Detail of JTG D50-2017

Introduction of JTG D50-2017

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative. As the development of highway construction, improvement of technical level of asphalt pavement, application of new materials and new structures and accumulation of engineering experience, partial content of JTG D50-2006 Specifications for Design of Highway Asphalt Pavement (hereinafter referred to as "the former specification") needs to be revised and perfected. According to the requirements of the document JIAOGONGLUFA [2011] No.115 issued by the Ministry of Transport - Notice on Issuing the Development and Revision Project Plan of Highway Engineering Standards in 2011, CCCC Road and Bridge Consultants Co., Ltd. undertakes the revision work of the former specification. In this specification, the traffic and climate parameters, design parameters, design indexes and relevant performance models in the former specification are revised relying on the domestic and overseas research achievements and engineering practice in recent years and according to the principle of combining inheritance and development. This specification comprises eight chapters and seven annexes, with the main contents covering: design standards, structural composition design, material property requirements and design parameters, checking calculation of pavement structure, renovation design and bridge deck pavement design. The following main changes have been made with respect to the former specification: 1. The investigation and analysis methods of axle load spectrum and traffic parameters are standardized. 2. The temperature adjustment coefficient and equivalent temperature are introduced. 3. Design parameters of pavement materials are changed, and corresponding test and evaluation methods are adjusted. 4. The design indexes for permanent deformation amount of asphalt mixture layer, vertical compressive strain on the top of subgrade and low temperature cracking index of pavement are added, the fatigue cracking prediction model for asphalt mixture layer and inorganic binder stabilized layer is improved, and the design index for pavement surface deflection is cancelled. 5. The arrangement of chapters and sections is sorted to highlight the requirements of structural composition design, and the terms and symbols are standardized. The drafters of this specification are as follows: Chapters 1, 2 and 3: Liu Boying; Chapter 4: Meng Shutao; Chapter 5: Niu Kaimin; Chapter 6 and Annex B: Bai Qifeng; Chapter 7: Cao Rongji; Chapter 8 and Annexes D and E: Wang Lin; Annex A: Zhao Yanqing; Annex C: Yang Xueliang; Annex F: Sun Lijun; Annex G: Tan Zhiming; provisions on pavement deflection analysis: Tang Boming; provisions on pavement low temperature cracking analysis: Feng Decheng; provisions on mechanical parameters of asphalt binder materials and fatigue analysis of asphalt mixture layer: Yu Jiangmiao; Zhao Duijia participates in preparation of partial provisions in Chapter 5 and Tai Diancang participates in the preparation of partial provisions in Annex C. During the process of implementing this specification, all parties concerned are kindly requested to send the problems found and opinions by correspondence to the routine management group of this specification (contact person: Liu Boying; address: Beijing Jiangsu Plaza, No.D88, Andingmenwai Street, Dongcheng District, Beijing, 100011, China; Tel: 010-82016573; Fax: 010-82016573; email: goodpave@163.com; website: www.goodpave.com; WeChat Official Account: goodpave) for reference in the next revision. Contents 1 General Provisions 1 2 Terms and Symbols 2 2.1 Terms 2 2.2 Symblos 3 3 Design Standards 4 4 Structural Composition Design 7 4.1 General Requirements 7 4.2 Pavement Structure Composition 7 4.3 Subgrade 8 4.4 Base and Subbase 8 4.5 Surface Course 10 4.6 Functional Layers 11 4.7 Shoulder 12 4.8 Pavement Drainage 12 5 Material Property Requirements and Design Parameters 14 5.1 General Requirements 14 5.2 Subgrade 14 5.3 Granular Materials 14 5.4 Inorganic Binder Stabilized Materials 16 5.5 Asphalt Binder Materials 18 5.6 Poisson's Ratio 24 6 Checking Calculation of Pavement Structure 25 6.1 General Requirements 25 6.2 Design Indexes 25 6.3 Traffic, Material and Environment Parameters 26 6.4 Checking Calculation Process of Pavement Structure 27 7 Renovation Design 30 7.1 General Requirements 30 7.2 Investigation and Analysis of Existing Pavement 30 7.3 Renovation Scheme 31 7.4 Checking Calculation for Renovated Pavement Structure 32 8 Bridge Deck Pavement Design 37 8.1 General Requirements 37 8.2 Cement Concrete Bridge Deck Pavement 37 8.3 Steel Bridge Deck Pavement 38 Annex A Analysis of Traffic Load Parameters 39 Annex B Method of Checking Calculation of Pavement Structure 47 Annex C Asphalt Pavement Structure Scheme 60 Annex D Test Method of Rebound Modulus of Granular Material 62 Annex E Test Method for Uniaxial Compression Modulus of Inorganic Binder Stabilized Materials 69 Annex F Uniaxial Penetration Strength Test Method of Asphalt Mixture 74 Annex G Temperature Adjustment Coefficient and Equivalent Temperature 79 Explanation of Wording in This Specification 87 1 General Provisions 1.0.1 This specification is formulated with view to being adapt to the needs of highway industry development and highway construction, improving the design quality and service performance of asphalt pavement and ensuring the safety, reliability and economic rationality of engineering. 1.0.2 This specification is applicable to the asphalt pavement design in highway construction and renovation engineering of all classes. 1.0.3 Structural composition design, material design and thickness design shall be carried out according to the highway class, pavement service performance requirements and the traffic load required to be borne and in combination with local climatic, hydrological, geological, material, construction and curing conditions, the engineering practice experience, environmental protection requirements, etc., and then the design scheme shall be selected through techno-economic analysis. 1.0.4 The subgrade shall meet the minimum rebound modulus requirement, and appropriate dry and wet types shall be available. Comprehensive design of subgrade and pavement shall be carried out on the basis of investigating and mastering the soil quality and dry/wet type of subgrade along the line. 1.0.5 New technology, structure, material and process shall be selected positively and reliably in combination with local conditions and engineering experience. 1.0.6 In addition to complying with the relevant requirements of this specification, the pavement design in such special areas as desert, expansive soil and saline soil shall also take regional particularity into consideration and include corresponding technical measures in combination with local experience and achievements. 1.0.7 In addition to those specified in this specification, the design of asphalt pavement shall also meet the requirements of current relevant national and professional standards.   2 Terms and Symbols 2.1 Terms 2.1.1 asphalt pavement pavement with asphalt surface course 2.1.2 reliability probability of pavement structure completing intended function within the specified period and under the specified conditions. The reliability that the design structure is required to reach is called target reliability 2.1.3 reliability index value index used for measuring the reliability of pavement structure. The reliability index used as the design basis of pavement structure according to this specification is called target reliability index 2.1.4 design working/service life of pavement intended working/service life of pavement free from structural repair under normal design, construction, service and maintenance conditions 2.1.5 design axle load calculated axle load adopted in design of pavement structure 2.1.6 equivalent single axle loads design equivalent single axle loads converted from different single axle loads according to equivalent damage principle 2.1.7 cumulative equivalent single axle loads sum of equivalent single axle loads on design lane within the design working/service life 2.1.8 seal coat functional layer used for preventing water from infiltrating in pavement structure 2.1.9 tack coat functional layer playing the role of binding in pavement structure 2.1.10 prime coat functional layer applied on nonasphaltic material layer and being capable of penetrating into certain depth in the surface to enhance the integrity of nonasphaltic material layer and asphalt mixture layer 2.1.11 drainage layer functional layer used for discharging internal water of pavement structure 2.1.12 frost protection layer functional layer paved in pavement structure according to frost protection requirements 2.1.13 subgrade equilibrium moisture subgrade moisture in a stable equilibrium state with the surrounding environment 2.1.14 low temperature cracking index index representing the low temperature shrinkage cracking degree of asphalt surface course 2.2 Symblos CI——the low temperature cracking index; E——the modulus; G*——the complex dynamic shear modulus of asphalt; h——the thickness; l——the deflection value; N——the single axle loads; P——the axle load; R——the strength; Ra——the permanent deformation amount of asphalt mixture layer; St——the stiffness modulus of asphalt; s——the standard deviation; T——the temperature; ε——the strain; σ——the stress; β——the target reliability index.   3 Design Standards 3.0.1 The target reliability and target reliability index of pavement structure shall not be less than those specified in Table 3.0.1. Table 3.0.1 Target Reliability and Target Reliability Index Highway class Expressway Class I highway Class II highway Class III highway Class IV highway Target reliability (%) 95 90 85 80 70 Target reliability index β 1.65 1.28 1.04 0.84 0.52 3.0.2 The design working/service life of constructed asphalt pavement structure shall not be less than those specified in Table 3.0.2 and shall be comprehensively determined according to factors such as highway class, economy and traffic load class. For the design of renovated pavement, appropriate design working/service life may be selected according to the actual engineering conditions. Table 3.0.2 Design Working/Service Life of Pavement Structure (Years) Highway class Design working/ service life Highway class Design working/ service life Expressway and Class I highway 15 Class III highway 10 Class II highway 12 Class IV highway 8 3.0.3 In pavement design, the single-axle-dual-wheel-set axle load with axle weight of 100kN shall be adopted as the design axle load, and the calculation parameters shall be determined according to Table 3.0.3. The cumulative equivalent single axle loads shall be determined according to Annex A herein based on the design working/service life of pavement structure. Table 3.0.3 Parameters of Design Axle Load Design axle load (kN) Tyre ground pressure (MPa) Diameter of equivalent single-wheel ground circle (mm) Center distance of two wheels (mm) 100 0.70 213.0 319.5 3.0.4 The traffic load borne by pavement structure shall be classified according to Table 3.0.4. Table 3.0.4 The Design Traffic Load Class Design traffic load class Extremely heavy Extra heavy Heavy Medium Light Accumulative traffic volume of large passenger cars and trucks on design lane within the design working/service life (×106, vehicles) ≥50.0 50.0~19.0 19.0~8.0 8.0~4.0 <4.0 Note: Large passenger car and truck are Categories 2~11 vehicles listed in Table A.1.2 in Annex A. 3.0.5 In the design of asphalt pavement, the fatigue cracking damage of asphalt mixture layer, fatigue cracking damage of inorganic binder stabilized layer, permanent deformation amount of asphalt mixture layer, vertical compressive strain on the top of subgrade, and low temperature cracking of pavement in seasonally frozen ground area shall be well controlled. 3.0.6 The design index for service performance of pavement shall meet the following requirements: 1 The fatigue cracking life of both asphalt mixture layer and inorganic binder stabilized layer calculated according to B.1 and B.2 in Annex B shall not be less than the cumulative equivalent single axle loads within design working/service life determined according to Annex A. 2 The permanent deformation amount of asphalt mixture layer calculated according to B.3 of Annex B shall not be larger than the permissible permanent deformation amount listed in Table 3.0.6-1. Table 3.0.6-1 Permissible Permanent Deformation Amount of Asphalt Mixture Layer (mm) Base type Permissible permanent deformation amount of asphalt mixture layer Expressway and Class I highway Classes II and III highways Inorganic binder stabilized base, cement concrete base, and asphalt mixture base with inorganic binder stabilized subbase 15 20 Other bases 10 15 3 The vertical compressive strain on the top of subgrade shall not be larger than the permissible value calculated according to B.4 in Annex B. 4 The low temperature cracking index of asphalt surface course in seasonally frozen ground area calculated according to B.5 in Annex B should not be larger than the value listed in Table 3.0.6-2. Table 3.0.6-2 Requirements for Low Temperature Cracking Index Highway class Expressway and Class I highway Class II highway Classes III and IV highways Low temperature cracking index CI, ≤ 3 5 7 Note: The low temperature cracking index CI - during completion acceptance, as for the number of transverse cracks in a 100m survey unit, the crack running through the full width is counted as 1 crack, the one not running through the length but exceeding the width of one lane is counted as 0.5 crack and the one not exceeding the width of one lane is excluded. 3.0.7 During handover acceptance of expressway and Class I highway as well as the Classes II and II highways in heavy-hilly area, the technical index of their anti-sliding performance shall meet the technical requirements specified in Table 3.0.7. Table 3.0.7 Technical Requirements for Anti-sliding Performance Mean annual precipitation (mm) Handover test index value Sideway force coefficient, SFC60a Texture depth, TDb (mm) >1,000 ≥54 ≥0.55 500~1,000 ≥50 ≥0.50 250~500 ≥45 ≥0.45 Notes: a The sideway force coefficient SFC60 - it is determined with sideway force coefficient test vehicle in a speed of 60km/h±1km/h. b The texture depth TD - it is determined with sand patch method.   4 Structural Composition Design 4.1 General Requirements 4.1.1 The pavement structure composition design shall be carried out in allusion to the mechanical properties, functional characteristics, long-term performance decay rules and damage characteristics of various pavement structure compositions, follow the concept of comprehensive design of subgrade and pavement and ensure the safety, durability, and economic rationality in entire life cycle of the pavement structure. 4.1.2 The pavement structure may consist of surface course, base, subbase and necessary functional layers. The surface course may be paved in layers with different materials and may be divided into upper surface course, middle surface course and lower surface course. 4.1.3 Within the design working/service life, the pavement shall be free from any structural damage due to fatigue, and the surface course may be subject to surface function recovery. 4.1.4 Tack coat shall be applied between asphalt binder material layers; seal coat shall be applied between asphalt binder material layer and other material layer, and prime coat should also be applied. 4.11.5 Waterproofing and drainage measures shall be taken for pavement structure to prevent rainfall from infiltrating into the pavement structural layer. 4.2 Pavement Structure Composition 4.2.1 The pavement structure type shall be selected according to factors such as traffic load class and subgrade condition and in combination with the material and structural characteristics of pavement. 4.2.2 The pavement structure may be classified into four types, i.e., asphalt pavement with inorganic binder stabilized base, asphalt pavement with granular base, asphalt pavement with asphalt binder base and asphalt pavement with cement concrete base. 4.2.3 The selection of pavement structure should meet the following requirements: 1 Asphalt pavement with inorganic binder stabilized base is applicable to various traffic load classes. 2 Asphalt pavement with granular base is applicable to "Heavy" or below traffic load classes. 3 Asphalt pavement with asphalt binder base is applicable to various traffic load classes. 4 Asphalt pavement with cement concrete base is applicable to "Heavy" or above traffic load classes. 4.2.4 When the subgrade moisture state is medium wet or wet, granular subbase should be adopted or granular subgrade improvement layer should be applied. 4.2.5 In rainy areas, appropriate measures shall be taken for asphalt pavement with inorganic binder stabilized base and that with cement concrete base to control such water damages as pumping and cavity. 4.2.6 For inorganic binder stabilized base, the following one or several measures may be taken to reduce shrinkage crack of base and reflection crack of pavement: 1 Inorganic binder stabilized base with good crack resistance is selected. 2 The thickness of asphalt mixture layer is increased, or asphalt macadam layer or graded crushed stone layer is applied on inorganic binder stabilized base. 3 Modified asphalt stress-absorbing layer is applied or geosynthetic is paved on inorganic binder stabilized base. 4.2.7 With the structural composition selected, the thickness of each structural layer may be primarily selected according to traffic load class and by reference to Annex C herein. 4.3 Subgrade 4.3.1 Subgrade shall be stable, dense and uniform, and be with adequate bearing capacity. 4.3.2 For the road section with soil cutting or heavily weathered rock in rainy areas, the drainage design of the junctions between filling and excavation and the cutting sections shall be strengthened to improve the hydrological condition of subgrade. 4.3.3 Leveling layer shall be arranged on the top of rock subgrade or rockfill subgrade, of which the thickness should be 200~300mm. 4.3.4 The constructed highway roadbed shall be in dry or medium wet state and shall be provided with measures to avoid ingress of surface water or groundwater. 4.4 Base and Subbase 4.4.1 Base and subbase shall have adequate bearing capacity, anti-fatigue-cracking performance, adequate durability and water stability. The asphalt binder base and granular base also shall have adequate resistance to permanent deformation. 4.4.2 The material type of base and subbase may be selected by reference to Table 4.4.2. Table 4.4.2 Applicable Traffic Load Class and Layer Position of Base and Subbase Materials Type Material type Applicable traffic load class and layer position Inorganic binder stabilized type Cement stabilized graded crushed stone or gravel, cement and fly ash stabilized graded crushed stone or gravel, and lime and fly ash stabilized graded crushed stone or gravel Base and subbase of each traffic load class Cement stabilized unscreened crushed stone or gravel, lime and fly ash stabilized unscreened crushed stone or gravel, and lime stabilized unscreened crushed stone or gravel Base of "Light" traffic load class, and subbase of each traffic load class Cement stabilized soil, lime stabilized soil and lime and fly ash stabilized soil Base of "Light" traffic load class, and subbase of each traffic load class Granular type Graded crushed stone Base of "Heavy" or below traffic load classes, and subbase of each traffic load class Graded gravel, unscreened crushed stone, natural sand gravel and caulking crushed stone Base of "Medium" and "Light" traffic load classes, and subbase of each traffic load class Asphalt binder type Dense-graded asphalt macadam, half-open-graded asphalt macadam and open-graded asphalt macadam Base of "Extremely Heavy", "Extra Heavy" and "Heavy" traffic load classes Bituminous penetration macadam Base of "Heavy" or below traffic load classes Cement concrete type Cement concrete or lean concrete Base of "Extremely Heavy" and "Extra Heavy" traffic load classes 4.4.3 Recycled asphalt mixture and recycled inorganic binder stabilized material may be used for base and subbase of each traffic load class; plant-mixed hot-recycled asphalt mixture should be adopted for the base of "Extremely Heavy", "Extra Heavy" and "Heavy" traffic load classes. 4.4.4 Graded crushed stone layer or semi-open-graded or open-graded asphalt macadam layer may be applied between inorganic binder stabilized layer and asphalt binder material layer. 4.4.5 The thickness of base and subbase of different materials should meet those specified in Table 4.4.5. Table 4.4.5 Thickness of Base and Subbase Material type Nominal maximum particle size of aggregate (mm) Thickness (mm), ≥ Dense-graded asphalt macadam Half-open-graded asphalt macadam Open-graded asphalt macadam 19.0 50 26.5 80 31.5 100 37.5 120 Bituminous penetration macadam - 40 Lean concrete 31.5 120 Inorganic binder stabilized material 19.0, 26.5, 31.5, 37.5 150 53.0 180 Graded crushed stone Graded gravel Unscreened crushed stone and natural sand gravel 26.5, 31.5, 37.5 100 53.0 120 Caulking crushed stone 37.5 75 53.0 100 63.0 120 4.4.6 Cement concrete base of asphalt pavement shall meet the relevant requirements of current JTG D40 Specifications for Design of Highway Cement Concrete Pavement. 4.5 Surface Course 4.5.1 The surface course shall be event and resistant to rutting, fatigue cracking, low temperature cracking and water damage, the upper surface course mixture shall also be resistant to sliding and abrasion, and the dense graded asphalt mixture upper surface course shall be with low permeability. 4.5.2 The material type of surface course should be selected according to Table 4.5.2.

Contents of JTG D50-2017

1 General Provisions 2 Terms and Symbols 2.1 Terms 2.2 Symblos 3 Design Standards 4 Structural Composition Design 4.1 General Requirements 4.2 Pavement Structure Composition 4.3 Subgrade 4.4 Base and Subbase 4.5 Surface Course 4.6 Functional Layers 4.7 Shoulder 4.8 Pavement Drainage 5 Material Property Requirements and Design Parameters 5.1 General Requirements 5.2 Subgrade 5.3 Granular Materials 5.4 Inorganic Binder Stabilized Materials 5.5 Asphalt Binder Materials 5.6 Poisson's Ratio 6 Checking Calculation of Pavement Structure 6.1 General Requirements 6.2 Design Indexes 6.3 Traffic, Material and Environment Parameters 6.4 Checking Calculation Process of Pavement Structure 7 Renovation Design 7.1 General Requirements 7.2 Investigation and Analysis of Existing Pavement 7.3 Renovation Scheme 7.4 Checking Calculation for Renovated Pavement Structure 8 Bridge Deck Pavement Design 8.1 General Requirements 8.2 Cement Concrete Bridge Deck Pavement 8.3 Steel Bridge Deck Pavement Annex A Analysis of Traffic Load Parameters Annex B Method of Checking Calculation of Pavement Structure Annex C Asphalt Pavement Structure Scheme Annex D Test Method of Rebound Modulus of Granular Material Annex E Test Method for Uniaxial Compression Modulus of Inorganic Binder Stabilized Materials Annex F Uniaxial Penetration Strength Test Method of Asphalt Mixture Annex G Temperature Adjustment Coefficient and Equivalent Temperature Explanation of Wording in This Specification