Table 8-2.1
A Summary of Densification Methods for Building Foundations
Soil
Soil
Degree of
Fill and Backfill
Deep Foundation Deposits
Group
Types
Compaction
Typical Equipment and Procedures for Compaction
Field
Compaction Methods
Field Control
Control
Equipment
No. of
Lift
Placement
Phases or
Thick.,
Water
Coverages
mm (in)
Content
(A) Surface compaction by equipment
GM
90 95%
Rubber tired
2-5
200 (8)
Optimum
Control
and procedures shown @ left is feasible
ASTM D 1557
roller (a)
coverages
water
samples at
GC
only if material is at proper water
maximum
content
intervals to
Sharpefoot
4-8 passes
150 (6)
content.
density
based on
determine
SM
roller (d)
ASTM D
degree of
(B) Densification of soils is controlled by
SC
1557
compaction
Power hand
Indefinite
100 (4)
consolidation process:
ML
tamper ( c )
Preload fills*
(A) Optimum
CL
(A) Control
85-90%
Rubber tired
2-4
250 (10)
water content
Lowering of groundwater table
samples as
ASTM D 1557
roller (a)
coverages
based on
OL
ASTM D 1557.
noted
maximum
Drying
OH
above, if
density
___________________________
(B) Wet side
Sharpefoot
4-8 passes
200 (8)
needed.
maximum
MH
* Consolidation may be accelerated by
roller (d)
water content
(B) Field
means of vertical drains.
at which one
CH
control
Crawler
3
150 (6)
material can
Field control exercised by observation of
satisfactorily
exercised
type tractor
coverages
pore pressures and surface settlements.
operate,
by visual
(b)
minimum water
inspection
content
of action of
Power hand
Indefinite
150 (6)
required to
bond particles
compaction
tamper (d)
(and not result
equipment.
in voids or
Control of
Indefinite
150
honey-combed
materials.)
construction
200 (6-
equipment
8)
Note: The above requirements will be adequate in relation to most construction. In special cases where tolerable settlements are unusually small, it may be necessary to employ additional
compaction equivalent to 95-100% of CE55 compaction effort. A coverage consists of one application of the wheel of a rubber tired roller of the treads of a crawler type tractor over each
point in the area being compacted. For a sharpefoot roller drum over the area being compacted.
a. Rubber tired rollers having a wheel load between 18,000 and 25,000 lbs. and a tire pressure between 80 and 100 psi.
b. Crawler type tractors weighing not less than 20,000 lbs and exerting a foot pressure not less than 6 psi.
c. Power hand tamper weighing more than 100 lbs: pneumatic or operated by gasoline engine.
d. Sharpfoot rollers having a foot pressure between 250 and 500 psi and tamping 7-10 tamp lengths with a face area between 7 and 16 sq. inches.
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