Latest pavement topics in Japan

Transcription

1 Latest pavemet topics i Japa Kazuyuki KUBO Leader, Pavemet Team Public Works Research Istitute, Japa

2 Paved Roads i Japa

3 Road ad Pavemet Budget i Japa

4 Drastic chages i the Techical Stadard Before 2001 Maual for Asphalt Pavemet Maual for Cemet Cocrete Pavemet After 2001 Method Specificatio (Structure, Material, Costructio, etc.) Techical Stadard for Pavemet Structure Performace-based Specificatio

5 Differeces betwee Previous Maual ad New Stadard Maual for Asphalt Pavemet Regulated Qualities of materials Desig method - TA method - Desig period = 10 years Costructio Stadard Quality Cotrol Ispectio - Material characteristics - Work quality completed Techical Stadard for Pavemet Structure (2001.6) Showig a performace idex ad a target value (Road admiistrators desigate) Not Regulated Qualities of materials Desig methods - TA method is available - Desig period = free Costructio Stadard Quality Cotrol Oly the check of a performace

6 Method Specificatio TA method Iput data Desig CBR as subgrade stregth Traffic Classificatio as traffic volume Output data TA value

7 Calculatio of TA TA =a1 h1+a2 h2+ +a h ai : coversio coefficiet show i Table-2.9 hi : thickess of each layer (cm) TA TA a1 h1 a2 h2 a h Decided from pavig material s stregth

8 Performace Idexes Obligatory Performace Idexes Durability agaist fatigue crackig - Number of wheel passes causig fatigue failure Durability agaist ruttig - Number of wheel passes causig plastic deformatio Flatess of surface - eveess Optioal Performace Idexes Rai water permeability - Water peetratio amout Skid Resistace Noise reductio Wheel Trackig Test Road Acoustic Checker

9 Number of wheel passes causig fatigue failure - The stadard wheel load is 49 kn. - The properties are to be evaluated by a accelerated i-situ wheel load test or testig o a full-scale specime, or performace of other pavemets which have similar structures. Traffic volume i pavemet plaig (Uit: Large vehicles per day) Number of wheel passes causig fatigue failure (Uit: Cycles over 10 years) 3,000 or more 35,000,000 1,000 or more, but less tha 3,000 7,000, or more, but less tha 1,000 1,000, or more, but less tha ,000 less tha ,000 Ay pavemet structure will be available, whe its structural stregth ca be proved to meet with pla traffic. This proof ca be doe by ot oly theoretically but also empirically. Therefore TA method is still available as a empirical method

10 Advatage of Performace-based Specificatio? Method Specificatio Cotract = Specifyig certai coditios about materials or costructio methods i order for fiished goods to demostrate a target performace Performace-based Specificatio Cotract = Not specifyig materials or costructio methods but specifyig oly target performace of fiished goods Various ew materials ca be applied to pavemet work sites easily Pavemet techologies relatig to evirometal issues have become popular i Japa

11 Draiage Asphalt Pavemets (DAP) i Japa DAP is regarded as oe of the most successful pavemet techology i Japa The umber of traffic accidets decreased sharply after the costructio of DAP More tha 60% of expressways are paved by DAP i Japa Accidet rate (umber of accidets/billio vehicle kilometers) each draiage asphalt pavemet was costructed i this moth Passed moth after draiage asphalt pavemet costructio(moth)

12 Accelerated Loadig Test of DAP DAP was foud to be suddely destroyed i some cases. Ad test pavemet was costructed i Pavemet Test Field to simulate this destructio. After 700 thousads wheels had passed, the ruttig depth had become sharply large, ad this could be estimated to be caused by lateral flow.

13 Lateral Flow Destructio of DAP After its destructio, cut specime was removed to check what has happeed. Heavy lateral flow was foud i both surface ad bider layer at wheel pass. This lateral flow was seemed to be caused by isufficiet adhesio betwee surface ad bider course, aggregate strippig i bider course, ad layer separatio due to stagat water. Isufficiet adhesio betwee surface ad bider courses: Flow is stimulated course Surface course (porous mixture) (Porous asphalt mixture) : Wheel - Wheelpass Lateral flow caused by isufficiet adhesio course (impermeable layer) Bider course (impermeable layer) Strippig caused by water Plastic deformatio of bider course

14 Laboratory Test for Lateral Flow I order to simulate lateral flow, modified immersio wheel trackig test was coducted. Water was sprikled as a artificial raifall. Trackig: 70 wheel passes/mi Surface course (porous asphalt mixture) Draiig Bider course (impermeable layer) Circulatig pump Water spriklig Draiig Air ad water temperatures 60 C Trackig velocity Traverse width Traverse velocity Test duratio Load Wheel width 70 wheel passes/mi. 10 cm 10 cm/mi. Util deformatio reaches 30 mm 1.12 MPa 50 mm

15 Effect of Water Spriklig No.1:With water spriklig No.2:Without water spriklig Water i pavemet is a critical factor to decrease its durability. There could be foud asphalt strippig ad severe deformatio of bider course asphalt cocrete just like the previous cocept. Amout of deformatio (mm) No.1 No Time(mi)

16 Recommedatios for DAP improvemet agaist water The forms of failure of DAP greatly differ depedig o the immersio coditios. The plastic flow resistace of bider course improves the durability of DAP. Higher adhesio betwee surface ad bider courses improves the durability of DAP. I order to obtai higher adhesio, eough amout of rubberized asphalt emulsio or improved asphalt emulsio is ecessary

17 Other Challege for DAP -Two layer DAP- Two layer DAP has bee foud to reduce tire oise about 0.5dB more tha usual DAP MAP(Multi-Layer Asphalt Paver) has bee developed to save costructio cost ad time MAP ca pave two layers simultaeously with differet materials

18 Other Challege for DAP -Fuctio Restoratio Machie- Cleaig machie usig high-pressure water has bee developed to remove dust for the fuctioal restoratio. Recoverig water used for washig Directio of travel Recoverig water used for washig Directio of travel Water tak Tak Tak Ijectio ozzle Ijectio ozzle Cavitatio washig High-vacuum suctio High-pressure water jet Mechaism of high-vacuum performace restoratio vehicle Mechaism of torado-type performace restoratio device

19 Other Pavemet Techologies Cool pavemet Water retetio pavemet Store water iside pavemet Uses the mechaism of latet heat Solar radiatio Latet heat (water evaporatio) Water-retaiig layer Heat shield pavemet Pait special coatig Reflectio of ear-ifrared ray (NIR) Solar radiatio Reflectio of NIR radiatio Thermal barrier coatig

20 Water Retetio Pavemet Porous asphalt cocrete with water retaiig materials i its voids Water retaiig materials Porous silt or sad Water retaiig polymer Near The Capitol

21 Heat-shield Pavemet Thermal barrier coatig o the Pavemet Special Pait Heat reflective pigmet Hollow fie ceramic particles Visible ray =low reflects Near-ifrared ray =high reflects Asphalt Aggregate GINZA Street at Tokyo

22 Simulatio Result Compare with geeral pavemet Maximum surface temperature about -10 Maximum air temperature about -1 (at 1.0m height)

23 Moitored Results (Water Retetio Pavemet) The surface temperature was 16.4 lower tha cotrol sectio. The cool-dow effect lasted for 4-5 days after raifall

24 Future Directio Performace-based specificatio has ehaced developmet of various pavemet techologies Double layer Draiage Asphalt Pavemet Cool Pavemet (Water Retetio Pavemet, Heat Shield Pavemet) Others For better road circumstace ad more cost reductio, Some trials have bee already coducted to assure future performace of pavemet such as, Prescribe rut depth after 3years Prescribe water permeability after costructio ad at oe year later, two year later Water Permeability Test