Table 3.

αbond values for sand suggested by the FHWA manual (FHWA, 2005)

DescriptionGrout-to-ground bond ultimate strength: kPa
Type AType BType CType D
Sand (some silt) (fine, loose−medium dense)70–14570–19095–19095–240
Sand (some silt, gravel)95–215120–360145–360145–385

Type A: Gravity grout only.

Type B: Pressure grouted through the casing during casing withdrawal.

Type C: Primary grout placed under gravity head, then one phase of secondary ‘global’ pressure grouting.

Type D: Primary grout placed under gravity head, then one or more phases of secondary ‘global’ pressure grouting.

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