1.0.1 This code is prepared with a view to standardizing the durability design on concrete structure of railway and ensuring concrete structure of railway meets the operating requirements within the design working life.
1.0.2 This code is applicable to the durability design on concrete structure of railway with normal concrete under actions of common environments, such as carbonized environment, chloride environment, chemical erosion environment, sulfate physical attack environment, freezing-thawing environment and abrasion environment. The durability design on concrete structure of railway under the action of other special environments shall be subjected to special research and demonstration in advance.
1.0.3 The durability design requirements specified in this code are the basic requirements to ensure railway concrete structure to reach the design working life. If necessary, they may be raised properly according to the actual engineering conditions and specific environmental conditions.
1.0.4 The durability design on concrete structure of railway shall comply with the following principles:
1 The durability design shall be premised on sufficient load bearing capacity and good cracking resistance of the structure.
2 The durability design shall be carried out according to the design working life, environment type and action grade of the structure.
3 The durability design shall reasonably arrange the structure construction from the perspective of being convenient for construction and avoiding adverse effect of the environment to the structure.
4 The durability design shall propose reliable enhanced protective measures for the concrete structure under severely corrosive environment.
5 The durability design shall make a plan for inspection and maintenance of the structure within design working life in advance and define the follow-up inspection contents.
6 The durability design shall take full consideration of the influence of shrinkage and creep of concrete to the prestress of prestressed concrete structures (e.g. prestressed beam, track slab, sleeper, contact network column, etc.).
7 The durability design shall adopt new material, new process and new method which shall be tested and verified according to relevant requirements of the nation and the Ministry of Railways and may be used only after passing the examination and approval.
1.0.5 The durability design on concrete structure of railway shall not only comply with those specified in this code, but also comply with those specified in the current relevant standards of the nation.
2 Terminologies
2.0.1 Durability of concrete structure
The capacity of concrete structure and its members to maintain applicability and safety in the design working life under the intended functions and maintenance and service conditions.
2.0.2 Design working life
The target working life, with sufficient safety degree or guarantee rate, used by designers as structural durability design basis.
2.0.3 Cementitious material or binder
A generic term of cement and mineral additive for preparation of concrete.
2.0.4 Water to binder ratio
The mass ratio of total water consumption to total amount of binder in concrete mixture.
2.0.5 Deterioration
Progressive damage or failure of materials due to physical, chemical or electrochemical reactions with surrounding environmental factors, called as corrosion for steel materials.
2.0.6 Resistance coefficient to sulfate attack of binder
The ratio of breaking strength of mortar specimen for cement or binder soaked in certain concentration of sodium sulfate solution and that of mortar specimen soaked in clean water, for evaluating the resistance capability of cement or binder to sulfate attack.
2.0.7 Passed electric charge
The total electric charges passing through specified sectional area of concrete under certain conditions, for evaluating the inward infiltration of concrete against media such as water and ion.
2.0.8 Chloride diftusion coefficient
The parameter describing the diffusion process of chloride in concrete pore water from high-concentration zone to low-concentration zone, for evaluating resistance of concrete against chloride erosion.
