost of the geotextile reinforced system was approximately 12 000 per bridge or 6 000 per end For com parison a conventional un rein forced approach slab embankment typically costs approximately 3 200 The 2 800 difference was attributed to additional granular fill requirements and geotextile costs as well as increased construc tion time requirements Justification for this initial capital outlay resulted from elimi nation of the 1 600 annual main tenance cost for leveling at many locations Public conve nience and increased safety contributed significantly to offset the cost differential Finally the elimination of the replacement of just one explansion joint offset the increase in construc
43. tion cost of eight GRS walls Therefore geosynthetic reinforced soil walls were considered justified and have become the design alternative pre ferred by the Wyoming Highway Department for approach slab embankments CONCLUSIONS Forty five Wyoming bridges 90 approach slab embankments have been constructed or retrofitted with geosynthetic reinforced soil walls since 1983 The structures h 6 have withstood a wide range of internal and traffic loadings Since the installation of the GRS walls the Wyoming Highway Depart ment has not made repairs to any of the 90 embankments or ap proach slabs as a result of soil support loss Similarly the State has not been required to replace any expansion joints associated with these bridges COMMENTS The use of geosynthetic rein forced soil walls is an effective means to reduce approach slab and expansion joint maintenance costs The Federal Highway Administration and U S Forest Service as well as many State transportation departments recog nize GRS walls as a genuine tool for use by engineers Since the ini tial WHD installations and the subsequent cost figures reported previously more realistic less conservative analytical tools are now available which reduce the strength and embedment lengths of the reinforcement members Therefore significantly lower cost walls may be constructed Geo synthetic reinforced embankments may be properly constructed by contr
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