UFC 3-270-07
12 August 2002
2-2.4.3.8 Standing water in the crater must be pumped out, if possible.
2-2.4.3.9 Any reinforcing material protruding from the original pavement must be cut off
and removed.
2-2.4.3.10 Backfill the crater with useable debris and level to exactly 711 millimeters
(28 inches) below the original pavement surface.
2-2.4.3.11 Backfill material must be compacted to a minimum 4 CBR.
2-2.4.3.12 Install a 304-millimeter (12-inch) layer of crushed stone (38 millimeters [1.5
inches] minus) over the backfill material. Place and compact the crushed stone material
in lifts approximately 152 millimeters (6 inches) thick. Compact each lift of crushed
stone using a minimum of four passes of a single drum vibratory roller or two passes
with a 10-ton vibratory roller per each 152-millimeter (6-inch) lift. One pass of the roller
means traveling across and back in the same lane. If the crushed stone material is
placed upon soft subgrade materials, it may be beneficial to separate the crushed stone
from the backfill with a geomembrane and to place the crushed stone material in thicker
lifts. In any case, the crushed stone should be compacted with a minimum of four
passes of a single drum vibratory roller or two passes of a 10-ton vibratory roller per
each 152 millimeters (6 inches) of thickness. A 304-millimeter (12-inch) crushed stone
layer should receive a minimum of eight passes with a single drum vibratory roller, or
four passes with a 10-ton vibratory roller. This crushed stone material must be
compacted to a minimum 25 CBR.
2-2.4.3.13 Place a layer of sand approximately 304 millimeters (12 inches) wide by 25
to 50 millimeters (1 to 2 inches) deep around the entire inside of the crater's lip to
prevent seepage of the grout around the edge of the crater.
2-2.4.3.14 Position a layer of impervious membrane material over the entire crushed
stone surface.
2-2.4.3.15 Place a 203-millimeter (8-inch) layer of grout material mixed in accordance
with Table 2-2 into the crater.
Table 2-2. Stone and Grout Mix Proportions
Percentage by
Weight of Additive Per
Grout Mixture
Weight
Cubic Yard
Portland cement
67.8
22.3.2 lb (999.4 kg)
Calcium chloride
1
32.67 lb (14.8 kg)
(accelerator)
Friction retarder
0.2
6.68 lb (2.9 kg)
Water
31
1004.4 lb (455.6 kg)
Note: This mixture will develop a compressive strength of at least
1500 pounds per square inch (psi) in 24 hours
2-10
Previous Page
