Materials

Polymer fibres in this paper are anonymized and identified by their length (L) and aspect ratio (L/d), while steel fibres are additionally identified by their anchor type and wire characteristic (Table 1). The 5D fibre distinguishes itself from other fibres by its double hooked end, high tensile strength and additional higher ultimate strain of 6 %.

Three concrete mixes are applied (Table 2); varying in compressive strength, aggregate type and maximum aggregate size. Specimens were cured for at least 28 days under water before the pre-cracking stage to allow for better repetitiveness of results. However panels in programs B2 and B3 were pre-cracked and set up

Table 1 Fibre characteristics

Fiber ID

Material

L

L/d

fu

E

P

Anchor type

(mm)

(-)

(MPa)

(GPa)

(kg/m3)

PF-83/50

Polymer

50

83

620

9.5

920

Embossed

PF-90/40

Polymer

40

90

620

9.5

920

Embossed

PF-48/48

Polymer

48

48

520

10

920

Embossed

PF-73/65

Polymer

65

73

640

10

920

Embossed

PF-80/54

Polymer

54

80

580

4.7

920

Embossed

3D 45/30BG

Steel

30

45

1270

200

7800

3D anchor

3D 65/35BG

Steel

35

65

1345

200

7800

3D anchor

3D 65/60BG

Steel

60

65

1160

200

7800

3D anchor

3D 80/60BG

Steel

60

80

1225

200

7800

3D anchor

5D 65/60BG

Steel

60

65

2300

200

7800

5D anchor

Table 2 Overview of different concrete compositions (dry weights, kg/m3)

Concrete

C1

C2

C3

C35/45

C30/37

C25/30

CEM I 42,5 R HES

427

350

280

River sand 0/4

854

822

822

Broken limestone 4/7

854

456

-

Round gravel 5/15

-

-

1003

Broken limestone 7/14

-

547

-

Water

214

186

168

after only 2 days to simulate conditions related to shotcreting. All specimens are exposed to minimum room temperature of 16 °C. There is no control of air temperature or relative humidity.

 
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