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

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

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.