There are two types of systems considered in RAM Concept .

• Unbonded systems: greased strand encased in plastic sheathing.
• Bonded systems: bare strand within grouted ducts.

Strands are typically comprised of seven wires spirally wound. There are two dominant strand sizes used in building construction:

• 0.5 inch diameter (12.7 mm)
• 0.6 inch diameter (15.2 mm)

For further discussion on post-tensioning systems, see Chapter 26, "Defining Tendons".