The (elastic brittle) beams had zero residual strength following the initial crack and the DT 20 – and DT 10 B (elastic plastic) beams displayed strain softening following the initial cracking of the – concrete. The DT 10.A beams displayed strain hardening characteristics following the initial crack as displayed in Figure 8. The DT 20 beams showed signs of strain softening immediately after the initial cracking of the concrete, then the dove tailed fibre effect can be seen which was indicated by a rise in the load transfer for an average extension of 0.3mm, thereafter acting as a non linear hinge. The fibres gradually de-bonded and failure, by pull out, was observed in the tension zone below the neutral axis. Figure 8 Load deflection performance – 4.3 Toughness The CMODj values are units of flexural strength given as N/mm2. To achieve a satisfactory performance in accordance with BS 14651, CMOD 1 must be either 1.5 N/mm2 or above and CMOD 4 must achieve a minimum value of 1 N/mm2. All of the fibre concrete results exceed the minimum values laid down in the BS for fibre concrete as displayed in Table 4. Table 4 CMOD data – Flexural Flexural Flexural Flexural Fibres strength at strength at strength at strength at spanning CMOD 1 (CMOD CMOD 2 CMOD 3 CMOD 4 rupture Beam ref 0.5mm) (CMOD 1.5mm) (CMOD 2.5mm) (CMOD 3.5mm) plane 0 P1f 0 0 0 0 0 P2f 0 0 0 0 0 P3f 0 0 0 0 0 P4f 0 0 0 0 0 P5f 0 0 0 0 0 P6f 0 0 0 0 Mean 2.57 2.61 2.48 2.34 39 DT 20.1F 4.38 4.19 4.00 3.78 55 DT 20.2f 4.10 3.81 3.17 2.95 52 DT 20.3f 5.94 5.93 5.77 5.54 74 DT 20.4f 4.47 4.34 4.10 3.84 46 DT 20.5f 3.69 3.67 3.64 3.33 48 DT 20.6f 4.19 4.09 3.86 3.63 52 Mean
The (elastic – brittle) beams had zero residual strength following the initial crack and the DT 20 and DT 10 B (elastic – plastic) beams displayed strain softening following the initial cracking of the concrete. The DT 10.A beams displayed strain hardening characteristics following the initial crack as displayed in Figure 8. The DT 20 beams showed signs of strain softening immediately after the initial cracking of the concrete, then the dove tailed fibre effect can be seen which was indicated by a rise in the load transfer for an average extension of 0.3mm, thereafter acting as a non linear hinge. The fibres gradually de-bonded and failure, by pull out, was observed in the tension zone below the neutral axis. Figure 8 – Load deflection performance 4.3 Toughness The CMODj values are units of flexural strength given as N/mm2. To achieve a satisfactory performance in accordance with BS 14651, CMOD 1 must be either 1.5 N/mm2 or above and CMOD 4 must achieve a minimum value of 1 N/mm2. All of the fibre concrete results exceed the minimum values laid down in the BS for fibre concrete as displayed in Table 4. Table 4 – CMOD data Beam ref Flexural strength at CMOD 1 (CMOD 0.5mm) Flexural strength at CMOD 2 (CMOD 1.5mm) Flexural strength at CMOD 3 (CMOD 2.5mm) Flexural strength at CMOD 4 (CMOD 3.5mm) Fibres spanning rupture plane P1f 0 0 0 0 0 P2f 0 0 0 0 0 P3f 0 0 0 0 0 P4f 0 0 0 0 0 P5f 0 0 0 0 0 P6f 0 0 0 0 0 Mean DT 20.1F 2.57 2.61 2.48 2.34 39 DT 20.2f 4.38 4.19 4.00 3.78 55 DT 20.3f 4.10 3.81 3.17 2.95 52 DT 20.4f 5.94 5.93 5.77 5.54 74 DT 20.5f 4.47 4.34 4.10 3.84 46 DT 20.6f 3.69 3.67 3.64 3.33 48 Mean 4.19 4.09 3.86 3.63 52
Research_methodology_and_results_2.docx