Issue 59

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

Figure 12: Effect of bacteria concentration on compressive strength results for reloaded cracked specimens and specimens without pre-cracking using 0.25% bacteria BM and 0.5% Ca La: (A) at 28 days, (B) at 56 days, and (C) at 90 days.

Figure 13: Effect of bacteria concentration on compressive strength results for reloaded cracked specimens and specimens without pre-cracking using 0.25% bacteria EMCC and 0.5% Ca La: (A) at 28 days, (B) at 56 days, and (C) at 90 days.

Figure 14: Effect of bacteria concentration on compressive strength results for reloaded cracked specimens and specimens without pre-cracking using 2.5% bacteria BM and 0.5% Ca La: (A) at 28 days, (B) at 56 days, and (C) at 90 days.

Figure 15: Effect of bacteria concentration on compressive strength results for reloaded cracked specimens and specimens without pre-cracking using 2.5% bacteria EMCC and 0.5% Ca La: (A) at 28 days, (B) at 56 days, and (C) at 90 days.

E FFECT OF BACTERIA TYPE

he results showed that using bacteria increased the compressive strength of reloaded cracked specimens so close to the specimens without pre-cracking compared with control mix with a percentage reaching to 82%, 89.2%, and 98.77% of ultimate compressive strength at ages of 28, 56, and 90 days respectively for M6 using bacteria BM. On the other hand, when using bacteria EMCC, the compressive strength of reloaded cracked specimens reaches 78.7%, 86 and 98.72% of ultimate compressive strength at ages of 28, 56 and 90 days, respectively for M8. Also, using bacteria FP, the compressive strength of reloaded cracked specimens reached 66.8%, 78.4% and 85.1% of ultimate compressive strength at ages of 28, 56 and 90 days, respectively for M14. Overall, the increase in compressive strength for reloaded cracked specimens increases with the increase in the age of specimens. The results confirm that the Bacillus megaterium bacteria of the bacillus family was found to be effective in improving mechanical strength by reducing voids [26,33,34,48]. T

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