What does "Chão de Giz" mean, as sung by Brazilian singer Ze Ramalho?

Google translate gives its meaning as 'ground of chalk' in Portuguese.

http://www.bing.com/search?q=translate+google&src=IE-SearchBox&FORM=IENTSR&pc=EUPP_

In the context of the song the opening verse "I get down from this loneliness spreading things on a chalk floor" seems to indicate a metaphorical floor upon which chalk patterns have perhaps been drawn and will remain there for not much longer since what the chalk stands for (as the whole of the song) is how the love affair was, how the singer feels used and how it all meant so much to him but lasted for such a short time and meant nothing to the other part (and even he is now leaving it all behind). As erasable and or /impermanent as chalk on the ground, really. That's my take on it. Literal translations of course can be Floor made of/covered in chalk.