3rd International Road Surface Friction Conference Laboratory Simulation Test Method for Skid Resistance Performance of Chip Seals 111111111111 By Yuhua Li, Yuying Liu Associate Professor Dalian University of Technology Dalian City, China

Outline ◎ Background ◎ Indoor Specimen Molding Methods ◎ Quality Evaluation Test Methods of the Molded Specimen ◎ Skid Resistance Test ◎ Discussion ◎ Conclusions

Backgrounds Chip Seal (also called “Seal Coat”, “Sprayed Seal ”, “Surface Treatment” , etc. ) ◎ Protects underlying pavement ◎ Waterproofs the pavement surface ◎ Improves surface friction (safety) ◎ Extends pavement service life ◎ Costs effective surface treatment

Backgrounds ◎ Chip seal has been widely used in Australia, New Zealand, America, South-Africa , England and so on. (It has a history of more than 75 years) ◎ Technology regulations or manual on design, construction and quality control have been formed. ◎ In China, the traditional chip seal is called “surface dressing and seal”. ◎ There has no special regulations or manual on chip seal in China. Australia America

Backgrounds ◎ In 2007, Liaoning province imported a device of fiber seal coat - SECMAIR. ◎ It is used for wearing course of asphalt pavement in Shenyang, Dalian, Jinzhou city , etc. ◎ Research project, Experiment Study of Fiber Seal Coat , was completed in 2010, by DLUT. ( I am the project leader) Lack of standard test methods, especially the method of molding specimen. ◎ Field and indoor testing methods ( the main problems to be solved )

Backgrounds The Key Difficulties …… How to mold the specimen How to get the specimen How to mold the specimen Multi-layer structure (Non-uniform mixture) Early stage – During Construction Thin! Thin layer of mixture structure (Poor uniform mixture) Main Features Key Difficulties Post phase – After Opening Traffic (about 1~3 months) ◎ Thin layer : H=5~15mm ◎ Non-uniform mixture

Construction Simulation Backgrounds General Approach Field - Laboratory Test (High cost, Inflexible) (The actual project, Liaoning Province, China ) (Literature: by Jaejun Lee, North Carolina) (Using MMLS3 device) Construction Simulation - Laboratory Test Approach Adopted (Low cost, Good flexibility) Construction Simulation Indoor Specimen Laboratory Test

Quality Evaluation Test Methods Key Topics Indoor Specimen Molding Methods Quality Evaluation Test Methods of the Molded Specimen Skid Resistant Test in Laboratory

Indoor Specimen Molding Methods Construction procedures Original pavement surface disease treatment Spraying emulsion (+ fiber) Spreading aggregate Initial rolling Early main-tenance Long-term natural traffic rolling Plate specimens made (Underlay plate ) Spraying emulsion (+ fiber) Spreading aggregate Initial rolling Early curing Post-rolling Step-1 Step-2 Step-3 Step-4 Step-5 Step-6 Indoor simulation

Indoor Specimen Molding Methods Step-1: Underlayer Plate Specimens Made Mould A plate specimen of asphalt mixture is used as under layer after long-term aging treatment. 300mm×300mm×50mm ◎ Simulate the original asphalt pavement structure AC-16 Mix Surface hardness is the most important properties of pavement structure. Embedment 300mm×300mm×40mm ◎ Simulate technology condition of the original pavement Pavement surface diseases will be taken into consideration such as cracks, surface roughness, etc. Cracks Cracks Pavement Surface Plate Specimen

Indoor Specimen Molding Methods Step-2: Spraying emulsion / asphalt / (+fiber) By manual brushing or by mechanical spraying Step-3: Spreading aggregate Uniformity and Accuracy! By manual or mechanical

Indoor Specimen Molding Methods Step-4: Initial Rolling In chip seal construction, a roller is employed to embed the aggregates into the emulsion film and to ensure an initial bond with the binder film without crushing the aggregate. Roller width = 50mm ◎ Roller Types Pneumatic tire roller or Rubber-coated steel drum roller Roller width = 200mm Roller width = 200mm Rolling equipment specially crafted a) Rubber-coated roller

Indoor Specimen Molding Methods rubber cushion thick (10mm, 15mm) b) Steel roller with a underlay rubber cushion ◎ Temperature of initial rolling (a) from 40°C ~ 70°C or (b) at room temperature 15°C ~ 25°C ◎ Time of initial rolling (a) 1min or (b) 3~5 times

Indoor Specimen Molding Methods Step-5: Initial Maintenance ◎ Temperature of initial maintenance 40°C ~ 60°C ◎ Time of initial maintenance in 4 hours Oven Step-6: Post-rolling and post-stage maintenance In order to simulate the long-term compaction process of natural vehicle after opening to traffic. ◎ Time of post-rolling 30min, interval of 6 hours ◎ Temperature of post-stage maintenance 60°C ~40°C OK Molded specimens

Indoor Specimen Molding Methods Molded Specimens By Yuhua Li and Yuxing Liu, DLUT, China, 2009-07

Indoor Specimen Molding Methods Molded Specimens By Yuhua Li and Yuxing Liu, DLUT, China, 2009-07

Quality Evaluation Test Methods Key Topics Indoor Specimen Molding Methods Quality Evaluation Test Methods of the Molded Specimen Skid Resistant Test in Laboratory

As comparison , the testing results are assumed to be the true value. Quality Evaluation Test Methods of the Molded Specimen ◎ Field Testing As comparison , the testing results are assumed to be the true value. ⊙ Pull out test No. 312 Highway in Liaoning Province, 2009-07

Quality Evaluation Test Methods of the Molded Specimen ◎ Field Testing ⊙ Texture depth test No.312 Highway in Liaoning Province, China, 2009-07

Quality Evaluation Test Methods of the Molded Specimen ◎ Indoor Testing ⊙ Pullout test By Li kun, DLUT, China, 2009-08

Quality Evaluation Test Methods of the Molded Specimen ◎ Indoor Testing ⊙ Wet Track Abrasion Loss By Ye jian, DLUT, 2009-08

Quality Evaluation Test Methods Key Topics Indoor Specimen Molding Methods Quality Evaluation Test Methods of the Molded Specimen Skid Resistant Test in Laboratory

⊙ Pendulum Coefficient of Friction Test (BPN) Skid Resistance Test ◎ Testing Method ⊙ Texture Depth Test ⊙ Pendulum Coefficient of Friction Test (BPN)

Discussion ◎ Field texture depth test results ⊙ The TD would decrease greatly in the first 2~3 days after opening to traffic, no matter where the testing sites are, after 7 days the speed reduces. ⊙ When the time is 2-3 months(80days), the speed is going steady.

Discussion ◎ Indoor texture depth test results ⊙ Indoor TD test results agree with field TD test results. The value decreases with increasing rolling time, and be more stable after 4 days. ⊙ The smaller values are obtained in high curing temperature conditions.

Discussion ◎ Indoor skid resistance test result (BPN) ⊙ The results indicate that friction coefficient also decreases with increasing rolling time, and be more stable after 3 days. ⊙ The smaller values of friction coefficient are obtained in high curing temperature conditions.

Conclusions ◎ The chip seal test specimens can be molded by the simulation method, which taking the original pavement structure and the pavement distresses into consideration, and according to the construction process. ◎ The molded specimens indoor can be used to complete Pullout Test, Texture Depth Test, Wet Track Abrasion Loss Test, BPN Test, etc. ◎ The indoor TD test result shows the same trend in compare with the field test result. It is believed that, the indoor BPN test result can approximately predict the chip seal pavement skid resistance.

Thank you for your attention.

Seal coat is an asphaltic coating, with aggregate, applied to the surface of a pavement structure for the purpose of waterproofing and preserving the surface, reconditioning a previous asphaltic surface treatment, improving the surface texture of the wearing surface, changing the surface color or providing resistance to traffic abrasion. A Chip Seal is generally defined as a surface treatment in which the pavement is sprayed with asphalt (generally emulsified) and then immediately covered with aggregate and rolled.