Experimental Results and Discussion

Uniaxial Tensile Strength Result

The result of the tensile test for the three specimens tested is presented in Fig. 7. The result shows the stress (r) versus CMOD (w) relationship. The result shows an average ultimate tensile strength of 2.90 MPa while the average residual tensile strength at the point of full activation of the fibres is 0.78 MPa at a crack width of about 0.6 mm. Significant crack opening is observed as soon as the specimens cracked (brittle failure with loud noise) at the ultimate tensile strength. This significant crack opening before the fibres were engaged to control further opening is due to the lack of adequate stiffness from the testing machine. For such tests, a test

Fig. 7 Stress-crack opening of tensile test [8]

setup with high stiffness and a servo-controlled closed loop control is more appropriate and will give better results. Secondly, due to the plastic nature of macro-synthetic fibre, some level of stretch is expected before fully being engaged to control crack widening. However, for the purpose of this study, the average residual tensile strength is what is of interest. The creep loads were then based on the average residual strength of 0.78 MPa as depicted in Table 3.

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