Comparison of the effect of different additives on acoustic emission parameters obtained during three-point bending tests of alkali-activated slag composites

Influence of Graphite Powder on the Mechanical and Acoustic Emission Characteristics of Concrete

“…As a result, the amount of AE activity during loading is significantly reduced by graphite powder, which is consistent with the findings of Ref. [12]. The AE signals around turning point L and K in Figure 14b,c are obviously less active than Figure 14a.…”

“…Afterwards, within only 2.3% of strain, the damage degree increased from 0.61 to 1.0, indicating typical brittle fracture behavior. As shown in Figure 15b,c, due to the initial defects caused by graphite powder [12], although a high damage value of concrete occurs at low strain levels, the strain between turning point O and peak load increases to 10.6% and 31.5%; the deformation is larger in failure, and the D-ε curve has a more linear relationship, so that the damage form is changed from a brittle fracture to ductile fracture, and the failure of concrete under compression is more predictable.…”

“…However, due to its high specific surface area, flake shape, and poor adhesion with cement stone, the mechanical properties and failure pattern of concrete are significantly changed. Topolář et al [12] compared the effect of carbon black and graphite powder on the acoustic emission parameters during three-point bending tests, and it was found that an acoustic emission method was able to detect failure at a very early stage, long before a structure completely fails, and that the acoustic emission characteristics of concrete vary with graphite powder dosage. However, there is a lack of extended research into the early warning time and the trends in damage development at various filler dosages.…”