Does a Sri lankan Passport holder need visa for 18 hour layover at Shanghai (PVG) ?

Hello,
I'm planning to travel from USA to Sri lanka via Shanghai(PVG) terminal 1 , which has a 18 hour layover at Shanghai airport. I'm planning on staying in the airport premises ( terminal 1 , as departing flight to CMB is also from the same terminal). I want to find if I can transit without a visa or if one is needed how to obtain it. It would be great if you could direct me to a chinese government site with this transit withoutvisa descriptions for a sri lankan pasport holder.
Thank you .