What is the main rhetorical device of "Ain't I a Woman" by Sojourner Truth?

In 1851, a Women's Rights conference was held in Akron. One person attending was Sojourner Truth, an older African American woman who had been emancipated from slavery. At the meeting, several men had spoken against women's rights, suggesting that women were weak and lacking in intellect. They used Biblical arguments such as the fact that Christ was a man and Eve was a woman. 
A number of people did not want Truth to speak because they thought that her speech would associate the women's movement with the abolitionist movement. Nevertheless, she was given the floor. 
The speech she gave is called "Ain't I a Woman," and is called so because of the main rhetorical device Sojourner Truth used, conduplicatio, which is the repetition of a word or phrase. In her speech, she describes things she has done that challenge the idea that women are weak, and after each sentence, she said, "and ain't I a woman?" 
Conduplicatio can be a very powerful device when used wisely in a speech. One hundred and twelve years after Sojourner Truth made her speech, an African American preacher used conduplicatio, which is how we remember his speech: "I have a dream."
https://books.google.com/books?id=16rQl2WT_-gC&pg=PA18

https://sourcebooks.fordham.edu/mod/sojtruth-woman.asp