An absorbent structure comprises an expansion loop core configured to expand in response to absorption of a liquid and an expansion loop material surrounding the expansion loop core. The expansion loop material has a trough therein. The trough is formed from a first portion of the expansion loop material folded over a second portion of the expansion loop material at a first elbow of the expansion loop material. In response to an increase in size of the expansion loop core, the expansion loop core presses against the expansion loop material to cause a length of the trough to decrease.
