Crack Width Related to Joint Movement and Crack Length

The nature of the degree of crack opening is illustrated in Fig. 10 and a repre­sentative photograph of the different crack lengths when not extended, and

TABLE 6—Test matrix for water penetration tests on vertical joints.

Crack

Length

(mm)

Joint

Displacement

(mm)

Quantity of Water L/ (min-m2)

1.6

3.4

4

6

No crack (0)

0

0.5

1

2

6a

2

0

0.5

1

2

6a

1b

6a

6a

4

0

0.5

1

2

1b

6a

8

0

0.5

1

2

1b

6a

16

0

0.5

1

2

6a

1b

6a

6a

aSix tests at: 0, 75, 150, 500, 1000, 2000 Pa. bOne test at: 150 Pa.

TABLE 7—Test matrix for water penetration tests on horizontal joints.

Crack

Length

(mm)

Д-Joint

Displacement

(mm)

Quantity of Water L/min

0.088

0.187

0.22

0.33

2

1

2

6a

6a

4

0

0.5

6a

6a

6a

6a

8

0

0.5

1

2

6c

1b

6a

16

0

0.5

1

2

6a

aSix tests at: 0, 75, 150, 500, 1000, 2000 Pa.

bOne test at: 150 Pa.

cSix tests only at Д of 1 mm.

when extended by 0.5, 1, and 2 mm is given in Fig. 11. As is evident from the photograph, the greater the degree of joint extension, the more apparent the crack opening size. This is more evident in the case of the 16 mm and longest crack length shown in Fig. 11 (displacement 2 mm; joint width 22 mm).

The results obtained from joint movement at prescribed displacements and the relation to crack width and crack length is shown in Fig. 12. There is a linear relationship between joint displacement and crack opening (width) for the largest crack length. For shorter crack lengths, this relationship approaches linearity. As well, when the joint is displaced, the longer crack lengths provide for a broader crack opening. Hence, as might be expected, the largest crack openings occur for 16 mm crack lengths at a joint displacement of 2 mm (10 % joint width).