Understanding Concrete Properties: Plastic, Setting, and Hardened States, Slides of Reinforced Concrete Design

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CONCRETE

PROPERTIES

CONCRETE PROPERTIES

Three Different States of Concrete 1.Plastic State When the concrete is first mixed, it is like “bread dough”. It is soft and can be worked or moulded into different shapes. In this state, concrete is called PLASTIC. Concrete is plastic during placing and compaction The most important properties of plastic concrete are workability and cohesiveness. A worker will sink into plastic concrete

CONCRETE PROPERTIES

Three Different States of Concrete 3.Hardened State After concrete has set, it begins to gain strength and harden. The properties of hardened concrete are strength and durability. Hardened concrete will have no footprints on it if walked on.

WORKABILITY

WORKABILITY means how easy it is to:  (^) Place  (^) Handle  (^) Compact  (^) Finish the concrete

WORKABILITY

To make a more workable mix:  (^) Add more cement paste  (^) Use well-graded aggregates  (^) Use an admixture (admixtures that improve workability as known as plasticisers) Note: Never try to make a mixture more workable by just adding more water because this lowers the strength and durability of concrete

COHESIVENESS

COHESIVENESS is how well concrete holds together when plastic

STRENGTH AND DURABILITY

Well-made concrete is a naturally strong and durable material. It is dense, reasonably watertight (impermeable), able to resist changes in temperature, as well as wear-and-tear from weathering and traffic

STRENGTH AND DURABILITY

Strength and durability are affected by the density of the concrete. Denser concrete is stronger and more watertight (or less permeable). Concrete durability increases with strength. Well made concrete is very important to protect the steel in reinforced concrete. Strength of concrete in the hardened state is usually measured by the compressive strength using the Compression Test.

STRENGTH AND DURABILITY

 CURING

Curing is keeping concrete continuously damp for a period, allow it to reach maximum strength. Loner curing will give more-durable concrete

STRENGTH AND DURABILITY

 WEATHER

Weather will cause concrete to have a higher early strength

STRENGTH AND DURABILITY

 THE WATER TO

CEMENT RATIO

Too much water and not enough cement means concrete will be weaker and less durable

STRENGTH AND DURABILITY

The water to cement ratio (W/C) is the weight of water divided by the weight of cement. The lower the ratio, the stronger the concrete.