From article/story of the 1st link(myfoxdfw):
According to Kim Leach of the Dallas County Sheriff's Office, the driver of the concrete truck said while he was headed westbound, his truck was rear-ended by the rock hauler and they both went out of control. However, there was a dispute between the drivers about exactly what happened.
From Comments of the 2nd link(wfaa):
heartlandtx said on November 12, 2010 at 10:38 AM
Seriously, an 18 wheeler says he was hit from behind and pushed into the cement truck? What size car can actually move an 18 wheeler that far and that hard? Really???