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Chip Seals. 1.List the purposes of chip seal applications 2.Describe different chip seal variations 3.Describe recommended materials 4.List the steps.

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Presentation on theme: "Chip Seals. 1.List the purposes of chip seal applications 2.Describe different chip seal variations 3.Describe recommended materials 4.List the steps."— Presentation transcript:

1 Chip Seals

2 1.List the purposes of chip seal applications 2.Describe different chip seal variations 3.Describe recommended materials 4.List the steps of the chip seal design process Learning Outcomes

3 5.Describe recommended construction procedures 6.List key quality control activities 7.Describe potential construction and performance problems 8.Identify associated solutions Learning Outcomes (cont.)

4 Introduction Description Application of asphalt binder on existing pavement followed by a layer of aggregate chips. The treatment is then rolled to embed the aggregate into the binder. Commonly used on low-volume roads

5 Surface for light to medium traffic Waterproof layer Skid resistant surface Restore weathered surface Address bleeding Temporary base course cover Define shoulders Project Selection

6 Limitations Structurally deficient pavements Cracks >6 mm (0.25 in) wide Medium- to high-severity alligator cracking Large number of potholes Rutting >25 mm (1 in) Very rough surface

7 Performance and Cost Performance –Proper application of binder and aggregate –Proper embedment –Typical treatment life: 4 to 7 years Average cost –$0.96/m 2 to $1.32/m 2 ($0.80 to $1.10/yd 2 )

8 What a Chip Seal Can & Can’t Do A Chip Seal CAN: Seal the surface of a roadway Restore or improve skid resistance Preserve a good road for 5 to 10 years A Chip Seal CAN’T: Increase the strength of a roadway Restore a failed roadway

9 Chip Seal Variations Single chip seals Double or triple chip seals Cape Seals Sand seals Fabric and chip seals

10 Chip Seal Variations Single Chip Seals Existing Pavement Pneumatic- Tired Roller Binder 70%

11 Chip Seal Variations Double Chip Seals Existing Pavement Binder Pneumatic- Tired Roller Second Binder Application Pneumatic- Tired Roller

12 Chip Seal Variations Cape Seals Existing Pavement Pneumatic- Tired Roller Binder Slurry Seal Brooming

13 Chip Seal Variations Sand Seals Existing Pavement Pneumatic- Tired Roller Binder

14 Chip Seal Variations Fabric and Chip Seals Existing Pavement Tack Coat Paving Fabric Binder Applicatio n Pneumatic- Tired Roller

15 Chip Seal Variations Fabric and Chip Seals

16 Material Selection Binder

17 Rapid setting emulsions Polymer-modified emulsions Asphalt cement Rubberized asphalt

18 Asphalt Water Emulsifying agent (surfactant) Material Selection Emulsion Ingredients

19 Emulsion Nomenclature CRS-2P CATIONIC HIGH VISCOSITY POLYMER MODIFIED RAPID SETTING

20 Material Selection Emulsion Classification Electrical charge (+ or – ) Speed of break: slow (SS), medium (MS), and rapid set (RS) Asphalt relative viscosity: hard (h) or soft (s) Polymer-modified asphalt (P or L) High float (HF)

21 What is “AC” Asphalt Cement? Hot applied asphalt binder Generally graded by viscosity Typically modified with polymer or tire rubber to improve qualities

22 Asphalt Cement Nomenclature AC-15P ASPHALT CEMENT 1,500 + VISCOSITY POLYMER MODIFIED

23 Emulsion Type Slow Setting Medium Setting Rapid Setting AnionicSS-1 SS-1h MS-1 MS-2 MS-2h HFMS-1 HFMS-2 HFMS-2h HFMS-2s RS-1 RS-2 HFRS-2 CationicCSS-1 CSS-1h CMS-2 CMS-2h CRS-1 CRS-2 Material Selection Emulsion Classification

24 Time depends on temperature and relative humidity Emulsion break should begin just after first roller pass Curing of Binder

25 Material Selection Rubberized Asphalt Chip Seal

26 Material Selection Aggregates Clean and durable One size : 6 to 16 mm (0.25 to 0.6 in) Cubical shape Flat and elongated particles limited to 25 to 30 percent Fines limited to 1 to 2 percent

27 Aggregate used for a chip seal

28

29 Grade 3 crushed limestone, Colorado Materials Co.

30 Grade 3 crushed limestone, asphalt coated, Colorado Materials Co.

31 Grade 4 crushed limestone, Colorado Materials Co.

32 Grade 4 crushed limestone, asphalt coated, Colorado Materials Co.

33 Grade 5 crushed limestone, Colorado Materials Co.

34 Type L, Grade 3 expanded shale aggregate, TXI

35 Type L, Grade 4 expanded shale aggregate, asphalt coated, TXI

36 Type L, Grade 5 expanded shale aggregate, TXI

37 Grade 3 crushed limestone rock asphalt, Vulcan Co.

38 Grade 4 crushed limestone rock asphalt, asphalt coated, Vulcan Co.

39 Existing Pavement Pneumatic- Tired Roller Binder Material Selection Problem With Flat Aggregates Cracks in Aggregate

40 Chip Seal Design Process Assess existing pavement Select chip seal variation Select compatible binder and aggregate Quantity selection

41 Design Considerations Quantity Selection Residual asphalt content –Asphalt cement factor = 1.0 –Emulsion factors range = 0.55 to 0.65 Aggregate application rate –Single chip layer –No more than 10% excess chips –70% embedment recommended

42 Chip Seal Design Methods McLeod procedure Asphalt Institute (Table in the Reference Manual)

43 Asphalt Institute Method 1.Determine aggregate size and specific gravity 2.Aggregate and asphalt emulsion quantities from table 3.Adjust aggregate (if necessary) 4.Adjust asphalt content based on condition of road (if necessary)

44 5 Keys to Success Repair old surface ( days ahead) Calibrate equipment prior to use Inspect surface to determine rates Choose the right materials Timely application of asphalt and aggregate

45 Construction

46 Construction Conventional Chip Seal Procedure 1. Clean existing pavement 2. Apply binder 3. Spread aggregate 4. Roll 5. Allow binder to cure 6. Broom loose aggregate

47 Construction Cleaning Existing Pavement

48 Construction Start and Stop Application on Mat

49 Construction Binder Application

50 Spray Bar and Nozzles Single Overlap Construction Binder Overlap h h Roadway Surface Double Overlap Roadway Surface Triple Overlap Roadway Surface h

51 Construction Binder Application Overlap Triple Overlap

52 Construction Binder Application

53 15 o 45 o 90 o Travel Direction Lateral Coverage Binder Application Asphalt Distributor—Spray Nozzles

54 Construction Aggregate Application

55

56 Immediate rolling of aggregate Pneumatic-tired rollers No fewer than three passes Full coverage necessary before asphalt hardening Construction Rolling

57

58

59 Time depends on temperature and relative humidity Emulsion break should begin just after first roller pass Open to traffic in about 2 hours Construction Curing of Binder

60 Construction Brooming Loose Aggregate

61 Project review Document review Material checks Quality Control Preliminary Responsibilities

62 Surface preparation Equipment inspection –Asphalt distributor –Chip spreader –Haul trucks –Rollers –Brooms Quality Control Pre-Application Inspection

63 Weather requirements Determining application rates Checking application rates Traffic control plan and setup Quality Control Pre-Application Inspection (continued)

64 Asphalt application Aggregate application Truck operation Rolling Longitudinal joints Transverse joints Brooming Quality Control Project Inspection

65 Cleanup Opening to traffic Quality Control Post-Application Inspection

66 Quality Control Plan Class groups: preliminary responsibilities, pre-application inspection, and project inspection Label QC items as Always Included, Sometimes Included, or Frequently Omitted Use Reference Manual and your experience

67 Chip Seals QUESTIONS?


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