Spessard, Tom

English

Purdue E-Pubs

Cracking and Seating Concrete Pavem ent on I -74 Part I I—C onstruction Conditions and M ethodsT om S pessard Project E ngineer Craw fordsville D istrict, ID O HC racking  and  seating operations on I -74 began on Ju ly  10, 1984, with section 474 +00-768 +00. This section was com pleted A ugust 17, 1984. A second section, 924 + 77-1050 + 00, was started O ctober 3, 1984, and com pleted O ctober 4, 1984.O n this project several im pact spacings and energy levels were tested on different pavem ent sections, varying the num ber of blows and a lte rn ­ating  the spacings. V ery little surface spalling occurred as long as the proper im pact angle was m ain tained.Along different patterns three different m achines were tried, namely; whipham m er, arrow-type pavem ent breaker, and W irtgen D rop-H am m er or guillotine type.Also in one area relief jo in ts were cut to see if expansion of pave­m ent, due to high tem pera tu re , m ade it m ore difficult to induce the desired cracking patte rn .T est sections were used to assure that the desired patte rn  was achieved. C onditions to note in setting up patterns and test areas are: pavem ent condition, thickness, and type of reinforcem ent, if any, as well as existing conditions such as surface spalling, weakness, and existing cracks.W hen pavem ent conditions change, check sections should be observed to see that the desired patte rn  is achieved and unnecessary pavem ent dam age is lim ited.M ethods of checking pattern:1. Sprayed or m isted w ater on surfaces shows cracks as the w ater dries. Early m orn ing  light and rainshow ers m ake the cracks show best.2. The use of flour was suggested by the equipm ent supplier. Flour is spread on the pavem ent then broom ed to an even dusting. W hen the m achine strikes the pavem ent, the flour moves away from the cracks and highlights them .W hile different patterns and m achines were being used cores of pave-107m ent were taken in series to show how cracks traveled through  the pave­m ent slab.All du ring  the cracking and seating, operation  tests were m ade with the dynaflect, before and after cracking. After each pass by a 50-ton roller, and after testing several areas, it showed that three passes by the roller achieved all the seating possible on this project.T he roller used by the contractor on this job  was a single-axle roller with a 4000 gal capacity. It was pulled by a rubber-tired  dozer. T he tank of the roller was filled with aggregate m aterial, then soaked with w ater to achieve the desired weight. T his m ethod worked well especially for m oving across bridges; the contractor would unload part of ballast on one side of the bridge and reload at the desired location.Because cracked and seated sections could be com bined with s tan ­dard  overlay sections, four-m ile sections of pavem ent were worked at a tim e.At tim es, during  operation, traffic was placed on cracked and seated pavem ent areas before they were overlayed. O n  this project, areas sub­jected  to traffic showed no additional spalling or dam age and m a in ta in ­ing traffic flow was not a problem .D uring  the cracking and seating operation  the dynaflect was used each day. At that tim e, with the cooperation of M oellering, the dynaflect was carefully worked in com bination  with the cracking and seating p ro ­cess in an attem pt to find out w hat was happening  to the pavem ent th roughout the process, as well as the m ost effective num ber of passes to atta in  the best slab seating. T his was done by m arking a 100-foot test section into ten test stations. Each station was then tested with the dynaflect before cracking, after cracking and before rolling and after each single pass of the roller. R olling and testing was continued until it was felt that m axim um  seating had been achieved. In most cases, rolling more than one pass did not provide significantly bette r seating and too m uch rolling was, as expected, detrim ental to seating; seating im provem ent was not near w hat we had originally expected. D ue to these findings most of the contract has been rolled the specification m in im um  of three passes. W e also found that the areas that had carried  traffic after the cracking and seating process, and before the overlay, showed a small seating im provem ent over areas that were overlayed im m ediately after cracking and seating.A nother experim ental feature added to this project was the use of a polypropylene fiber-reinforced asphalt. In O ctober 1980 the Crawfords- ville D istrict placed a T ype A fiber-reinforced surface on a portion of I -65 at the intersection of SR-43. T he ou tstand ing  perform ance of this test pad prom pted the ID O H  to exam ine this m aterial on a larger scale. W e had originally p lanned to place the m aterial on a section of C R C  on I -65 ju st south of Indianapolis, how ever, due to some conflicts w ithin108the departm en t it was rem oved from that project and added to this p ro ­ject. T he objectives are to determ ine the benefits gained by the introduc­tion of fibers into the mix, m ainly to determ ine w hether or not the fiber can reduce cracking and control ru tting .Following are the construction details for this portion  of the project.F iberm ix b itum inous overlay laps over both a standard  overlay sec­tion and a cracked and seated section on this project.A pproxim ately 4780 tons of the mix were applied to both base and binder. T he plant used by the contractor was a drum -m ix  type. T he addition of fiber seemed to help segregation especially in the #5 base and gave a m ore even looking m at texture. Fiber-reinforced m aterial also showed less signs of raveling on tapers when subjected to traffic.B inder-lay with fiber looked tighter, as if it had  m ore fines. As far as placing m aterial, apparen t differences were not noticed except m aybe there was slightly less roller im prin t. At the present tim e all base and b inder operations are complete with only m iscellaneous operations such as grading and approach work. T he Type IV  Sand Surface will be com ­pleted next year. T he contract has a calendar com pletion date of N ovem ber 1985, but it should be done by m id-sum m er.109

Cracking and Seating of Concrete Pavement on I-74 Part II - Construction Conditions and Methods

https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=3505&amp;context=roadschool

Cracking and Seating of Concrete Pavement on I-74 Part II - Construction Conditions and Methods

Abstract

Similar works

Full text

Available Versions

Purdue E-Pubs