The following minimum design parameters of the mortar material were used for these calculations:
• minimum 3,000 psi compressive strength in first 24 hours
• minimum 150,000 psi modulus of elasticity in first 24 hours
• extremely dense to prevent water migration (levels less than 1,000 coulombs)
Allowances can be made for materials of lesser physical properties by proportionately increasing the liner thickness.
When a measurable thickness of the original wall has been lost, the new structural liner should be replaced with a thickness equal to that cross sectional value that was lost. For example, a pre-cast concrete manhole with an original cross sectional thickness of 5 inches (130 mm) which has lost 1.5