Chip Seal Best Practices (2005) / Chapter Skim
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Pages 60-63
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From page 60... ...
Most use both in-house and contract crews to apply their chip seals and achieve satisfactory results with both types of crews, although 10 of 13 agencies believe that in-house seals produce a better final result. The major distress observed with the in-house chip seals is bleeding, especially at intersections, and the major distress observed with contract chip seals is early loss of aggregate.
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From page 61... ...
The impression that one gets from looking at these tables is that all the agencies that reported excellent chip seal performance appear to not only have introduced a high degree of prescriptive specification into their programs, but they also are using the benefits that can be accrued by the advances in material science, such as the use of modified binders, robust 62 QC testing programs, and state-of-the-art construction equipment in their chip seal programs. One also notices that there is very little difference between those agencies that restrict chip seal usage to lower-volume roads and those that routinely use the system on high-volume roads.
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From page 62... ...
and 3/8 in. Design Method Individual Kearby Empirical Design Done By In-house maintenance engineer No response In-house design engineer Design Method Usage 13 years 10 years 30 years Distress Level of Underlying Surface Moderate Moderate Moderate Structural Condition of Underlying Surface Good Fair Fair Computerized Control Required on Distributor/Chip Spreader Yes/Yes Yes/No Yes/Yes Specified Controls on Rolling Number of passes and maximum speed Roller weight and maximum speed Roller weight Traffic Control Measures Reduced speed, interim pavement markings, flaggers, pilot cars Reduced speed, interim pavement markings, flaggers, pilot cars Reduced speed, interim pavement markings, flaggers, pilot cars Time to Open to Reduced Speed Traffic 10 min 4 h As soon as possible Aggregate QC Tests % fracture Flakiness Anti-strip Presence of clay Gradation X X X X X X X X X X Methods to Maintain Seal after construction Crack seal Chip seal patch Sanding Fog seal None reported X X X X X X TABLE 14 CASE STUDIES FOR CHIP SEAL USE ON LOW-VOLUME ROADS
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From page 63... ...
and 3/8 in. Design Method Individual Modified Kearby Empirical Design Done By In-house maintenance engineer In-house design engineer In-house design engineer Design Method Usage Not reported 22 years 5 years Distress Level of Underlying Surface None to moderate Moderate Moderate Structural Condition of Underlying Surface Excellent Good Not reported Computerized Control Required on Distributor/Chip Spreader Yes/No Yes/No Yes/Yes Specified Controls on Rolling Rolling pattern Roller weight and maximum speed Rolling pattern Traffic Control Measures Reduced speed, interim pavement markings, flaggers, pilot cars Reduced speed, interim pavement markings, flaggers, pilot cars Reduced speed, interim pavement markings, flaggers Time to Open to Reduced Speed Traffic 3 h Varies 30 min Aggregate QC Tests % fracture Flakiness Decant Anti-strip Presence of clay Gradation Not reported X X X X X X X X X X Methods to Maintain Seal after construction Crack seal Chip seal patch Lime slurry Fog seal X X X X X X TABLE 15 CASE STUDIES FOR CHIP SEAL USE ON HIGH-VOLUME ROADS
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