RAPID-SETTING FLOWABLE BACKFILL COMPOSITION AND METHOD OF USING

摘要

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.