civil engineering-->>How prestressed concrete is made

How prestressed concrete is made


1. It all begins at the prestressed concrete plant.	2. This is called a prestressing strand. Made of high strength steel, it will soon be embedded in concrete.

3. The prestressing strand is stretched across the casting bed. About 30,000 pounds of tension will be applied to the cable before it's surrounded by concrete. Why? Hold a rubber band loosely between two fingers. Now stretch your fingers farther apart. See how the rubber band becomes taut and more resistant to downward pressure? The same principle holds true for prestressing strands.	4. Cement, sand, stone, and water make up concrete.


5. Special trucks bring the concrete to the casting bed where the pouring begins.	6. Once the pouring is complete, a tarp is placed over the form and heat is applied to cure the cement.

7. The prestressing strands are cut and the concrete form is removed from the casting bed.	8. The ends are cleaned and the prestressing strands are sealed with a protective coating.


9. The end-product is shipped to a building site.

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