Talk:Prestressed concrete

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I wonder if in this article, it should be mentioned that...

Two of the forms in which prestressed concrete is often cast, include piles, slabs, hollow-core floors and girders, most of which conform to AASHTO [link] standards.

Piles are designed to be driven into the earth much as a hammer drives a nail, and must withstand strong shock forces.

Slabs are used to support great weights, and often exposed to high bending moments; thus prestressing the concrete can increase the maximum supportable weight.

Hollow-core (link to precast concrete ŝmention of hollow core) floors are cast using a low-slump mix, and cut up at the factory site.

AASHTO girders are classified according to type number and shape.

The shapes can range from I beams, to "Bulb-T" girders, so named for a cross section that looks like a T, and Double-T girders.

1 Merging
2 post-tensioned concrete
3 Diagrams
4 History

[edit] Merging

This article on prestressed concrete has much more depth than the post-stressed article, and both are about almost identical procceses. Enelson 23:12, 30 April 2006 (UTC)enelson

[edit] post-tensioned concrete

Q. I dont quite follow the description of the post-tensioned processes, especially unbonded. At what point to the tendons engage the cured concrete? Could someone please provide some diagrams, photos or a good link for this?

A. The tendons do not engage the concrete, they are unbonded from the concrete, hence the name.

a. That is true. Also the tendons pull the concrete shape from the ends where the tension is applied by jacks. the shape may be forced into a camber from the tensioning. Bond with the tendons is un-necesary. —Preceding unsigned comment added by 170.63.96.108 (talk) 18:03, 6 December 2007 (UTC)

I put some pictures in the article. One picture shows rolls of cable with the holding end anchors. These anchors are fastened to rebar and buried in the concrete locking one end. At the other end the coating is stripped from the cable and the cable is passed through the pulling end anchor attached to the inside of the form. After the concrete has cured the cable is stretched with a hydraulic jack. The cable is greased so that it will slide within the plastic sheathing. 24.19.45.169 (talk) 21:49, 9 March 2008 (UTC)