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AssigneeAmerican Electric Power Service Corporation
InventorsBruce H. Bennett, Gary J. Jablonski, Michael Bahleda, Claude W. Frishette, II, Paul R. Stodola
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The subject invention relates to a rapid-setting self-hardening backfill composition and method of installation. The composition comprising a minor amount of Class C fly ash as a primary constituent and other filler materials such as Class F fly ash in major amount. When such materials are combined with water in controlled amount, they produce a backfilling material which is flowable and self-leveling for easy installation in utility trenches and similar excavations in street and roadway surfaces to support relatively heavy compressive loads within relatively short periods of time without settling. The self-hardening initially flowable mixtures attain considerable strength for withstanding traffic loads without undue settling in time periods of about 4 hours. The rapid-setting of the composition provides a rapidly attainable strength of the order of about 20 psi within about 4 hours to permit overlaying a wearing course of paving material and reopening of excavated areas of streets and roadways without undue traffic delays and congestion. The backfilling composition ranges in amount from about 2 to 10 parts by weight filler material to about 1 part by weight Class C fly ash with sufficient water to react with both Class C fly ash and filler material. The composition utilizes by-products of coal-fired power stations to form a most economical backfilling material and method of utilization to provide both early strength and precisely controlled permanent strength to permit ready reexcavation.
A rapid-setting self-hardening flowable backfill composition consisting essentially of a combined mixture of filler material in major amount, Class C fly ash in minor amount, said filler ranging in amount from about 2 to 10 parts by weight to about 1 part by weight Class C fly ash, and sufficient water to react with said Class C fly ash and said filler material to form a self-leveling non-settling flowable material for backfilling introduction into excavated areas of roadways having sufficient early strength to withstand placement of a paving course overlay and subsequent exposure to normal roadway traffic loads within about four (4) hours.
A rapid-setting self-hardening flowable backfill composition comprising a combined mixture of Class F fly ash in major amount and Class C fly ash in minor amount, said Class F and Class C fly ashes ranging from about 2 to 10 parts by weight Class F fly ash to about 1 part by weight Class C fly ash, and sufficient water to react with both said Class F and Class C fly ashes, the ratio of said total solids to water being about 2.3 to 1 parts by weight, said composition being measured and intimately intermixed immediately prior to self-leveling flowable introduction of said composition into excavated roadway areas as a non-settling backfill material having an initial unconfined compressive strength of about 20 psi within about 4 hours.
The method of backfilling excavated trenches in roadways comprising the steps of intimately combining and intermixing a rapid-setting self-hardening flowable backfill composition said composition consisting essentially of filler material in major amount, Class C fly ash in minor amount, said filler material ranging in amount from about 2 to 10 parts by weight to 1 part by weight Class C fly ash, and sufficient water to react with said Class C fly ash and said filler material to form a flowable non-settling backfilling material having sufficient early strength to withstand placement of a paving course overlay and subsequent exposure to normal roadway traffic loads, and introducing said flowable backfilling material in self-leveling relation into excavated areas of roadways, said backfilling material having an initial unconfined compressive strength of about 20 psi within about four (4) hours.
Dependencies are inferred from the claim text.