According to my linguistics text by Edward Finegan, a circumfix is a combination of a prefix and suffix, but that wouldn't apply in your situation. But apparently the concept also applies to adjectives.

"We address the two reduplication patterns in Mandarin Chinese where a disyllabic verb in the form of /AB/ is reduplicated as [ABAB] while a disyllabic adjective in the form of /AB/ is reduplicated as [AABB]. Chen 2000 claims that Chinese minimal rhythmic unit (MRU) is structured disyllabically. Both [ABAB] and [AABB] have a prosodic structure of (ss)(ss). Based on the difference between [AABB] and [ABAB] in their tone sandhi behaviors, the morphological structure for [ABAB] is claimed to be the same as its phonological structure. However, the morphological structure for [AABB] is misaligned with its phonological structure. The different
prioritization of LINEARITY with respect to the alignment constraints (ALIGN(Verb, MRU) and ALIGN(Adjective, MRU): Align the edges of the verb/adjective morpheme with the edges of MRU) explains their different reduplication patterns. The higher priority given to LINEARITY in adjective reduplication produces the rarely seen pattern of circumfixing reduplication [A AB B].

http://www.lsadc.org/meethandbook2003.pdf