Volume 26, Issue 4 (December 2003)
Mechanical Behavior of a Pulverized Fly Ash Grouted Sand
A laboratory investigation was conducted in order to develop a new grout based on pulverized fly ash. Pulverization of a selected Greek fly ash yielded a gradation with D15 = 1.3 µm, D50 = 6 µm, and D85 = 20 µm and Blaine specific surface approximately equal to 8300 cm2/g. Suspensions of this pulverized fly ash, improved with additives, have comparable properties to ordinary and microfine cement suspensions. Suspensions were injected into clean sands. Permeability, UU, and CU-PP triaxial compression tests were conducted on the grouted specimens. The coefficient of permeability of the sands is reduced by 4 to 7 orders of magnitude. Grouting increases the stiffness and reduces the deformability of the sands. The Mohr-Coulomb failure criterion represents adequately the behavior of the grouted sands, yielding cohesion values ranging from 290 to 450 kPa and angle of internal friction values up to 5° higher than those of the clean sands. The shear strength parameters vary with axial strain, attaining their final values well before failure.