Concrete is a building material and opposing to beliefs, cement and concrete are not the same. In fact, cement is a component of concrete. Practically, speaking the three basic components of concrete are cement, water and aggregate. The aggregate includes rock, gravel or sand. Cement is in the powder form and works as a binding agent on getting mixed with aggregates and water. This concrete mix combination is poured to harden so that it is a durable material.
Salient features
- Basically, concrete is a mixture of rocks and aggregates paste. This paste helps in coating the surface of fine and coarse aggregates. This paste undergoes hydration, a chemical reaction and acquires strength to form concrete, a rock like mass.
- The remarkable trait is the key of concrete, it is malleable and plastic when mixed new, yet is hardened strong and durable. These excellent features or qualities makes concrete the most chosen material to build our homes or work places, sidewalks, dams, bridges, skyscrapers and superhighways.
Importance of Proportioning
Achieving durable, strong concrete depends on the ingredients proportioning mixed. A mixture that has less cement paste cannot fill the voids between aggregates and results in producing porous concrete and rough surfaces. On the other hand, a mixture with cement paste in excess is easy to place and offers a smooth surface, but the concrete can easily crack.
The paste quality determines the quality of the concrete. Concrete in high quality is produced when the water to cement ratio is less. This allows proper placing, curing, fresh concrete workability and consolidation.
A mixture that is designed properly possesses the workability desired for a fresh concrete and also offers the hardened concrete, the strength and durability. Typically, a mix with cement in 10 to 15 percent, aggregate of 60 to 75 percent and water to 15 to 20 percent is right. Thus, the entrained air takes up to 5 to 8 percent in many concrete mixes.