65 ILCS 5/9-2-111

Except as otherwise provided in Section 9-2-113, if the owners or contractors, who may have taken any contract, do not complete the work within the time mentioned in the contract, or within such further time as the board of local improvements may give them, the board may relet the unfinished portions of that work, after pursuing the formalities prescribed hereinbefore for the letting of the whole in the first instance.

All contractors, contracting owners included, at the time of executing any contract for such public work, shall execute a bond to the satisfaction and approval of the board of local improvements of the municipality, in such sum as the board deems adequate, conditioned for the faithful performance of the contract. The sureties shall justify, before some person competent to administer an oath, in double the amount mentioned in that bond, over and above all statutory exemptions.