TRACKLESS TACK/ SPRAY PAVERS

Transcription

1 TRACKLESS TACK/ SPRAY PAVERS Jerry Peterson - CST

2 Table of Contents 1 Trackless Tack - Overview Research Pulloff Test Research Tracking test Trackless Tack Tips Spray Paver - Overview Best Practices

3 What is Trackless Tack Tack coat applied ahead of laydown operation How does it work? Cures or hardens to a non-sticky surface Reduces pickup on equipment Mix melts the hardened tack to create a bond Superior Bonding? 3

4 Specifying Trackless Tack Lots of different products out there Emulsion/hot applied Time to become track free Amount of residue Dilution Rates Writing a spec is difficult Can t encompass all properties and still be meaningful Would like to have performance spec May use MPL strategy in short term 4

5 Varieties Property Trackless Tack Ultrafuse MOS-50 FastSet NanoTac E-Tac Saybolt Viscosity 15 min n/a Storage stability, 1-day 1% n/a 1% settlement Settlement, 5-day 2%-5% n/a Sieve test 0.3% n/a 0.1% Track free time Residue Dilute? No No?? 40% 50% No Test on residue: Residue Pen 20 max 25 max 12 max Min Solubility Min Soft point Min DSR, 82 C Min 275 F 3000 Viscosity APPLICATION RATE

6 Performance Based Spec? What behaviors are important to trackless tack materials? Track-free Good bond Try to devise tests to identify these behaviors Pull-off test Paint pickup test 6

7 Direct Tensile Bond Test: ASTM C

8 2 inch diameter cores to just below interface 8

9 Ready to Pull Off 9

10 After Pulloff Clean break at lower interface 10

11 Pulloff Experiment Summer C High 0.1 High 0.1 High 0.1 High 0.12 High 0.12 High 0.08 High 0.20 High 0.18 None Low 0.04 Low 0.04 Low 0.06 Low 0.08 Low 0.10 Low 0.05 Low 0.12 Low 0.08 Mono Res Res Res 63.3% Res 64.3% Res 62.0% 65% 40% 61.5% 50% Res 58.0% Res 64.3% Res 100.0% diluted diluted 11

12 Pulloff Experiment Summer 2013 Average pulloff loads at 4 C Peak Load (lbf) A B C D E F G H No Tack Monolithic 12

13 Tracking Test - ASTM D711 13

14 Summer Tracking Test Results ASTM D 711 No Pickup Time Track Free Time (min) SS-1H CSS-1H CRS-2P A B C D E 14

15 Research Bottom Line Needs more work Results were not very conclusive Tracking test may not be severe enough Performance based spec won t be ready right away Need to use vetted products! MPL Required successful demos 15

16 Trackless Tack Coat: Tips for Use Know which product you have Communicate with the vendor Handling/dilution Application rates are critical! Shoot a test strip Even application Check for tracking 16

17 Austin District Practice Do not apply trackless tack like a seal coat asphalt More like a fog seal operation Do not shot asphalt perpendicular to roadway Will streak Non-uniform Too heavy in area will pick up Too light in areas will not bond 17

18 Austin District Standard Use fogger nozzles Every 3 feet Shot parallel to the roadway surface Use a 90 degree elbow to fix nozzle parallel Creates a misting of the surface Should look like the surface is spray painted black 18

19 Spray Paver 19

20 What is a Spray Paver? 20

21 The Paver 21

22 The Paver 22

23 How Does it Work? Spray-bar Mix 23

24 Things to Watch For Look for an even distribution of emulsion and a consistent texture and color behind the spray bar Make sure emulsion breaks properly Be careful of fat spots Paver sitting without tray recirculating Problem with nozzle High spot in the pavement surface 24

25 Watching the Spray Pattern 25

26 Best Practices Avoid start and stop paving Can give inconsistent membrane application Paver can refill on the fly Keep a clean lane out ahead Don t want mix on the pavement before membrane Mix falling off of trucks 26

27 Thanks! Spray paver info/materials Robert Lee Austin District tack info Mike Arellano 27