The university had expected students back in class on Wednesday following several days of violent strike action, TUT spokeswoman Willa de Ruyter said.
"They were meant to return but violent protests erupted again at Pretoria and Soshanguve, the arts and Arcadia campuses," she said.
"We decided to close the Pretoria campus for today [Wednesday]."
Students blocked the gates to the campuses, she said.
Police had been called in and security had been increased on the campuses.
"Students have been returning to their lectures. We are monitoring the situation at all our campuses."
Student Representative Council (SRC) secretary general Signified Tivana said on Tuesday students would not return as management had not yet resolved their issues.
"There won't be any classes tomorrow. It is a lie from a pit of hell that students will return to class," he said.
"Whoever comes to the campus will be there to join the strike."
"Students will only go back to classes once the management addresses the students' concerns and readmits SRC members that were suspended," Tivana said.
TUT announced on Monday that it had served the SRC with suspension letters on Sunday.
Source : Sapa