PSI - Issue 70

R. Karthikeyan et al. / Procedia Structural Integrity 70 (2025) 89–96

90

In an endeavor to amend the performance of concrete, researchers have simultaneously tried substituting waste rubber for aggregates. thin cement paste coating, Styrene Butadiene rubber, as well as natural sulfur varnish [Chou Let.al, 2010] are some of the methods that have been tried to improve the transition zone between two surfaces. The mechanical characteristics of rubberized concrete were considerably enhanced by certain techniques [Najim K.B. and Hall M.R. 2010] Concrete that has steel fibres added to it is more impact and fatigue resistant, ductile, robust, and resistant to post-crack degradation. [Grunewald S et.al, 2001]. Steel fibres are added to uncertain concrete to provide it ductility, which is very important for buildings in seismically active areas. By adding steel fibres to structural concrete, it becomes less brittle, which increases its tensile strength [Corinaldesi and Moriconi al 2004]. FRC gives better ductility when compare to normal concrete. Fibre reinforced concrete has been used for many civil applications such as roads, sleeper’s etc. The hybrid use enhanced the flexural behavior compared to the macro fibre usage. Therefore, an evaluation of the effect of micro-reinforcement on rubberized concrete beam performance has been attempted 2. Materials and Methods 2.1 Materials Concrete had a compressive strength of 26 MPa. The concrete's composition was, fine aggregate (715 kg/m3), coarse aggregate (20 mm) (702 kg/m3) &12.5 (468kg/m3), and Portland cement (380 kg/m3) with a w/c of 0.45. Deformed bars with a yield value of 456 MPa made up the transverse bar. Rubber -cut pieces with a size of 20 mm and a specific gravity of 1.24 that were prepared from conveyer belts were used. Sand coated rubber shreds as shown in Fig.1. The beam specimens were made with different replacement levels of CA (2.5%, 5.0%, and 7.5%) with pretreated rubber shreds and different volume fractions (0.5%, 1.0%) of steel fibres were used. The rubber shreds were sand coated to improve their bonding with cement matrix. Steel fibres having an aspect ratio of 80 and a tensile strength of 1225 MPa were used. Specifics of the Examined Beams is shown in Table1.

Fig.1 Sand coated Rubber shreds

Table 1 Specifics of the Examined Beams

Steel Ratio

Sand coated rubber shreds (%)

Steel Fibre Volume Percentage (%)

SI.No

Identification of Beams

1. 2. 3. 4. 5. 6. 7.

SC

0.603 0.603 0.603 0.603 0.603 0.603 0.603

0

0

SR11 SR12 SR21 SR22 SR31 SR32

2.5 2.5

0.5

1

5 5

0.5

1

7.5 7.5

0.5

1