Issue34

S. Ahmad et alii, Frattura ed Integrità Strutturale, 34 (2015) 524-533; DOI: 10.3221/IGF-ESIS.34.58 529 samples were tested in flexure and the broken pieces were tested for compressive strengths. Typical load-CMOD curves of the cement composite samples are presented in Fig. 5. Figure 5 : Typical load-CMOD curves for cement composites with and without pyrolyzed coconut shells particles. The average modulus of rupture of cement composite samples and their compressive strengths are reported in Figs. 6 and 7 respectively. The results indicates that the flexural strength of the cement composites reduces with the inclusion of the pyrolyzed coconut shells particles, even a small amount of pyrolyzed coconut shell particles (i.e. 0.05%) may reduce the modulus of rupture up to 20% for both types of carbonized and carbonized & annealed coconut shell particles. This reduction may be attributed to the large number of inert inclusions in the composite matrix. In case of compressive strength, all the mixes showed increased strength as compared to the control mix but this increment showed no relation with the amount of inert particles inclusion. Figure 6 : Modulus of rupture of cement composites with PC & PCA particles inclusions. Figure 7 : Compressive strength of the cement composites with PC & PCA particles inclusions. The load-CMOD relations of the cement composite samples showed that the unstable cracks growth initiate around 0.010±0.002 mm CMOD in control mix and around 0.018±0.002 mm for the samples containing various amounts of inert pyrolyzed coconut shells particles. This indicates that the unstable crack growth as well as the final split or the braking of the cement paste composites is delayed by the addition of inert carbonized particles. The enhancement in the maximum CMOD varies from sample to sample, with an average trend of 80% to 100% enhancement. The result of this