A neat organic Portland cement grout comprises the annular material. It was selected for the following reasons:
High modulus of elasticity in compression (2.0 - 3.0 x 106 psi) and overall high compressive strength (8,000 - 10,000 psi). Deformation of the annular material translates into a hoop strain on the liner and relatively high compression values greatly restrict the magnitude of that stress.
Low shrinkage value - drying shrinkage of grout trapped between two impermeable forms is negligible. If required, additives can be mixed with the grout to expand its volume
Hydraulic set - external heat is not required to cure grout, a factor especially advantageous for field-installed repair projects.
Similar thermal expansion to steel.
Optimum flow properties.
2nd corrosion defense system - the high pH of the grout passivates steel and therefore acts as an inhibitor between the plastic liner and steel.
Economical and readily available - inorganic cement is still one of the least expensive materials in the market.