EXAMINATION OF AIRPORT RUNWAY REPAIRED USING COARSE-GRADED WARM-MIX ASPHALT MIXTURE 大粒径中温化アスコンを使用した滑走路補修に関する検討 Civil Engineering Research Institute of Hokkaido Ryuji ABE Hideto TAKEMOTO Hokkaido Regional Development Bureau Toshifumi HIRAO Background 背景 A runway inspection in June 2000 detected a number of circular blisters on the runway pavement An extensive core sampling of the entire runway found delamination of asphalt concrete layers and severe spalling of the asphalt stabilization course from asphalt-aggregate debonding in several places. 平成１２年６月の滑走路点検時にＡ滑走路に舗装表面が円形状に膨れ 上がるブリスタリング現象が多数発見された。 全滑走路延長にわたり、コア採取調査を実施。層間剥離や舗装体が破 損している箇所が確認され、飛行機の安全走行上、早急に対策を行う必 要がある。 Survey purpose 調査目的 To examine causes of blistering and pavement deterioration at New Chitose Airport Requirements for and methods of improvement work 新千歳空港の舗装体の劣化原因の解明 対策工法の検討 Plan view of New Chitose Airport 新千歳空港平面図 L=3000m Runway B Runway B Runway A Runway A Parallel Taxiway D Parallel Taxiway D P=4700 Items surveyed 調査項目（現地調査） Item 調査項目 Survey purpose 調査目的 Survey on damage to sample cores Investigation of the section and range of pavement failure 採取コアの破壊状況調査 Survey on water content in sample cores 採取コアの水分量調査 Pressurized permeability test 加圧式等水量試験 Asphalt property test アスファルトの性状試験 Marshall stability test マーシャル安定度試験 Immersion Marshall stability 水浸マーシャル安定度試験 舗装体の破損箇所、破損範囲の把握 Investigation of water content and void content in pavement 舗装体に含まれる水分量の把握および舗装体の空隙率の把握 Investigation of water-tightness of pavement 舗装体の水密性の把握 Investigation of asphalt failure アスファルトの劣化状況の把握 Investigation of pavement strength 舗装体の強度の把握 Calculation of pavement equivalents 舗装体の等値換算値の算出 Maximum pavement surface temperature of New Chitose Airport 新千歳空港の路面最高路面温度 Maximum pavement surface temperature Month 51～55℃ 56～60℃ 0 0 0 0 0 0 ～50℃ April Frequency Said day Day May Frequency 6 Said day Day 17,18,19,24,25,30 June Frequency 4 4 Said day Day 13,24,29,30 16,17,18,21 July Frequency 5 3 1 Said day Day 6,7,16,24,25 2,11,14 10 August Frequency 7 2 1 Said day Day 8,9,12,13,14,19,21 18,24 17 Total Frequency 22 9 2 Waterless core (P=4700) 無水コアの状況（P=4700） Survey section No. 3Runway AObservation point SP=4700 Layer thickness Douroscope Formation コア内部状況 構成 層厚(m) Overlay オーバーレイ Dense-graded asphalt mixture 0.058 0.06 0.047 旧表層 Coarse-graded asphalt mixture 基層 10m from CL on the R side Depth Sample core 採取コア 深度(m) 0.11 0.050 0.16 0.065 0.22 Asphalt stabilization ｱｽﾌｧﾙﾄ安定処理 0.095 0.32 Asphalt stabilization ｱｽﾌｧﾙﾄ安定処理 0.093 0.41 Damage to each runway layer (right side of Runway A) 5 1st layer 2nd layer 4 3rd layer 3 4th layer 5th layer 2 6th layer 1 Total 6th 4800 4600 4400 4200 4000 3800 3600 3400 3200 Observation point 3000 2800 2600 2400 2200 2000 1800 0 Nunber of collapses and cracks 6 各層の破損状況（R側） 1st laye r laye r Water content in Runway A (P = 4700) Ａ滑走路の含水比(P=4700) Construction joints Construction joints 2.5 Upper binder course (coarse-graded asphalt mixture) Lower binder course (coarse-graded asphalt mixture) 2 Water content(%) Construction joints 1.5 1 0.5 0 0 5 10 15 20 Distance from center (m) 25 30 Void content in Runway A (P=4700) A滑走路の空隙率(P=4700) Void content (%) Construction joints 10.00 Construction joints Construction joints 9.00 8.00 7.00 6.00 5.00 4.00 3.00 2.00 1.00 0.00 Overlay layer Surface course 0 5 10 15 20 Distance from center 25 30 Pressurized permeability test 加圧透水試験 Observation point Name of mixture P=3200 P=3400 P=4000 P=4100 1.43×10-5 Impermeable water 4.43×10-4 Impermeable Impermeable water water 1.66×10-4 1st layer Overlay オーバーレイ層 Impermeable water 2nd layer Dense-graded asphalt mixture 旧表層 1.74×10-7 3rd layer Coarse-graded asphalt mixture 基層（上部） 6.89×10-4 th 4 layer Coarse-graded asphalt mixture Impermeable 基層（下部） water 4.88×10-4 1.70×10 -3 1.52×10-5 4.12×10 -5 5.10×10-5 1.79×10 -4 5th layer Asphalt stabilization アスファルト安定処理（上部） 9.13×10-4 9.55×10-4 Impermeable water 4.33×10-4 6th layer Asphalt stabilization アスファルト安定処理（下部） 1.06×10-3 3.36×10-3 4.34×10-4 2.04×10-3 Unit:cm/sec Pavement damages and their causes 損傷原因の推定図 Requirements for and methods of improvement work 改良工法の検討 Requirement and Improvement method: The repair work of Runway A should be was carried out under normal operation of the runway. Hours of repair work should be from 23:00 to 6:00 the next morning, i.e., when the runway is closed. The thick-lift method was employed for asphalt placement after the removal of the existing asphalt stabilization course, which had severe spalling. The method facilitates a thicker placement thickness of asphalt per spreading than conventional methods and thus reduces the time required for installation. To enable rapid re-trafficking, warm-mix asphalt mixture that can be placed at temperatures 30 to 50℃ lower than hot-mix asphalt mixture was employed 運用・工法に関する条件 ①Ａ滑走路は工事期間中、空港閉鎖は行わない。 ②施工時間は23:00～6:00まで ③砂利状化している既設安定処理層撤去後の復旧は、施工時間短縮からシックリフト工法 （大粒径アスファルト混合物）を検討 ④交通開放までの冷却時間の短縮から30～50℃温度低下が可能な中温化混合物の検討 Pavement recovery process at New Chitose Airport 新千歳空港の作業工程 st 1 stage 60.0ｍ 20.0 10.0 10.0 20.0 第一工程 Zonal cutting (t=42cm) 帯状切削 L10 Ｃ Ｌ R10 3.8 6.2 3.8 6.2 3.8 60.0ｍ 20.0 10.0 10.0 20.0 Temporary surface course (t=16cm) 上層路盤 L10 Ｃ Ｌ R10 3.8 6.2 3.8 6.2 3.8 20.0 60.0ｍ 10.0 10.0 20.0 Base course (t=26cm) 暫定表層 L10 Ｃ Ｌ R10 3.8 6.2 3.8 6.2 3.8 Test pavements 試験施工 大粒径中温化アスファルト混合物の適用性の検討 Items surveyed in the test construction Items surveyed 調査項目 Survey purpose 調査目的 Combination of construction machines/ Selection of construction machines/Investigation frequency of rolling compaction of core density at the site 施工機械の組み合わせ・転圧回数 転圧機械の構成、現場密度の把握 Measurement of mixture temperature 混合物の温度測定 Investigation of decrease in temperature of coarse-graded warm mixed asphalt mixture Evenness test Investigation of evenness 平坦性試験 平坦性の把握 Driving test Investigation of initial rutting 走行試験 初期わだちの把握 Stationary steering test Investigation of stationary steering resistance すえ切り試験 すえ切り抵抗の把握 中温化混合物の温度低下状況の把握 Measurement of texture depth using the Measurement of pavement surface texture depth sand patching method 舗装路面のきめ深さの把握 サンドパッチング法によるきめ深さ測定 Vehicle-traveling test 走行試験 Conclusion Causes of pavement deterioration まとめ 1) Water intruding from structurally weakened construction joints was trapped in the pavement body and between layers. 2) Watertight mixture was applied to pavement as overlay, producing impermeable sections. 3) Water trapped between layers and under construction joints evaporated from solar heat as the atmospheric temperature rose, which generated vapor that blistered the pavement body. 4) An asphalt stabilization course with high void content and water-holding capacity retained water. Asphalt deterioration induced by water erosion and freeze-thaw resulted in aggregateasphalt debonding. ブリスタリング現象の発生原因 ①舗装構造上の弱点である施工継目から浸透した水が舗装体に滞水し、舗装体や層間に水分が含 まれるようになった。 ②オーバーレイ工事により水密性の高い混合物が舗設され、不透水になった箇所が生じた。 ③外気温が高い時期に層間や施工継目に含まれた水分が日射により気化し、蒸気となって舗装体 を持ち上げるブリスタリング現象が生じた。 ④空隙率が高く保水能力の高いアスファルト安定処理層に滞水し、水による劣化や凍結融解によっ てアスファルトが劣化し、骨材が剥離する状態になった。 Conclusion まとめ Test construction result Through the application of coarse-graded warm-mix asphalt mixture to 42-cm-thick pavement, it was verified that lowtemperature installation and proper temperature control of mixture achieves the required durability/stability, as seen in the flow resistance and resistance to aggregate-asphalt debonding on the surface. 試験施工の結果 舗装厚42cmの大粒径混合物は充分な温度管理を行うことに より、耐流動性や骨材飛散抵抗などの早期供用性に必要な 耐久性を確保することが可能である。 Postscript おわりに Follow-up research will be organized to investigate the mechanism of pavement deterioration and to examine the applicability of remedial measures. 損傷原因のメカニズムや対策工法の有効性の検証
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