Material properties of high volume fly ash cement paste structural fill

Abstract

Fly ash can be effectively used as compacted or flowable fill material in the construction of structural fills for building foundations, embankments, base and subbase courses for highways and railroads, dikes, levees, bridge abutments, and landfill cover in lieu of conventional earth materials. In this study, high volume fly ash cement paste composite formed of various combinations of fly ash, cement, lime, silica fume, and chemical admixtures has been examined in terms of its physical (dry unit weight, void ratio, apparent specific gravity, linear shrinkage), mechanical (unconfined compressive strength, flexural strength), and durability properties (hydraulic conductivity, soundness by use of sodium sulphate) at 0, 100, and 200 mm slump values. The results indicate that the cement paste, providing certain advantages over conventional fill materials with its lower unit weight, higher strength, and higher volume stability can be designed for any required engineering performance for use in the construction of compacted to self-compacting structural fills and promises high volume fly ash utilization with low technology requirements avoiding scarce use of raw resources.