5-18A-36. Performance and payment bond or approved security. For any public improvement contract, a performance and payment bond is required pursuant to chapter 5-21. For any other contract, a purchasing agency may require a bond or an approved security to be provided by the successful offeror or bidder as a guarantee of faithful performance of the contract. In any case, the bond or approved security of the successful offeror or bidder shall be returned upon satisfactory completion of the contract.