Concrete Technology (General Engineering) (SSC JE)

Rich mixes are less susceptible to bleeding than lean mixes.
• Richer mixes may have more adverse effect than that of lean mixes.

• Generally, high strength concrete or rich concrete is adversely affected by the use of large size aggregate, but in lean mixes or weaker concrete the influence of
size of the aggregate gets reduced.

Deleterious materials in aggregate– The materials whose presence in aggregate may adversely affect the strength, workability and long termed performance of concrete are termed as deleterious materials.

• These are considered undesirable constituents. The total amount of deleterious materials in aggregate should not exceed 5% as per IS 383-1970.

Durability of concrete–
• Durability of concrete is its capacity to resist the forces of disintegration owing to natural causes such as weathering, action of water containing chemicals, temperature changes including freezing and thawing, alterations in moisture content and chemical changes.

• The durability of concrete is proportional to cementaggregate ratio.

Fiber reinforced concrete having ductility property so it can be exhibits better toughness property and can be used in structure subjected to fatigue load.