There are five levels of environment exposure of concrete for which durability requirements of concrete depends. These are: Mild exposure Moderate exposure Severe exposure Very severe exposure, and Extreme exposure. These are the environments to which the concrete will be exposed during its working life. The durability requirement, like clear cover to reinforcement steel is(…)
Concrete Durability
CHLORIDE ATTACK ON CONCRETE STRUCTURES
Chloride Attack on Concrete Structures: Chloride attack is one of the most important aspects for consideration when we deal with the durability of concrete. Chloride attack is particularly important because it primarily causes corrosion of reinforcement. Statistics have indicated that over 40 per cent of failure of structures is due to corrosion of reinforcement. Due(…)
CARBONATION OF CONCRETE STRUCTURES
Carbonation of concrete Structures The microstructure of concrete is such that it has capillary pores to the extent of 28%. The extent of pores depends upon quality of concrete and the presence of water at the time of mixing of concrete. Making more dense concrete with less water/cement ratio reduces the amount of pores. These(…)
TEMPERATURE EFFECTS ON CONCRETE
THERMAL MOVEMENT IN CONCRETE As with any material, concrete will expand and contract as the temperature rises and falls. The size of movement depends upon the change in temperature and the coefficient of thermal expansion o f concrete. The coefficient of thermal expansion of concrete is influenced largely by the coefficient of thermal expansion of(…)
REINFORCEMENT CORROSION-CAUSES & PREVENTION
REINFORCEMENT CORROSION-CAUSES & PREVENTION The corrosion of steel reinforcement is complex, but basically it is an electro-chemical reaction similar to that of a simple battery. The composition of mild steel varies along its length and potential anodic (more negatively charged) and cathodic (positively charged) sites can be set up at various points. Concrete is capable(…)
ACHIEVING DURABILITY FOR CONCRETE STRUCTURES
Achieving durability for concrete structures: The durable concrete structures are to be conceptualized, specified, designed, contracted, constructed and maintained. To achieve the design life of the structure at reasonable maintenance cost, the following aspects are required to be taken care of: i) The structure should also be designed for environment loads and detailing done. ii) (…)
COLD JOINT IN CONCRETE
What is Cold Joint in Concrete? An advancing face of a concrete pour, which could not be covered by fresh concrete before expiry of initial setting time (due to an unscheduled stoppage or delay on account of breakdown in plant, inclement weather, low rate of placement or any other reason), is called a cold joint.(…)
DESIGN OF CONCRETE STRUCTURES FOR DURABILITY
Design Engineers consider design of concrete structures to mean assessing: i) The size and strength of structural components and concrete strength grade to meet safety and serviceability limits. ii) The amount, size and distribution of reinforcements for strength and control cracks to an acceptable size. It is anticipated that with good site control and good(…)
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