Pumpable cement grout

Claim 1

A method for grouting an annular cavity formed intermediate a tubular external member having a longitudinal extent and an internal member disposed in said tubular external member, said method comprising: forming a pumpable cement grout, said grout comprising: portland cement; water in an amount sufficient so that the water-to-portland cement ratio of said grout is from about 0.6 to about 0.68 by weight; and pre-generated aqueous foam in an amount sufficient to adjust the wet density of said grout to a value of from about 55 to about 72 pounds per cubic foot; and pumping said pumpable cement grout into said annular cavity so that said grout fills said cavity by flowing in a generally longitudinal direction through said tubular external member.

Claim 2

A method for grouting an annular cavity formed intermediate a tubular external member having a longitudinal extent and an internal member disposed in said tubular external member, said method comprising: forming a pumpable cement grout, said grout comprising: portland cement; water in an amount sufficient so that the water-to-portland cement ratio of said grout is from about 0.6 to about 0.68 by weight; and pre-generated aqueous foam in an amount sufficient to adjust the wet density of said grout to a value of from about 55 to about 72 pounds per cubic foot; and pumping said pumpable cement grout into said annular cavity so that said grout fills said cavity by flowing in a generally longitudinal direction through said tubular external member.

Claim 4

A method for lining a pipe, said pipe having a longitudinal extent and a predetermined internal diameter, said method comprising: placing a tubular liner in said pipe, said liner having an external diameter such that an annular cavity is formed intermediate said pipe and said liner, said liner further having a tendency to collapse if subjected to an external pressure which is in excess of a predetermined maximum pressure; forming a pumpable cement grout, said grout comprising: portland cement; water in an amount sufficient so that the water-to-portland cement ratio of said grout is from about 0.6 to about 0.68 by weight; and pre-generated aqueous foam in an amount sufficient to adjust the wet density of said grout to a value of from about 55 to about 72 pounds per cubic foot; and injecting said pumpable cement grout under pressure into said annular cavity at a first point along said pipe, so as to fill said annular cavity by flowing said grout substantially longitudinally within said pipe away from said first point towards a second point along said pipe; and maintaining said pressure of said injection substantially at or below said predetermined maximum pressure during said injection.

Claim 5

A method for lining a pipe, said pipe having a longitudinal extent and a predetermined internal diameter, said method comprising: placing a tubular liner in said pipe, said liner having an external diameter such that an annular cavity is formed intermediate said pipe and said liner, said liner further having a tendency to collapse if subjected to an external pressure which is in excess of a predetermined maximum pressure; forming a pumpable cement grout, said grout comprising: portland cement; water in an amount sufficient so that the water-to-portland cement ratio of said grout is from about 0.6 to about 0.68 by weight; and pre-generated aqueous foam in an amount sufficient to adjust the wet density of said grout to a value of from about 55 to about 72 pounds per cubic foot; and injecting said pumpable cement grout under pressure into said annular cavity at a first point along said pipe, so as to fill said annular cavity by flowing said grout substantially longitudinally within said pipe away from said first point towards a second point along said pipe; and maintaining said pressure of said injection substantially at or below said predetermined maximum pressure during said injection.

Claim 9

A method for lining a subterranean sewer line, said sewer line having an internal diameter equal to or less than about 60 inches, said sewer line further having access to the interior thereof from the surface at least first and second manholes at longitudinally spaced apart points along said sewer line, said method comprising: placing a high density polyethylene pipe in said sewer line, said polyethylene pipe having an external diameter such that an annular cavity having a radial extent equal to or less than about 3 inches is formed intermediate said sewer line and said polyethylene pipe, said polyethylene pipe further having a tendency to collapse if subjected to an external pressure in excess of a predetermined maximum pressure equal to or less than about 10 pounds per square inch; forming a pumpable cement grout, said grout comprising: portland cement; water in an amount sufficient so that the water-to-portland cement ratio of said grout is from about 0.6 to about 0.68 by weight; and pre-generated aqueous foam in an amount sufficient to adjust the wet density of said grout to an value of from about 55 to about 72 pounds per cubic foot; forming a dam about said polyethylene pipe so as to seal said annular cavity between said pipe and said sewer line at said first access manhole, said dam having an injection port therethrough for establishing fluid communication between the surface and said annular cavity; pumping said cement grout under pressure into said annular cavity through said injection port so that said cement grout fills said annular cavity by flowing in a generally longitudinal direction through said sewer line from said first access manhole towards said second access manhole, said pressure under which said cement grout is pumped into said annular cavity being maintained about equal to or less than said predetermined maximum pressure; and terminating said pumping of said cement grout into said annular cavity when said flow of said grout through said sewer line reaches said second access manhole.

Claim 10

A method for lining a subterranean sewer line, said sewer line having an internal diameter equal to or less than about 60 inches, said sewer line further having access to the interior thereof from the surface at least first and second manholes at longitudinally spaced apart points along said sewer line, said method comprising: placing a high density polyethylene pipe in said sewer line, said polyethylene pipe having an external diameter such that an annular cavity having a radial extent equal to or less than about 3 inches is formed intermediate said sewer line and said polyethylene pipe, said polyethylene pipe further having a tendency to collapse if subjected to an external pressure in excess of a predetermined maximum pressure equal to or less than about 10 pounds per square inch; forming a pumpable cement grout, said grout comprising: portland cement; water in an amount sufficient so that the water-to-portland cement ratio of said grout is from about 0.6 to about 0.68 by weight; and pre-generated aqueous foam in an amount sufficient to adjust the wet density of said grout to an value of from about 55 to about 72 pounds per cubic foot; forming a dam about said polyethylene pipe so as to seal said annular cavity between said pipe and said sewer line at said first access manhole, said dam having an injection port therethrough for establishing fluid communication between the surface and said annular cavity; pumping said cement grout under pressure into said annular cavity through said injection port so that said cement grout fills said annular cavity by flowing in a generally longitudinal direction through said sewer line from said first access manhole towards said second access manhole, said pressure under which said cement grout is pumped into said annular cavity being maintained about equal to or less than said predetermined maximum pressure; and terminating said pumping of said cement grout into said annular cavity when said flow of said grout through said sewer line reaches said second access manhole.