Transcript Document
Towards Standardizing Construction Specifications and Design Criteria of Agricultural Roads in the GCC Countries Eng. Abdulaziz Al-Kulaib Undersecretary, Ministry of Public Works, Kuwait Eng. Fadel Al-Ajmi Assistant Undersecretary, Maintenance Division, Ministry of Public Works, Kuwait Dr. Sayed Metwali
Advisor,
Maintenance Division, Ministry of Public Works, Kuwait Dr. Ahmad H. Aljassar Associate Professor, Civil Engineering Department, Kuwait University Fourth International Gulf Conference on Roads 10-13 November 2008, Doha, Qatar
Introduction
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ARs to serve farming areas.
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Simplified design because of low traffic volumes.
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One main concern: to minimize cost.
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MPW has been constructing ARs for many years in North and South of Kuwait.
Introduction
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In the past: light traffic consisting of light pickup trucks and occasional heavy trucks.
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Therefore, did not require thick pavements.
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Used to be 50 mm of wearing course on top of 150 mm of prepared subgrade.
Introduction
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Rapid developments of farming areas in recent years resulted in heavier daily traffic (heavy trucks).
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This led to rapid deterioration of pavements.
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Need for stronger pavements was recognized.
Introduction
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In recent years, MPW tendered 6 contracts for construction and maintenance of AR in the Northern and Southern farming areas (total value 12 million KD = 150 million QAR ).
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Cost of AR = 30,000 KD (390,000 QAR) per km.
Cross section
AASHTO recommends 3.6 m Cross slope to facilitate drainage
Typical cross section of an AR
Cross section
Graded and compacted earth shoulders
Cross section
Sunken cast in-situ concrete curb to provide lateral support and protect pavement edge
Road profile
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Follows the natural flat terrain in farming areas.
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Aesthetically pleasing, reduced construction costs, and improved safety.
Road profile
Drainage
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Surface runoff is drained over the crowned pavement, then down the side slopes.
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During winter season, vegetation grows along side slopes. This helps protect them against erosion.
Construction
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Subgrade soil is A-2-4 or better.
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Dry density 1922 kg/m 3 min.
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CBR of 15 min.
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Subgrade thickness is 30 cm min., compated in two layers (each not more than 15 cm).
Construction
Clearing & leveling
Construction
20 cm x 20 cm edge sunken curb
Construction
Subgrade
Construction
Subgrade
Construction
Subgrade
Construction
4 – 5 cm bituminous wearing course 8 – 10 cm bituminous base course
Construction
4 – 5 cm bituminous wearing course 8 – 10 cm bituminous base course
Material properties (aggregates)
Material Type Fine Aggregate Coarse Aggregate Mineral Filler Size Passing # 8 sieve Material Description Natural Sand crushed sand and Main Properties Sand equivalent: 30 min. for crushed sand 45 min. for natural sand soundness loss: 15% max. (AASHTO T-104) Retained on # 8 sieve Crushed natural stone and gravel 100% passing #30 Min. 75% passing #200 Limestone, cement, or hydrated lime Cubic in shape.
Degree of crushing 80% min.
Has at least one fractured face.
Flakiness: 30% max. (BS 812).
Soft and friable particles: 3% max. for base course, 2% max. for binder and surface courses.
Sodium sulfate soundness loss: 12% max.
Abrasion loss: 40% max for surface course, 50% max for base and binder courses (AASHTO T-96).
Free Moisture 30% max.
Lime Index: 50% min.
Unhydrated lime: 9% max.
Carbon Dioxide: 8% max.
Material properties (bituminous mixes)
Sieve
1 1/2" 1" 3/4" 1/2" 3/8" # 4 # 8 # 16 # 30 # 50 # 100 # 200 Bitumen (60/70) % by weight of total aggregate
% passing by weight Base course
100 72 -100 60 - 89 46 – 76 40 - 67 30 - 54 22 – 43 15 – 36 10 – 28 6 – 22 4 – 14 2 – 8 3.5 – 5
Surface course
100 66-95 54 – 88 37 – 70 26 – 52 18 – 40 13 – 30 8 – 23 6 – 16 4 – 10 4.5 – 6.5
Acceptable tolerances
± 5% ± 4 % ± 0.4 % 1600 kg min .
1800 kg min .
Marshall Stability Index of Retained Strength (AASHTO T-165), OR Net Retained Strength 90% min.
14 kg/cm2 min.
Material properties
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Prime coat: - Medium-curing cut back (MC-70).
- Application rate 0.45 – 1.50 kg/m 2 .
- Application temperature 60 o – 80 o - Not allowed if ambient temp. < 13 o C.
C.
Not allowed in presence of surface free water.
Material properties
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Tack coat: - Slow-setting emulsion.
- Application rate 0.15 – 0.75 kg/m 2 .
- Application temperature 10 o – 60 o - Not allowed if ambient temp. < 13 o C.
C.
Conclusion
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ARs are becoming an important element of the highway system.
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They provide farmers with all-weather access to markets.
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Traditional thin pavement design is becoming insufficient to sustain heavier traffic loads on ARs.
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Properties and design features may be of benefit for similar applications in the GCC.
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دمحم هلوسرو هدبع ىلع كرابو ملسو الله ىلصو . .
نيملاعلا بر لله دمحلاو
Copy of this presentation available at www.draljassar.net