Hole Design for Concrete

General Concepts For Breaking Of Concrete

d	32 - 35 mm
d	1½ " - 1¾ "
L	40 - 60 cm
L	1´ 4" - 2´
D	70% of Height

When vertical drilling is difficult, drill horizontal holes with some slope.

Reinforced Concrete

d	35 mm	38 - 44 mm
d	1 3/8"	1 ½" - 1 ¾"
L	20 - 25 cm	30 - 40 cm
L	8" - 10"	1'-1'4"
D	90% of Height

d and L depend on both quantity and shape of the reinforced steel.

Thin Concrete

(1) SQUARE ARRANGEMENT
d	32 - 38 mm
d	1 ¼" - 1 ½"
L	25 - 30 cm
L	10" - 1'
D	Almost Wall Thickness

Crack width of the front row is opened much larger than that of the behind rows.

(2) AVOIDING DIAGONAL CRACKING
d	32 - 38 mm	25 mm	32 - 38 mm
d	1 ¼"-1 ½"	1"	1 ¼" - 1 ½"
L	25 - 30 cm	10 cm	10 - 15 cm
L	10" - 1'	4"	4"-6"

The curvature at corner (R) should be more than 15 cm (6').

(3) SPLITTING OF WALLS
d	38 - 44 mm
	1 ¼" - 1 ½"
L	25 - 30 cm
	10" - 1'

(4) SPLITTING OF SLABS
d	38 - 44 mm
	1 ½" - 1 ¾"
L	25 - 30 cm
	10" - 1'

(5) ESTABLISHING FREE SURFACES
d	38 - 44 mm
	1 ½" - 1 ¾"
L	25 - 30 cm
	10" - 1'

Instead of Burn Cut, cross drilling may be used to establish the free surface for wall case.

Mass Concrete

	Concrete	Reinforced Concrete
d	38 - 51 mm	38 - 44 mm
d	1 ½" - 2"	1 ½" - 1 ¾"
L	50 - 90 cm	40 - 60 cm
L	1'8" - 3'	1'4" - 2'

Pile Foundation

d	38 - 44 mm
	1 ½"-1 ¾"
L₁	20 cm
	8"
L₂	20 - 25 cm
	8" - 10"

Thick Wall

d	38 - 44 mm
	1 ½" - 1 ¾"
L	30 - 60 cm
	1' - 2'

Cracks propagate along wall face

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

Pier / Bridge / Foundation

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

(1) Making of large block; Secondary breaking with large rock breaker

(2) Making of small pieces; Drilling is only from one side.

(3) Wall is very high; Vertical drilling is difficult

(4) Foundation is thick, Secondary breaking with large rock breaker.

Zone Demolition

(1) STAGGERED ARRANGEMENT (PILLAR)
d	38 - 44 mm
d	1 ½" - 1 ¾"
L	30 - 40 cm
L	1' - 1'4"
D	90% of Width or Height

(2) X FIGURE ARRANGEMENT (PILLAR, WALL)
d	38 - 44 mm
d	1 ½" - 1 ¾"
L	30 - 40 cm
L	1' - 1'4"
D	90% of Width or Height

(3) CROSS DRILLING (BEAM)
d	38 - 44 mm
d	1 ½" - 1 ¾"
L	30 - 40 cm
L	1' - 1'4"
D	90% of Width or Height

Delayed Filling

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

FIGURE 1: SPLITTING OF LARGE BOULDER
d	32 - 35 mm	44 - 51 mm
d	1 ¼" - 1 3/8"	1 ¾" - 2"
L	30 - 40 cm	60 - 90 cm
L	1' - 1'4"	2' - 3'
D	70% of Height

FIGURE 2: TRENCHING AND TUNNELING OF ROCK
d	38 - 51 mm
d	1 ½" - 2"
L	30 - 60 cm
L	1' - 2'
D	1 - 1.8 m
D	3' - 6'
⊖	45°-60°

Reliever holes are necessary when trench is deep

Repeat the same procedure for deeper case

FIGURE 3: MASS CONCRETE
	Concrete	Reinforced Concrete
d	38 - 51 mm	38 - 44 mm
d	1 ½" - 2"	1 ½" - 1 ¾"
L	50 - 90 cm	40 - 60 cm
L	1'8" - 3'	1'4" - 2'