Use of fly ash slurry for underground facility construction

Abstract This paper presents the results of research performed in developing and using flowable fly ash slurry which falls under the classification of Controlled Low-Strength Material ( CLSM ) as defined by ACI Committee 229 for undergoing facility construction and abandonment. The mix proportions for the CLSM described in this paper utilized fly ash as a primary ingredient that was produced at Wisconsin Electric's Port Washington Power Plant as a by-product of burning coal from Pennsylvania. Additional ingredients included Portland cement, water, and conventional fine and coarse aggregates. The Port Washington Power Plant has four 80 MW electric generating units that were brought into service between 1935 and 1949. Information is also included on CLSM'S compressive strength, electrical resistivity, thermal conductivity and compatibility with plastics used in the manufacture of underground electric cable jackets and natural gas lines. The results indicate that CLSM fly ash slurry is an excellent material for backfilling trenches and filling abandoned underground facilities.