A cement produced by Gilsonite is suitable for blocking or plugging an abandoned pipeline or back filling a mine shaft, tunnel or excavations contains Portland cement or a mixture of at least two components selected from Portland cement, A cementitious slurry, formulated from the cement mix, may have a density less than or equal to 1500 kg/m3, and exhibits good compressive strength.

In the formulation of the cementing composition of the invention, it is preferable to employ gilsonite in an amount ranging from approximately one-half to approximately ten times by volume the amount of the cement utilized, depending upon the particular result desired.

The lower range is employed where maximum strength is important; the higher range where the various qualities imparted by the gilsonite are most important.

Particle size and particle size distribution of the gilsonite determine the strength and porosity-permeability characteristics of the set cement for any given mix ratio.