I did a small amount of digging myself, and it looks like salt trucks and sanitation vehicles were used on Thursday to protect protesters, because earlier this week a car drove through a barricade into a a group of protesters.
From the article linked below ...
As the protesters marched on, traffic was blocked off. Chicago Streets and Sanitation vehicles as well as salt trucks were seen along the route to prevent vehicles from entering. Just two days ago, the driver of a vehicle drove through protesters blocking the 100 block of East Monroe Street, injuring a 66-year-old woman.
https://wgntv.com/news/chicago-news/more-ice-protests-expected-thursday-in-chicago/
Quite a few of the reddit users on the sub where this was posted did research and coud not find any mention or any report about salt trucks blocking ICE/NG, even though they wished it was true.
A couple of excerpts ...
"Seriously, is this reported anywhere? If not mods need to remove it. I cant find one reliable source. Edit: and OP is a 20 day old account that keeps posting Truth Social links as a source. This feels like a disinformation campaign."
"theres no source, only online fan fiction. That would be badass though. Guess thats why gullible folks share it."
"Exactly, and its the same blurry TikTok video being passed around. Whats the chance all these trucks are out and in two days nobody else posts anything."
"Doesnt seem to be true, or at least no confirmation."
"The taste of Chicago is going on at millennium park/grant park rn Im not saying there isnt increased awareness right now but this is also part of typical road blocking and traffic diversion in Chicago for major events especially around grant park and millennium."
etc, etc.