Hole Design for Concrete

General Concepts For Breaking Of Concrete

d 32 - 35 mm
1½ " - 1¾ "
L 40 - 60 cm
1´ 4" - 2´
D 70% of Height
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When vertical drilling is difficult, drill horizontal holes with some slope.

Reinforced Concrete

d 35 mm 38 - 44 mm
1 3/8" 1 ½" - 1 ¾"
L 20 - 25 cm 30 - 40 cm
8" - 10" 1'-1'4"
D 90% of Height
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d and L depend on both quantity and shape of the reinforced steel.

Thin Concrete

(1) SQUARE ARRANGEMENT
d 32 - 38 mm
1 ¼" - 1 ½"
L 25 - 30 cm
10" - 1'
D Almost Wall Thickness
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Crack width of the front row is opened much larger than that of the behind rows.
(2) AVOIDING DIAGONAL CRACKING
d32 - 38 mm25 mm32 - 38 mm
1 ¼"-1 ½"1"1 ¼" - 1 ½"
L25 - 30 cm10 cm10 - 15 cm
10" - 1'4"4"-6"
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The curvature at corner (R) should be more than 15 cm (6').
(3) SPLITTING OF WALLS
d38 - 44 mm
1 ¼" - 1 ½"
L25 - 30 cm
10" - 1'
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(4) SPLITTING OF SLABS
d38 - 44 mm
1 ½" - 1 ¾"
L25 - 30 cm
10" - 1'
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(5) ESTABLISHING FREE SURFACES
d38 - 44 mm
1 ½" - 1 ¾"
L25 - 30 cm
10" - 1'
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Instead of Burn Cut, cross drilling may be used to establish the free surface for wall case.

Mass Concrete

 Concrete Reinforced Concrete
d38 - 51 mm38 - 44 mm
1 ½" - 2"1 ½" - 1 ¾"
L50 - 90 cm40 - 60 cm
1'8" - 3'1'4" - 2'
...

Pile Foundation

d38 - 44 mm
1 ½"-1 ¾"
L120 cm
8"
L220 - 25 cm
8" - 10"
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Thick Wall

d38 - 44 mm
1 ½" - 1 ¾"
L30 - 60 cm
1' - 2'
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Cracks propagate along wall face

When perpendicular cracks to wall face are necessary:

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(1) Add a reliever hole. Spacing may be 10 cm (4') through 20 cm (8'). (2) Drill larger diameter holes

Pier / Bridge / Foundation

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Drilling pattern depends on the shape of the structure and the site situation.

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(1) Making of large block; Secondary breaking with large rock breaker
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(2) Making of small pieces; Drilling is only from one side.
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(3) Wall is very high; Vertical drilling is difficult
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(4) Foundation is thick, Secondary breaking with large rock breaker.

Zone Demolition

(1) STAGGERED ARRANGEMENT (PILLAR)
d38 - 44 mm
1 ½" - 1 ¾"
L30 - 40 cm
1' - 1'4"
D90% of Width or Height
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(2) X FIGURE ARRANGEMENT (PILLAR, WALL)
d38 - 44 mm
1 ½" - 1 ¾"
L30 - 40 cm
1' - 1'4"
D90% of Width or Height
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(3) CROSS DRILLING (BEAM)
d38 - 44 mm
1 ½" - 1 ¾"
L30 - 40 cm
1' - 1'4"
D90% of Width or Height
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Delayed Filling

Fill in (1) holes then (2) holes after a suitable delay.
This can be applied for controlling the cracking direction (See below).

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FIGURE 1: SPLITTING OF LARGE BOULDER
d32 - 35 mm 44 - 51 mm
1 ¼" - 1 3/8" 1 ¾" - 2"
L30 - 40 cm 60 - 90 cm
1' - 1'4" 2' - 3'
D70% of Height
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FIGURE 2: TRENCHING AND TUNNELING OF ROCK
d38 - 51 mm
1 ½" - 2"
L30 - 60 cm
1' - 2'
D1 - 1.8 m
3' - 6'
45°-60°
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Reliever holes are necessary when trench is deep
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Repeat the same procedure for deeper case
FIGURE 3: MASS CONCRETE
 ConcreteReinforced Concrete
d38 - 51 mm 38 - 44 mm
1 ½" - 2" 1 ½" - 1 ¾"
L50 - 90 cm 40 - 60 cm
1'8" - 3' 1'4" - 2'
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