Issue 59

M. A. R. Elmahdy et alii, Frattura ed Integrità Strutturale, 59 (2022) 486-513; DOI: 10.3221/IGF-ESIS.59.32

Figure 32: EDS spectra of mixes (A) M0, (B) M12, (C) M13, (D) M8 and (E) M6.

Mix M0

M12

M13

M8

M6

Atomic %

Weight % 12.46 48.93

Atomic %

Weight % 13.78

Atomic %

Weight %

Atomic %

Weight % 16.68

Atomic %

Element Weight %

C K O K Al K Si K Ca K

11.24 37.26 0.57 4.63 24.46

21.81 54.26 0.49 3.84 14.22

20.52

20.94

16.5

24.51

25.19 56.21 0.45 11.02 5.78

60.48 54.93 62.65 51.99 57.98

49.6 0.72 17.07 12.77

0.77 10.15 20.21

0.56 7.15 9.97

0.77 10.24 20.28

0.52 6.65 9.24

0.78 17.44 13.29

0.51 11.08 5.92

Table 12: Elemental composition of the control and bacterial mortar mixes from EDS analysis.

T HERMO GRAVIMETRIC ANALYSIS (TGA) AND DIFFERENTIAL THERMAL ANALYSIS (DTG) hermo gravimetric analysis (TGA) was performed in order to assume chemically the degree of hydration of various mixtures, which was estimated by the difference in mass between 25 and 1000 °C. The mass loss values have been obtained from the classical experiment (TGA) performed on cement pastes and then Hydration degree assessment of cement pastes was calculated [41]. Cement pastes’ hydration degree calculated is presented in Fig.33. It can be noticed that the short-term hydration degree of mix M6 cement paste was rapidly increasing more than other mixes. The degree of hydration was found to be respectively 35.18, 37.48 and 39.64% at 28, 56 and 90 days. In bacterial pastes, the results showed that the addition of bacteria significantly increased the hydration kinetics, particularly at 56 and 90 days. For instance, the addition of 2.5% of BM bacteria compared with control paste, increased the degree of hydration by respectively 14.96%, 16.39% and 16.62% for 28, 56 and 90 days. Similarly, the use of 2.5% of FP bacteria increased the degree of hydration by respectively 5.39%, 6.37% and 5.12% for 28, 56 and 90 days. This results from the fact that the degree of hydration is increased with an increase in calcite. The DTG thermograms of control and bacterial mortar specimens are shown in Figs.. 34:38. T

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