Steel Fiber

The mix design of steel fiber reinforced concrete or SFRC is the same as the mix design of conventional concrete; with the difference that in order to achieve proper efficiency and maximum use of steel fibers, the proportions must be changed. This problem may be satisfied by changing the maximum aggregate size, changing the percentage of cement or adding fly ash. According to the relationships presented in ACI 544.4R-2, the design process of steel fiber reinforced concrete or SFRC can be categorized as follows: the flexural strength of normal concrete behavior is calculated until the first crack; But in concretes reinforced with steel fibers or SFRC concrete, the strength of concrete increases slightly compared to its resistance at the first crack; Therefore: f_d=f_ct (1 R_(e,3)/100) f_d=f_ct f_(e,3) in these relationships: f_d=flexural capacity f_ct=initial cracking resistance f_(e,3)=P_(e, 3)*L/(bh^2 ) R_(e,3)=f_(e,3)/f_ct *100 h,b= depth and width of the section. P_(e,3)=L/150 is the average amount of load that changes the shape of the beam to the amount of compressive strength observed experimentally. By adding steel fibers to concrete, its compressive strength is increased as follows. F_f=F_c (1 K_1 P)=F_c*α which in the above relation: F_f= compressive strength of concrete reinforced with steel fibers F_c= compressive strength of concrete without fibers K_1= experimental constant 0.123 P= volumetric percentage of steel fibers α= coefficient magnification