The Collaborative International Dictionary of English v.0.48:

Bituminate \Bi*tu"mi*nate\ (b[i^]*t[=u]"m[i^]*n[=a]t), v. t.
   [imp. & p. p. Bituminated; p. pr. & vb. n. Bituminating.]
   [L. bituminatus, p. p. of bituminare to bituminate. See
   Bitumen.]
   To treat or impregnate with bitumen; to cement with bitumen.
   "Bituminated walls of Babylon." --Feltham.
   [1913 Webster]