| abstract |
A polymer concrete pipe liner is formed from a fluidized, but substantially waterless cement containing mixture applied to the pipe interior. The mixture is composed of inorganic cement particles, a liquid styrene mixture and a minor amount of one or more poly-olefinically unsaturated co-monomers. The mixture substantially excludes acrylonitrile and acrylamide. The co-monomers are preferable selected from a group including trimethylolpropane-trimethacrylate, divinyl benzene, hexadiene, and polyvinylsiloxanes. Mixing the liquid and solid components forms a slurry which is transferred to a pipe interior. Transfer properties can be controlled by particulate gradation, dissolved polymers, and rheology control additives. The pipe is then spun to centrifugally cast the liner. The composition avoids the need for high temperature curing and toxic reactive unsaturates to co-polymerize and cross-link polystyrene. Like the current polymer concrete materials, the materials embodied in the present invention have adequate strength at geothermal operating temperatures and reduced permeability, but they achieve this result without either a significant loss of broad spectrum chemical resistance to harsh geothermal environments or a large increase in cost. Other embodiments also incorporate the use of pozzolanic solids and high alumina cement to further improve chemical resistance characteristics. |