Prestressed concrete is a form of concrete that is significantly prestressed or tensioned during production. It is a structural building technique that tolerates calculated engineering stresses to be placed in locations to offset the loads. This is a combination of the high strength compressive strengths of concrete and the high tensile strength of steel when tensioned. First introduced in the late-nineteenth century by a civil structural engineer by the name of Eugene Freyssinet in France, this technique was implemented in such a manner that it strengthened concrete against tensile forces which occurred when in use. Since then, the prestressed concrete technique installation has only grown worldwide and is used internationally.
There are two types of prestressed concrete we at Deputy Special Inspection San Diego are familiar with and that is pre-tensioned and post-tensioned. These tendons can be tensioned as either a mono-strand (each strand of wire is stressed individually) or multi-strand (all wires or strands in a tendon are stressed simultaneously). Tendons may be located either within the concrete or entirely outside of the concrete. While pre-tensioned concrete uses tendons directly embedded in the concrete, post-tensioned concrete can be used either or. We will go over a portion of this to give you and any potential clients that are reading this now an awareness of prestressed concrete.
Pre-Tensioned Concrete Deputy Special Inspections
Pre-tensioned concrete is a form of prestressed concrete where the tendon strands are stressed before concrete is cast. When the concrete finally cures with the tendons still under tension, the dead-end anchoring of these strands are released causing the tension to be transferred to the concrete. Pre-tensioned concrete is most commonly used for the fabrication of slab floors, balconies, structural beams, lintels, water tanks, concrete pipes, etc.
Pre-tensioning is a typical prefabrication technique where a final concrete portion or segment is made remotely and transported to a site and erected once cured. This allows multiple segments to be built from beginning to end which can be very convenient in locations where cast in place concrete and post tensioned operations are not practical.
Post-Tensioned Concrete Deputy Special Inspections
Post-tensioned concrete is another type of prestressed concrete where the tendons are tensioned after concrete has been cast. It is essential that concrete must reach a minimum psi (typically noted on the approved structural plans) prior to stressing to reduce any damage of newly installed concrete or any potential danger of fatally injuring nearby workers or pedestrians. In order to confirm that concrete has reached a minimum psi, concrete cylinder samples are taken during placement. These same samples are transported to the lab and tested. We are aware that some projects request early breaks in order to strip forms and start building the next portion of their project. We at Deputy Special Inspection San Diego are willing and able to provide you these services.
Deputy Special Inspections San Diego Stressing Operations
At Deputy Special Inspections San Diego, we understand that whether it be prestressed, pre-tension, post-tension or soil nail stressing, calibration sheets are to always be verified prior to work being started. You can count on us to get your project done right the first time!