Read MoreHong Kong police remove some barricades, say protesters can stay
Students reinforced barricades late on Monday, erecting bamboo scaffolding four meters high along one major thoroughfare, while others mixed concrete to pour over the foundations of their road blocks.
The protesters, mostly students, are demanding full democracy for the former British colony. The protest initially gained wide public support but that has waned as frustrations build over traffic gridlocks gripping the Asian financial hub.
On Tuesday, police cleared some barricades from the bustling shopping district of Causeway Bays as protesters remained largely calm, according to a Reuters witness.
Read MoreHong Kong's leader warns protesters as tent city sprouts up
At the main protest site in Admiralty, next to government buildings and the business district, scores of police stood guard surrounded by hundreds of students, some still sleeping.
Taxi and truck drivers were among those who tried to dismantle barricades on Monday afternoon and some have threatened to return if the protesters do not quit by Wednesday.
The protesters have called on the city's embattled leader, Leung Chun-ying, to step down after Beijing in August ruled out free elections for Hong Kong's next leader in 2017.
Read MoreBad idea, Beijing: Crackdown may kill golden goose
China rules Hong Kong under a "one country, two systems" formula that accords the former British colony a degree of autonomy and freedoms not enjoyed in mainland China, with universal suffrage set as an eventual goal.
Leung has vowed to remain in office and warned that there was "zero chance" that China's leaders in Beijing would change an August decision limiting democracy in Hong Kong.