25 Detection and Evaluation of Vascular Network Based …
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FR(i) is the Felicity Ratio of the ith loading during a cyclic loading;
P MAX (i) is the maximum load during the ith loading;
P AE (i + 1) is the loading level when considerable AE resumes at the i + 1th load.
From previous study, combination use of the Kaiser effect and Felicity effect
can be efficiently used to determine whether major structural defects are present.
Furthermore, Felicity Ratio can become an important criterion for evaluating the
severity of material defects. It is complied with Kaiser effect when Felicity Ratio is
greater than 1, or against the Kaiser Effect when Felicity Ratio is less than 1.
25.3.3.2 Determination of Valid Emission Signals
In terms of concrete, because of its complexity and it’s a kind of polyphase and
compound material, can be influenced by many factors. So many different kinds
of defects, cracks and microstructural inhomogeneity are already contained inside
before any load applied. In that case, some microcracks will deform and propagate
even under relatively low stress condition. Therefore, it is of great importance to determine whether there are “effective AE signal” received and corresponding loading
magnitude during the process of cyclic loading. However, up to now there is no agreed
definition about the concept of “effective AE signal”. Normally researchers just
distinguish the signals by using their own experience and properties of corresponding
material.
During the experiments, it was observed that occasionally some cement paste
caused by spalling may peel and the AE amplitude will increase significantly. But
this kind of signal is very short and therefore it cannot be regarded as the valid
AE signal as a sign of AE recovery. Hongguang and Zaoding [5] conducted an
experimental study with respect to the relationship of Kaiser and Felicity effect
in concrete material. According to his findings, the following two criteria can be
considered to use as the determination for “effective AE signal” in concrete:
1. AE signals has been continuously increasing when load increases;
2. More than 10 AE hits are received in the process of increasing the load by 10%.
25.3.3.3 Healing Performance Evaluation
To more intuitively characterize and better quantify the degree of self-healing, another
index HI, called “Healing Index”, is introduced and defined as the following equation.
HI(% ) = 100 · (1 − FR)
(2)
According to these two criteria, the results of Facility Ratio calculated are shown
in Table 25.2.
As shown in Table 25.2, the Felicity Ratio is related to different healing time and
relatively decreases with the increasing strength recovery of healing. This is because
the specimen is internally microcracked and damaged during the first loading, and
309
FR(i) is the Felicity Ratio of the ith loading during a cyclic loading;
P MAX (i) is the maximum load during the ith loading;
P AE (i + 1) is the loading level when considerable AE resumes at the i + 1th load.
From previous study, combination use of the Kaiser effect and Felicity effect
can be efficiently used to determine whether major structural defects are present.
Furthermore, Felicity Ratio can become an important criterion for evaluating the
severity of material defects. It is complied with Kaiser effect when Felicity Ratio is
greater than 1, or against the Kaiser Effect when Felicity Ratio is less than 1.
25.3.3.2 Determination of Valid Emission Signals
In terms of concrete, because of its complexity and it’s a kind of polyphase and
compound material, can be influenced by many factors. So many different kinds
of defects, cracks and microstructural inhomogeneity are already contained inside
before any load applied. In that case, some microcracks will deform and propagate
even under relatively low stress condition. Therefore, it is of great importance to determine whether there are “effective AE signal” received and corresponding loading
magnitude during the process of cyclic loading. However, up to now there is no agreed
definition about the concept of “effective AE signal”. Normally researchers just
distinguish the signals by using their own experience and properties of corresponding
material.
During the experiments, it was observed that occasionally some cement paste
caused by spalling may peel and the AE amplitude will increase significantly. But
this kind of signal is very short and therefore it cannot be regarded as the valid
AE signal as a sign of AE recovery. Hongguang and Zaoding [5] conducted an
experimental study with respect to the relationship of Kaiser and Felicity effect
in concrete material. According to his findings, the following two criteria can be
considered to use as the determination for “effective AE signal” in concrete:
1. AE signals has been continuously increasing when load increases;
2. More than 10 AE hits are received in the process of increasing the load by 10%.
25.3.3.3 Healing Performance Evaluation
To more intuitively characterize and better quantify the degree of self-healing, another
index HI, called “Healing Index”, is introduced and defined as the following equation.
HI(% ) = 100 · (1 − FR)
(2)
According to these two criteria, the results of Facility Ratio calculated are shown
in Table 25.2.
As shown in Table 25.2, the Felicity Ratio is related to different healing time and
relatively decreases with the increasing strength recovery of healing. This is because
the specimen is internally microcracked and damaged during the first loading, and