How sampling aperiodic signal will result in periodic repetitions of the same
sampling guarantees periodicity 


Not exactly. Sampling in one domain guarantees periodicity in the other domain. So sampling in time creates a periodic spectrum and sampling in frequency creates a periodic time signal. Or the other one around: a periodic time signal has a discrete spectrum and a periodic spectrum has a discrete time signal.

That's why there are four different "types" of Fourier Transform. One for each permutations of continuous vs discrete in each domain. See for example http://fourier.eng.hmc.edu/e101/lectures/handout4/node3.html or https://www.dspguide.com/ch8/1.htm