Concrete


 * //Some definitions://**


 * Concrete** is a manufactured mixture of cement and water, with aggregates of sand and stones
 * First concrete-shell construction ** permits the erection of vast vaults and domes with a concrete and steel content so reduced that the thickness is comparatively less than that of an eggshell.

The second development, **precast-concrete construction**, employs bricks, slabs, and supports made under optimal factory conditions to increase waterproofing and solidity, to decrease time and cost in erection, and to reduce expansion and contractions.

Finally, **prestressed concrete** provides bearing members into which reinforcement is set under tension to produce a live force to resist a particular load. **//Differences among tiltwall, tilt-up panel and precast concrete construction//**

Tilt-up panel and tiltwall describe the same process. For a tilt-up concrete building, the walls are created by assembling forms and pouring large slabs of concrete called panels directly at the job site. The panels are then tilted up into position around the building's slab. Because the concrete tiltwall forms are assembled and poured directly at the job site, no transportation of panels is required. Tiltwall panels can sometimes be extremely wide and/or tall.

The precast concrete building process is similar to tilt-up construction. But the main difference is that concrete workers pre cast concrete panels at a large manufacturing facility. This activity can take place regardless the weather conditions. For a precast construction project, the panels must be smaller and more manageable to be able to transport them to their destination.

**Conclusion:** the concrete in its pure form is very strong in compression but no so much in resisting tension. That’s why we have other concrete alloys, like reinforced concrete, that suppress this original weakness. Besides, concrete is cheap, fire-water proof and is also it’s easy to shape into various kinds of forms.


 * Pre cast concrete- Prestressed concrete**

** Concrete Shell--- Reinforced concrete**