1. IDENTIFYING MAT FAULTS
Reading the Mat
IDENTIFYING MAT FAULTS
TAKING THE CORRECT REMEDIAL ACTION

2. Too Many Experts!
They Cause Confusion
& Make a Mess of Things

3. Reading the Mat Mission Statement
“Produce a Blemish Free Mat Free From Lines (Steps), Streaks, Dragging (Tearing), Segregation, and/or Texture Differential.”

4. Identifying Blemishes in the Mat
Reading the Mat
Identifying Blemishes in the Mat
Terminology:
- Severe Marks
- Texture Differential
- Segregation
- Steps,Miss Matched Lines
- Voids
- Streaks
- Dragging (Tearing)
- Crushing Aggregate
- Cracking

5. SEVERE MARKING OF THE MAT
READING THE MAT
SEVERE MARKING OF THE MAT

8. Counter this with Screed Lock
Mat Marks
Counter this with Screed Lock
When Paver Stops:
Screed Weight Becomes the Dominant Factor

9. Showing up on Profilograph
READING THE MAT
Severe Mark in Mat
Showing up on Profilograph
Cause
1. Paver stopped due to lack of material
2. Roller stopped too close to paver
Remedy
1. Good material delivery
2. Minimize paver stops
3. Balance paver & roller speeds with material delivery
4. Roller to stop on previously compacted mat

10. Texture differential caused by screed extensions being too high.
Known as
‘Double Screeding’

11. Shadow

12. Shadow Problem

13. Mat quality beginning to change

14. Left side mat quality greatly improved

15. Mat quality on completion

16. Mat quality on completion

17. READING THE MAT Cause Remedy 1. Adjust extension height Mat Shadows
(Texture differential)
Cause
Uneven distribution of screed weight over mat area
Remedy
1. Adjust extension height
2. Decrease angle of attack of extensions

18. SEGREGATION THROUGH THE PAVER
READING THE MAT

19. Cool mix is being segregated by the augers

20. Segregation & cooling is caused by multiple handling of the material

21. Segregation through paver
READING THE MAT
Segregation through paver
Cause
1. Poor material
2. Use of pick up machine with no hopper insert
3. Material breaking up in augers
Remedy
1. Avoid segregation at plant during loading
2. Dump material en-masse in to hopper or use MTV with hopper insert
3. Keep hopper full, set flow gates and augers at optimum position
4. Refer to road institute/NAPA publications

22. CENTER LINE STREAKING
READING THE MAT

24. Any paver with a center drive auger box may cause center line streaking when using certain materials
Adjustment must be made to the tractor and the screed to eliminate these marks

25. Insufficient material getting under auger drive box
READING THE MAT
Center line streak
Cause
Insufficient material getting under auger drive box
Remedy
1. Raise augers & flow gates
2. Check condition and position of kick back auger flights
3. Adjust side arm to rearmost position at tow point to move screed further back

26. STEPS OR SCREED MARKS IN MAT
READING THE MAT

32. Stone caught at screed causing dragging of the mat
What’s wrong here ?

33. Forward Mounted Extensions
What's Wrong?
EXTENSIONS TOO HIGH!

34. Front Mounted Extensions
What's Wrong?
EXTENSIONS TOO LOW!

36. Rear Mounted Extensions
Extensions Too High!
What's Wrong?

37. Rear Mounted Extensions
Extensions Too Low!
What's Wrong?

38. 2. Extension Angle of Attack
What's wrong?
1. Cold Extension
2. Extension Angle of Attack

39. What's wrong?
Transition Lines Made by Extension Being Incorrectly Set to Main Screed

40. Incorrectly set up screed or screed twisting
READING THE MAT
Steps or lines in mat
Cause
Incorrectly set up screed or screed twisting
Remedy
1. Ensure screed is set up up correctly prior to work starting
2. Adjust screed as necessary on the fly
3. Be aware of your screed gauges
4. Do not chase lines that come and go

41. HOLES OR VOIDS IN THE MAT
READING THE MAT

44. READING THE MAT Holes in the mat Cause
Hopper running out of material between truck loads
(head of material fault)
Remedy
Keep hopper 30% full at all times
Install material level indicator kit

45. INSUFFICENT THICKNESS OF MATERIAL
READING THE MAT
DRAGGING AND TEARING
&
INSUFFICENT THICKNESS OF MATERIAL

48. Dragging & Crushing rock through laying too thin

49. Maximum Thickness Approximately
Angle of Attack Too Low
Maximum Thickness Approximately
4 to 5 x Nominal Rock Size
Minimum Thickness
1.5 to 2 x Nominal Rock Size
(3 x For Superpave)
Mat Dragging & Crushing Rock
Due to Insufficient Angle of Attack
Base or Lower Surface

50. READING THE MAT Dragging and tearing of the mat & crushing rock Cause
1. Cold screed
2. Paving speed
3. Poor material quality
4. Laying too thin
Remedy
1. Heat screed correctly to the desired temperature
2. Reduce paving speed
3. Have plant check out material quality
4. Increase angle of attack

51. READING THE MAT SUMMARY
Whenever a fault appears in the mat, trace it back to the screed and tractor and investigate the cause.
Consider screed operation and adjustment, paver operation, set-up or adjustment, material quality and temperature and foreign objects.
Determine the cause and take the correct remedial action.