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Marquette Universitye-Publications@MarquetteTransportation Research Center: Noise & TextureStudies Transportation Technical Reports1-1-20012001 WisDOT Specifications - Texture of PCCPavementsMarquette University, Transportation Research Center2001 WisDOT Specifications - Texture of PCC Pavements. Madison, Wisconsin, Department ofTransportation (2001)._____Series Collection:2001 WisDOT Specs - Marq Staff Introduction2001 WisDOT Texture of PCC Pavements (Current Page)2001 WisDOT Construction NotePage 8.10-1 Revised 6/01State of Wisconsin                                                Department of TransportationChapter 8 Concrete Pavements8.10 TEXTURINGSubsection  415.5.9.6 of the standard specifications provides that pavements with adesign speed of less than 40 MPH (65 km/h) receive an artificial turf drag texture.Pavements with a design speed of 40 MPH (65 km/h) or greater receive the turf dragtexture, followed by a machine-applied transverse tining.The finish imparted to the pavement by the turf drag and/or tining machine is very criticalfor safety. High skid resistance is necessary for motorists to maintain control of theirvehicles under slippery conditions. Properly textured and tined pavements can help savelives.Artificial turf is dragged longitudinally over the pavement behind the finishing machine.The drag should produce a good longitudinal microtexture, but should not tear thesurface. If it is not producing a good microtexture due to slumping fresh concrete, thecontractor should move the drag away from the finisher. If the surface is tearing, thecontractor should move the drag closer to the finisher. Pressure on the concrete can be increased by lengthening the drag in contact with thepavement, or decreased by shortening the drag. Usually 3 feet (1 m) to 5 feet (1.5 m) arein contact with the surface. Check the drag material before paving and from time to timeduring finishing for tears, worn surface, or hardened concrete. The contractor shouldclean or replace the drag as often as necessary to maintain a well defined microtexture.The turf drag should not be applied when the surface is so wet or plastic that the ridgesformed flow back into the valleys when the drag has passed, nor should dragging bedelayed until the concrete is so hard that sharp ridges cannot be formed by the drag.Surface conditions may not be fully uniform, however, and dragging should be timed tomaximize skid resistance. The contractor should not pull the drag ahead with the finishingequipmentThe inner and outer 6 inches to 12 inches (150 to 300 mm) of the slab should be handdragged to prevent edge slumping or tearing. An acceptable broom finish can be appliedto small areas of pavement or driveways where a turf drag cannot be operated.The turf drag is followed by a tining machine that drags a steel rake transversely acrossthe slab to produce macrotexture. This macrotexture improves wet pavement friction byproviding escape channels for water trapped under vehicle tires. Transverse tinedpavements, particularly those with uniform tine spacing, may however produce anobjectionable tire/pavement whine.A WisDOT research study conducted by Marquette University demonstrated that skewedtransverse tining, with a random tine spacing, minimizes whine without sacrificing friction.Wisconsin Department Of Transportation CONSTRUCTION AND MATERIALS MANUALPage 8.10-2 Revised 6/01The Marquette study also recommended using a 10-foot (3.022 m) rake with randomlyplaced tines to avoid repeating tine patterns over the typical passenger car's wheelbase.Based on the Marquette study, subsection 415.5.9.6.3 of the standard specificationsrequires the following computer generated random tine spacing for a 10-foot (3.022 m)rake:Tine Spacing (Center to Center of Tines, mm):34 36 47 54 48 43 32 31 27 36 29 4621 43 23 42 52 24 18 28 40 34 27 2625 27 20 37 38 52 51 45 37 43 53 1427 37 42 41 29 43 14 45 44 30 37 3340 28 31 50 34 45 15 20 45 50 16 5351 29 25 18 16 53 18 38 51 40 17 1549 50 39 51 36 36 38 46 29 38 50 2433The specification also allows hand tining of areas such as ramps, gaps, intersections,etc. where machine tining is not practical. In these areas it may be difficult or impossibleto maneuver the tining machine, or the machine may be in use elsewhere on the projectwhen these areas are poured.The contractor has the option of skewing or not skewing the tining. Because skewedtining is quieter, the contractor should be encouraged to use skewed tining. Whicheverpattern the contractor selects, make sure that pattern is used consistently for all the areasrequiring tining on the project. If joints are skewed, the tining must either be skewed in theopposite direction or not skewed at all.The rake should be checked for missing, bent, or broken tines before tining. Also checkthe tine spacing and make sure the tines are clean. The specification is based on thedimensions of the rake not the spacing of the grooves created in the pavement. Theflexible tines cause variability in the spacing of the grooves created in the pavement andthus make it impractical to measure the groove spacing. If the rake is constructed asspecified and well maintained, the pavement grooves should have the desirable randomspacing between 3/8 of an inch (10 mm) and 2 1/4 inches (57 mm). If the pavementconsistently shows spacing outside these limits, examine the rake for problems.During the tining, check the concrete grooves for uniform depth within the limits specifiedin 415.5.9.6.3 of the standard specifications. If the surface is tearing, the contractorshould decrease the transverse speed of tining or move the tining machine closer to thepaver. If the groove is slumping, the concrete is not stiff enough, the contractor shouldmove the tining machine away from the paver. If the grooves are not deep enough, thecontractor should adjust the machine or move it closer to the paver.The timing of the tining operation must be coordinated with the dragging operation andadjusted for conditions to produce a uniform depth of sharp, well defined grooves. Thefinished surface should be free from rough or porous areas, irregularities, anddepressions resulting from improper handling of the tining machine.

2001 WisDOT Specifications - Texture of PCC Pavements

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2001 WisDOT Specifications - Texture of PCC Pavements

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