Complete the sentences by filling in the correct word that fits a statement (gap fill). Choose the appropriate words from the word bank given below.
A. tensile B. materials C. threaded D. curing
E. conduits F.groutedG. unskilled H. applications
I. inexpensive J. to compensate K. pre-tensioned L. released
1. Portland cement concrete is a strong, dependable, and relatively …… construction material.
2. When fully hardened the clamps are …… and the stress is transferredwithin the rigid concrete.
3. Unbonded post-tensioning is accomplished by coating the …… elements with lubricant and covering them with extruded polymer sleeves.
4. When …… is complete the tensile elements can be pulled into tension and clamped to the embedded anchors at the edges of the piece.
5. Bonded post-tensioning utilizes …… placed into the concrete molding form.
6. Lighter, stronger, longer lasting, and requiring fewer joints, pre-stressed concrete construction …… have shown how good stress can be.
7. Pre-stressed concrete has led to an explosion of …… in buildings, bridges, slabs, foundations, and roadways.
8. In …… concrete tensile elements are clamped under calculated tensile stress.
9. The tensioning elements are …… through the conduits before the concrete is cast.
10. The tensioning elements are then …… into place at the openings to permanently bond them with the structural casting.
UNIT 11
Post-Tensioned Slabs
Read, translate the following text and be ready to fulfil the tests:
Post-tensioning is a method of reinforcing concrete that enables a designer to take advantage of the considerable benefits provided by pre-stressed concrete while retaining the flexibility afforded by the cast-in-place method of building concrete structures. The first application of post-tensioning is believed to have been conceived by Eugene Freyssinet in 1933 for the foundation of a marine terminal in France and the technology was introduced to the United States in the 1950s. Post-tensioning now is used extensively in bridges, elevated slabs (parking structures and residential or commercial buildings), residential foundations, walls and columns.
Post-tensioning is simply a method of producing pre-stressed concrete, masonry, and other structural elements. The term pre-stressing is used to describe the process of introducing internal forces (or stress) into a concrete or masonry element during the construction process in order to counteract the external loads applied when the structure is put into use (known as service loads). These internal forces are applied by tensioning high-strength steel, which can be done either before or after the concrete is placed. When the steel is tensioned before concrete placement, the process is called pre-tensioning. When the steel is tensioned after concrete placement, the process is called post-tensioning. Because pre-tensioning requires specially designed casting beds, it is used generally in the precast manufacturing process to make simple shapes that can be trucked to a jobsite. Post-tensioning is done onsite by installing post-tensioning tendons within the concrete formwork in a manner similar to installing rebar.