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Permeability in concrete is studied towards providing for, or guarding against, which of the following features? 1. The penetration by materials in solution may adversely affect the durability of concrete; moreover, aggressive liquids 'attack' the concrete. 2. In the case of reinforced concrete, ingress of moisture and air will result in corrosion of steel leading to an increase in the volume of steel, resulting in cracking and swilling of the concrete cover. 3. The moisture penetration depends on permeability and if the concrete can become saturated with water it is less vulnerable to frost action.

Permeability in concrete is studied towards providing for, or guarding against, which of the following features? 1. The penetration by materials in solution may adversely affect the durability of concrete; moreover, aggressive liquids 'attack' the concrete. 2. In the case of reinforced concrete, ingress of moisture and air will result in corrosion of steel leading to an increase in the volume of steel, resulting in cracking and swilling of the concrete cover. 3. The moisture penetration depends on permeability and if the concrete can become saturated with water it is less vulnerable to frost action. Correct Answer 1 and 2 only

Concrete is a porous structure and therefore, certain chemicals such as organic acids (Acetic acid, lactic acid, butyric acid) and sulphates of calcium, sodium, and magnesium attacks the concrete. These chemicals either lead to change in the volume of concrete or gradually corrode concrete.

Hence, Statement ‘1’ is true.

Moist air may contain harmful salts such as calcium salts which are responsible for corrosion of steel in RCC if enters inside concrete due to its porosity which in turn reduces the concrete cover.

Hence, Statement ‘2’ is also true.

Permeability means how much ease water can flow inside the concrete. It depends on the size of voids inside concrete. Larger the size of voids, Higher the permeability.

Frost action means alternating freezing and drying. When the temperature falls below 00 C, water present inside concrete freezes and converts to ice. Since, ice has more volume than liquid water, therefore, ice tries to expand but there is not space available for expansion and hence, cracks appear on concrete.  This becomes more vulnerable when concrete is fully saturated with water.

Hence, Statement ‘3’ is False.

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