For the purpose of paying and securing the payment of the principal of and interest on the bonds as the same shall become due, there shall be paid into the state treasury and credited to the respective bond retirement fund of each university or college issuing bonds, the following:
(1) Amounts derived from building fees as the board shall certify as necessary to prevent default in the payments required to be paid into such bond retirement fund;
(2) Any grants which may be made, or may become available, for the purpose of furthering the construction of any authorized projects, or for the repayment of the costs thereof;
(3) Such additional funds as the legislature may provide.
Said bond retirement fund shall be kept segregated from all moneys in the state treasury and shall, while any of such bonds or any interest thereon remains unpaid, be available solely for the payment thereof. As a part of the contract of sale of such bonds, the board shall undertake to charge and collect building fees and to deposit the portion of such fees in the bond retirement fund in amounts which will be sufficient to pay and secure the payment of the principal of, and interest on all such bonds outstanding.