Why are Aardvarks capable of burrowing given their size?
The following paper examines the link between burrowing ability and the stress and strain resistance provided by increased endosteal tissue formation (specifically compacted coarse cancellous bone (CCCB)) in aardvarks:

Physiological constraints associated with digging, however, are known to be strongly influenced by body size, and larger burrowers are likely to exhibit a histological profile more conspicuously influenced by fossorial activity. Here, we describe for the first time the limb bone histology of the aardvark (Orycteropus afer), the largest extant burrowing mammal...
We hypothesize that the unusual histological profile of the aardvark is likely the outcome of physiological constraints due to both extensive digging behavior and strong metabolic restrictions. Adaptations to fossoriality are thus the result of a physiological compromise between limited food availability, an environment with high temperature variability, and the need for biomechanical resistance during digging. These results highlight the difficulties of deciphering all factors potentially involved in bone formation in fossorial mammals. Even though the formation and maintaining of CCCB through ontogeny in the aardvark cannot be unambiguously linked with its fossorial habits, a high amount of CCCB has been observed in the limb bones of other large burrowing mammals.


Digging the compromise: investigating the link between limb bone histology and fossoriality in the aardvark (Orycteropus afer), PeerJ Life &amp; Environment (2018)

Further reading:

Ecosystem engineering through aardvark (Orycteropus afer) burrowing: Mechanisms and effects