19-3.02A General
Reserved
19-3.02B Cofferdam
Interior dimensions of cofferdams must provide enough space inside the wales for (1) form construction, (2) pile driving, and (3) pumping of water from outside the foundation forms.
No shoring is allowed in cofferdams that would induce stress, shock, or vibration in the permanent structure.
Structure backfill must be free of organic or other unsatisfactory material.
The impervious backfill material must be an authorized earthy material. The sand equivalent requirement does not apply.
Structure backfill compacted to a relative compaction of at least 95 percent and material placed behind retaining walls must have a sand equivalent value of at least 20 and comply with the gradation requirements shown in the following table:
Sieve size
|
Percentage passing
|
3"
|
100
|
No. 4
|
35–100
|
No. 30
|
20–100
|
Except for material placed behind retaining walls, structure backfill compacted to a relative compaction of at least 90 percent must comply with the gradation requirements shown in the following table:
Sieve size
|
Percentage passing
|
3"
|
100
|
Structure backfill for crib walls must comply with the requirements shown in the following tables:
Wall height
(feet)
|
Type of backfill material
|
Thickness of each layer of material before compaction (feet)
|
<10
|
C, D, or E
|
1
|
10–25
|
D or E
|
2
|
>25
|
E
|
4
|
Backfill
|
Gradation
|
|
|
material
type
|
Sieve
size
|
Percentage
passing
|
Sand
equivalent
(min)
|
Relative
compaction
(min, %)
|
C
|
3"
|
100
|
--
|
90
|
D
|
3"
|
100
|
30
|
90
|
|
No. 4
|
35–100
|
|
|
E
|
3"
|
100
|
--
|
90
|
|
No. 4
|
25–70
|
|
|
|
No. 50
|
5–20
|
|
|
|
No. 200
|
0–5
|
|
|
Material from structure excavation not suitable for use as structure backfill may be used to replace imported borrow or other excavated material.
Pervious backfill material must consist of one or any combination of the following materials:
1. Gravel
2. Crushed gravel
3. Crushed rock
4. Natural sand
5. Manufactured sand
Pervious backfill material must comply with the gradation requirements shown in the following table:
Sieve size
|
Percentage passing
|
2"
|
100
|
No. 50
|
0–100
|
No. 100
|
0–8
|
No. 200
|
0–4
|
The gradation for sacked pervious backfill material behind wall drain outlets must comply with the gradation specified for 1-1/2-by-3/4 inch primary aggregate in section 90-1.02C(4)(b).
A weep hole and geocomposite drain alternative must comply with section 68-7.
19-3.02E Slurry Cement Backfill
Slurry cement backfill must be a fluid workable mixture of aggregate, cement, and water.
The aggregate must be one of the following:
1. Commercial-quality concrete sand
2. Excavated or imported material in any combination, free of organic material and other deleterious substances and complying with the gradation requirements shown in the following table:
Sieve size
|
Percentage passing
|
1-1/2"
|
100
|
1"
|
80–100
|
3/4"
|
60–100
|
3/8"
|
50–100
|
No. 4
|
40–80
|
No. 100
|
10–40
|
The cement must comply with section 90-1.02B(2) except testing is not required.
The water must be free from oils, salts, and other impurities that adversely affect the backfill.
Proportion slurry cement backfill by weight or volume. The backfill must contain at least 188 pounds of cement per cubic yard and enough water to produce a fluid workable mix that flows and can be pumped without segregation during placement.
Mix materials thoroughly by machine. Use a pugmill, rotary drum, or other authorized mixer. Mix until cement and water are thoroughly dispersed.
You may use slurry cement backfill as structure backfill for pipe culverts.
19-3.02F Culvert Beddings 19-3.02F(1) General
Culvert beddings must be shaped bedding, sand bedding, or soil cement bedding.
If more than 1 type of bedding is allowed, use the same bedding for the entire length of the culvert.
19-3.02F(2) Sand Beddings
Sand bedding must consist of sand:
1. Free of clay or organic material
2. Suitable for the purpose intended
3. Complying with the gradation requirements shown in the following table:
Sieve size
|
Percentage passing
|
No. 4
|
90–100
|
No. 200
|
0–5
|
Material and mixing requirements for soil cement bedding must comply with the specifications for slurry cement backfill in section 19-3.02E except:
1. It must contain at least 282 pounds of cement per cubic yard
2. Aggregate must not be commercial-quality concrete sand
19-3.02G Controlled Low-Strength Material
If authorized, controlled low-strength material may be used as structure backfill for pipe culverts unless the culvert has a diameter or span of more than 20 feet.
Controlled low-strength material must be a fluid workable mixture of aggregate, cement, and water.
Cement must be one of the following:
1. Cement complying with ASTM C150
2. Blended hydraulic cement complying with either of the following:
2.1. ASTM C595
2.2. Physical requirements in ASTM C1157
When tested under ASTM D4832, the controlled low-strength material must have a 28-day compressive strength:
1. From 50 to 100 psi for pipe culverts with 20 feet or less in height of cover
2. Of at least 100 psi for pipe culverts with over 20 feet in height of cover
Water must be free of oil, salts, and other impurities that adversely affect the backfill.
Aggregate must be one of the following:
1. Commercial-quality concrete sand
2. Excavated or imported material in any combination, free of organic material and other deleterious substances and complying with the gradation requirements shown in the following table:
Sieve size
|
Percentage passing
|
1-1/2"
|
100
|
1"
|
80–100
|
3/4"
|
60–100
|
3/8"
|
50–100
|
No. 4
|
40–80
|
No. 100
|
10–40
|
Mix materials thoroughly by machine. A pugmill rotary drum or other authorized mixer must be used. Mix until cement and water are thoroughly dispersed.
Wherever controlled low-strength material is placed within the travelled way or covered by paving or embankment materials, the controlled low-strength material must achieve a maximum indentation diameter of 3 inches when tested under ASTM D6024 before covering and opening to traffic.
19-3.02H Concrete Backfill
Concrete backfill encasing steel soldier piles below the lagging must comply with section 90-1 and contain at least 505 pounds of cementitious material per cubic yard.
19-3.02I Lean Concrete Backfill
Lean concrete backfill must comply with the specifications for slurry cement backfill in section 19-3.02E except the aggregate must be commercial-quality concrete sand.
Filter fabric must be Class A.
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