Investigating the effects of maximum aggregate size on self-compacting steel fiber reinforced concrete fracture parameters

This research has studied the effects of maximum aggregate size of coarse aggregate and volume fraction of steel fibers on the parameters of self-compacting concrete fracture/brittleness. The laboratory program was implemented and the percent fiber and aggregate size were considered variable. Accordingly, 9 mix designs were prepared in 3 series based on 0.1, 0.3, and 0.5% steel fiber and three aggregate sizes (9.5, 12.5, and 19 mm) were considered in each fiber series. A total of 108 different-size notched beams were then prepared and fracture parameters were studied using Work Fracture Method (WFM) and Size Effect Method (SEM). Results have shown that in both methods, the largest aggregate size of 12.5 mm can be appropriate for self-compacting steel fiber-reinforced concrete(SCSFRC), although it is more significant in work fracture method. With the increase of aggregate size to 19 mm, GF and Lch decrease in work fracture method. However, in size effect method the concrete will be more ductile if Vf is increased, and it will be more brittle if dmax is increased. Comparing to the size effect method, the work fracture method performed better in energy absorption with the increase of both aggregate size and the steel fiber percentage. Size effect in such concrete with different fiber percentages was as anticipated and GF/Gf ratio was found 8.89.