Police used teargas against protesting Nehawu members outside the University of Pretoria on Friday morning.
The workers were demanding a 13th cheque, better medical aid, and an 8% increase.
Protesters tried to get onto the university grounds at an open gate on Lynnwood Road after the main gate was closed.
Police fired two canisters of teargas at the protesters, who responded by throwing stones and bricks at the police, before being calmed down by Nehawu leadership.
Regional branch chairperson for Nehawu Joseph Makhasa said other universities not only paid their employees more, but that they also provided a 13th cheque.
Makhasa said if their demands were not met, they intended on disrupting the university's open day, to be held this Saturday.
Nehawu members continued singing and dancing outside the university's main gate in Lynnwood Road.