Experimental investigation into the properties of self-compacting rubberised concrete incorporating polypropylene and steel fibers

Adding a waste tyre rubber aggregate to the self-compacting concrete forms a new type of concrete call self-compacting rubberise concrete, which is used as a way of reducing waste and increasing sustainability in terms of the waste rubber, and changing the properties of the concrete to be more beneficial under certain circumstances and applications. In addition to adding rubber aggregates, polypropylene (PP) fibers and steel fibers are added into the concrete mix as well to create fiber reinforced self-compacting rubberised concrete (FRSCRC). This experimental investigation is using waste tyre rubber as a replacement for the aggregate in the FRSCRC. Using crumb rubber sizes of 2?5 mm, a replacement of 20% of fine aggregates was integrated. The amount of fibers varied depending on the type of fiber. In the case of PP fibers, 0.1, 0.15, 0.2, and 0.25% by total volume were tested, and for steel, 0.25, 0.5, 0.75, and 1% were tested. These mixes were tested for their fresh properties using the slump test and the J-ring test, and hardened properties including compressive strength, splitting tensile strength and compressive stress?strain tests. The results indicated that as more fiber is added, the larger the negative impact on the rheological properties of the FRSCRC and steel fibers having a much larger detrimental effect than PP fibers. In terms of mechanical properties, PP fibers reduced the compressive strength of the concrete as a higher percentage of fiber was added, but had no major effect on the splitting tensile strength. Steel fibers, on the other hand, showed a minor increase to compressive strength, as well as an increase to splitting tensile strength as more fibers were added.