Prestressed concrete structures

Claim 1

A SUBSTANTIALLY CORROSION RESISTANT CYLINDRICAL CONCRETE STRUCTURE COMPRISING AN ANNULAR WALL OF SUBSTANTIAL THICKNESS AND SUFFICIENT TO WITHSTAND FORCES APPLIED THERETO, A SERIES OF CONVOLUTIONS OF HIGH TENSILE STRENGTH TENDONS WRAPPED ABOUT THE OUTER FACE OF THE WALL UNDER SUB STANTIAL TENSION, SAID TENDONS BEING ELONGATED A DESIRED AMOUNT WHEREBY THE CONCRETE WALL IS PRESTRESSED AND CIRCUMFERENTIALLY COMPRESSED BY THE RADIAL PRESSURE EXERTED BY THE TENSIONED TENDONS, AND A PREFORMED, FLEXIBLE AND SCUFF AND ABRASIVE RESISTANT PLASTIC COATING COMPLETELY ENVELOPING EACH TENDON AND APPLIED THEREON BEFORE SAID TENDONS ARE WRAPPED AND TENSIONED ABOUT THE WALL, A PORTION OF SAID COATING BEING POSITIONED BETWEEN THE OUTER FACE OF THE WALL AND THE TENDON, SAID PLASTIC HAVING SUFFICIENT RESISTANCE TO EXTRUSION TO RESIST THE RADIAL FORCE DEVELOPED BY THE TENDON WHEREBY THE TENDON REMAINS ENVELOPED IN THE PLASTIC COATING UNDER SAID RADIAL FORCE.