2014 APC/ Dist. 9-0 BITUMINOUS PAVING

Transcription

1 2014 APC/ Dist. 9-0 BITUMINOUS PAVING

2 To Be Covered- BLUE KNOB MC PILOT SPECIAL PROVISIONS TACK COAT LONGITUDINAL JOINT PERCENT WITHING TOLERANCE (PWT) SPEC LOCAL ACCEPTANCE- RETESTS SAFETY EDGE

3 Importance of Tack

4 So why use tack coat? Without tack coat the asphalt layers in a roadway may separate which reduces the structural integrity of the road and may also allow water to penetrate the structure. Proper tack application rates and material creates a composite pavement section, transferring stresses throughout the entire paving section. A good bond is important for all mixes, & has a large affect on mix performance. 4

5 So what s changing? Pilot project using CSS-1h (E-8) emulsion Looking at improving bond strength using harder based asphalt. Considerably less break time (about ½ the water Vs. AET) Less pick-up by paving train equipment due to harder base asphalt More uniform coverage, with application rates specified

6 District Special Provision for all Paving Projects Tack Coat Special Provision

7 So what s the cost? CSS-1h (E-8) has about twice the asphalt Vs. AET Costs about 69% more per Gal. of emulsion Example: 1 mile 32 wide (18,775 SY) Using 0.03 Gal/Sy Residual Would use 1706 Gal of $1.38/Gal= $2,355 Using 0.03 Gal/Sy Residual Would use 908 Gal of $1.99/Gal= $1,807 Savings: Approx. $550 per 2-lane mile Uses approx. 800 gal. less emulsion

8 Tack Summary- Spec. Changes- Material will be CSS-1h (E-8). Specified residual application rates for surface type 100 LF min. test section to verify application rate, bar height, nozzle function & proper overlap and orientation. Surface Type Uniform Asphalt Residue Application Rate (gallons per square yard) New HMA pavement course 0.02 to 0.03 Existing HMA pavement course 0.03 to 0.05 Milled Surface (HMA & PCC) 0.05 to 0.07 Portland Cement Concrete (PCC) 0.04 to 0.06

9 Tack Summary- Benefits- Seen from switching to CSS-1h (E-8) Increased bond & shear strength - Composite section Much quicker break time, less waiting Less puddling and run-off Less tracking by equipment Uses less Liquid material (about 53%), less hauling

10 Longitudinal Joint Pilot Special provision to assist in achieving better joint density (non-incentive) Requires nuke readings at min. 500 Correlation cores if mat is not using cores for density acceptance Information cores required 6 from joint if mat is accepted using density cores Cores run at producer s lab Stop paving operations if lot avg. < 91% Provide corrective action prior to proceeding with paving operations

11 Longitudinal Joint Pilot Currently in Clearance Transmittal review to become a State Std. Special Prov. Longitudinal Joint Spec.

12 Percent Within Tolerance (PWT) Pilot project using a pure PWT spec Payment factors for four criteria AC Content #200 Sieve Primary Control Screen (PCS) Density Each pay factor evaluated statistically for spec limits Up to 4% bonus available to contractor Less Harsh penalty structure Eases R&R s Samples tested at LTS Directive from FHWA to move in this direction

13 Percent Within Tolerance (PWT) So, how it went Lot #1, 25 mm Base (Info only) Incentive = 2% Bonus Lot #2, 9 mm Wearing Incentive = 1% Bonus Lot #3, 9 mm Wearing Incentive = 4% Bonus High Accuracy but low precision High Precision but low Accuracy

14 Percent Within Tolerance Contractor s View (PWT)

15 Local Acceptance What s Changing Retest requests will be permitted and reviewed as follows: Retests may be requested for material failures (Asphalt & No. 200), resulting in remove and replace only. Retests for density are not permitted. If the retest request is approved, testing will be performed by the Department utilizing the Local Acceptance Testing location identified in the approved QC Plan. Applies to Superpave and SMA utilizing Local Acceptance

16 FHWA Everyday Counts Safety Edge- Issues: Adjusting paver- Driveways, Structures, etc Stopping paver to switch between Wedge and Safety Edge Rural areas Lack of available shoulder, guiderail, etc Prep work/ lack of Others?