PROMISSORY NOTE

Exhibit 10.23

PROMISSORY NOTE

PROMISE TO PAY . READY MIX, INC., a Nevada corporation (“Borrower”) promises to pay to NATIONAL BANK OF ARIZONA, a national banking association (“Lender”), or order, in lawful money of the United States of America, the principal amount of One Million Five Hundred Thousand & 00/100 Dollars ($1,500,000.00), together with interest at the rate of 7.345% per annum on the unpaid principal balance from May 26, 2006, until paid in full. The interest rate may change under the terms and conditions of the “INTEREST AFTER DEFAULT” section.

PAYMENT . Borrower will pay this loan in 180 payments of $13,866.95 each payment. Borrower’s first payment is due June 26, 2006, and all subsequent payments are due on the same day of each month after that. Borrower’s final payment will be due on May 26, 2021, and will be for all principal and all accrued interest not yet paid. Payments include principal and interest. Unless otherwise agreed or required by applicable law, payments will be applied first to any accrued unpaid interest; then to principal; then to any unpaid collection costs; and then to any late charges. The annual interest rate for this Note is computed on a 365/360 basis; that is, by applying the ratio of the annual interest rate over a year of 360 days, multiplied by the outstanding principal balance, multiplied by the actual number of days the principal balance is outstanding. Borrower will pay Lender at Lender’s address shown above or at such other place as Lender may designate in writing.

EFFECTIVE RATE. Borrower agrees to an effective rate of interest that is the rate specified in this Note plus any additional rate resulting from any other charges in the nature of interest paid or to be paid in connection with this Note.

PREPAYMENT PENALTY; MINIMUM INTEREST CHARGE. Borrower agrees that all loan fees and other prepaid finance charges are earned fully as of the date of the loan and will not be subject to refund upon early payment (whether voluntary or as a result of default), except as otherwise required by law. In any event, even upon full prepayment of this Note, Borrower understands that Lender is entitled to a minimum interest charge of $250.00. Upon prepayment of this Note, Lender is entitled to the following prepayment penalty: “Prepayment” shall be defined as any accumulated unscheduled principal reduction of more than 5% of the original principal note amount, occurring annually from the anniversary date of this Note. If Borrower chooses to prepay this Note at any time during the first five years, in whole or in part; a prepayment penalty will be due concurrent with the prepayment equal to 5% of the prepayment during the first year, 4% during the second year, 3% during the third year, 2% during the fourth year and 1% during the fifth year. Thereafter, the Borrower may prepay this Note, in whole or in part, without prepayment penalty. Partial prepayments shall then be applied against required payments of the most remote maturity, and will not extend the dates nor change the amounts of subsequent installment payments. No partial prepayment may be made with funds provided through borrowings. Other than Borrower’s obligation to pay any minimum interest charge and prepayment penalty, Borrower may pay all or a portion of the amount owed earlier than it is due. Early payments will not, unless agreed to by Lender in writing, relieve Borrower of Borrower’s obligation to continue to make payments under the payment schedule. Rather, early payments will reduce the principal balance due and may result in Borrower’s making fewer payments. Borrower agrees not to send Lender payments marked “paid in full”, “without recourse”, or similar language. If Borrower sends such a payment, Lender may accept it without losing any of Lender’s rights under this Note, and Borrower will remain obligated to pay any further amount owed to Lender. All written communications concerning disputed amounts, including any check or other payment instrument that indicates that the payment constitutes “payment in full” of the amount owed or that is tendered with other conditions or limitations or as full satisfaction of a disputed amount must be mailed or delivered to: NATIONAL BANK OF ARIZONA, a national banking association; Mesa Main Office; 1119 WEST SOUTHERN AVENUE; MESA, AZ 85210.

LATE CHARGE. If a payment is 10 days or more late, Borrower will be charged 10.000% of the regularly scheduled payment.

INTEREST AFTER DEFAULT. Upon default, including failure to pay upon final maturity, the interest rate on this Note shall be increased to 18.000% per annum. However, in no event will the interest rate exceed the maximum interest rate limitations under applicable law.

DEFAULT. Each of the following shall constitute an event of default (“Event of Default”) under this Note:

Payment Default. Borrower fails to make any payment when due under this Note.

Other Defaults. Borrower fails to comply with or to perform any other term, obligation, covenant or condition contained in this Note or in any of the related documents or to comply with or to perform any term, obligation, covenant or condition contained in any other agreement between Lender and Borrower.

Default in Favor of Third Parties. Borrower or any Grantor defaults under any loan, extension of credit, security agreement, purchase or sales agreement, or any other agreement, in favor of any other creditor or person that may materially affect any of Borrower’s property or Borrower’s ability to repay this Note or perform Borrower’s obligations under this Note or any of the related documents.

Environmental Default. Failure of any party to comply with or perform when due any term, obligation, covenant or condition contained in any environmental agreement executed in connection with any loan.

False Statements. Any warranty, representation or statement made or furnished to Lender by Borrower or on Borrower’s behalf under this Note or the related documents is false or misleading in any material respect, either now or at the time made or furnished or becomes false or misleading at any time thereafter.

Insolvency. The dissolution or termination of Borrower’s existence as a going business, the insolvency of Borrower, the appointment of a receiver for any part of Borrower’s property, any assignment for the benefit of creditors, any type of creditor workout, or the commencement of any proceeding under any bankruptcy or insolvency laws by or against Borrower.

Creditor or Forfeiture Proceedings. Commencement of foreclosure or forfeiture proceedings, whether by judicial proceeding, self-help, repossession or any other method, by any creditor of Borrower or by any governmental agency against any collateral securing the loan. This includes a garnishment of any of Borrower’s accounts, including deposit accounts, with Lender. However, this Event of Default shall not apply if there is a good faith dispute by Borrower as to the validity or reasonableness of the claim which is the basis of the creditor or forfeiture proceeding and if Borrower gives Lender written notice of the creditor or forfeiture proceeding and deposits with Lender monies or a surety bond for the creditor or forfeiture proceeding, in an amount determined by Lender, in its sole discretion, as being an adequate reserve or bond for the dispute.

Events Affecting Guarantor. Any of the preceding events occurs with respect to any guarantor, endorser, surety, or accommodation party of any of the indebtedness or any guarantor, endorser, surety, or accommodation party dies or becomes incompetent, or revokes or disputes the validity of, or liability under, any guaranty of the indebtedness evidenced by this Note. In the event of a death, Lender, at its option, may, but shall not be required to, permit the guarantor’s estate to assume unconditionally the obligations arising under the guaranty in a manner satisfactory to Lender, and, in doing so, cure any Event of Default.

Change In Ownership. Any change in ownership of twenty-five percent (25%) or more of the common stock of Borrower.

Adverse Change. A material adverse change occurs in Borrower’s financial condition, or Lender believes the prospect of payment or performance of this Note is impaired.

Insecurity. Lender in good faith believes itself insecure.

Cure Provisions. If any default, other than a default in payment is curable and if Borrower has not been given a notice of a breach of the same provision of this Note within the preceding twelve (12) months, it may be cured if Borrower, after receiving written notice from Lender demanding cure of such default: (1) cures the default within fifteen (15) days; or (2) if the cure requires more than fifteen (15) days, immediately initiates steps which Lender deems in Lender’s sole discretion to be sufficient to cure the default and thereafter continues and completes all reasonable and necessary steps sufficient to produce compliance as soon as reasonably practical.

LENDER’S RIGHTS. Upon default, Lender may declare the entire unpaid principal balance under this Note and all accrued unpaid interest immediately due, and then Borrower will pay that amount.

ATTORNEYS’ FEES; EXPENSES. Lender may hire or pay someone else to help collect this Note if Borrower does not pay. Borrower will pay Lender that amount. This includes, subject to any limits under applicable law. Lender’s attorneys’ fees and Lender’s legal expenses, whether or not there is a lawsuit, including attorneys’ fees, expenses for bankruptcy proceedings (including efforts to modify or vacate any automatic stay or injunction), and appeals. However, Borrower will only pay attorneys’ fees of an attorney not Lender’s salaried employee, to whom the matter is referred after Borrower’s default. If not prohibited by applicable law, Borrower also will pay any court costs, in addition to all other sums provided by law.

GOVERNING LAW. This Note will be governed by federal law applicable to Lender and, to the extent not preempted by federal law, the laws of the State of Arizona without regard to its conflicts of law provisions. This Note has been accepted by Lender in the State of Arizona.

DISHONORED ITEM FEE. Borrower will pay a fee to Lender of $28.00 if Borrower makes a payment on Borrower’s loan and the check or preauthorized charge with which Borrower pays is later dishonored.

RIGHT OF SETOFF. To the extent permitted by applicable law, Lender reserves a right of setoff in all Borrower’s accounts with Lender (whether checking, savings, or some other account). This includes all accounts Borrower holds jointly with someone else and all accounts Borrower may open in the future. However, this does not include any IRA or Keogh accounts, or any trust accounts for which setoff would be prohibited by law. Borrower authorizes Lender, to the extent permitted by applicable law, to charge or setoff all sums owing on the indebtedness against any and all such accounts.

COLLATERAL. Borrower acknowledges this Note is secured by a Deed of Trust and Fixture Filing, and an Assignment of Rents from Borrower to Lender of even date.

ARBITRATION DISCLOSURES.

(a) Any claim or controversy (“Dispute”) between or among the parties and their employees, agents, affiliates, and assigns, including, but not limited to, Disputes arising out of or relating to this agreement, this arbitration provision (“arbitration clause”),-or any related agreements or instruments relating hereto or delivered in connection herewith (“Related Agreements”), and including, but not limited to, a Dispute based on or arising from an alleged tort, shall at the request of any party be resolved by binding arbitration in accordance with the applicable arbitration rules of the American Arbitration Association (the “Administrator”). The provisions of this arbitration clause shall survive any termination, amendment, or expiration of this agreement or Related Agreements. The provisions of this arbitration clause shall supersede any prior arbitration agreement between or among the parties.

(b) The arbitration proceedings shall be conducted in a city mutually agreed by the parties. Absent such an agreement, arbitration will be conducted in Phoenix, Arizona or such other place as may be determined by the Administrator. The Administrator and the arbitrator(s) shall have the authority to the extent practicable to take any action to require the arbitration proceeding to be completed and the arbitrator(s)’ award issued within 150 days of the filing of the Dispute with the Administrator. The arbitrator(s) shall have the authority to impose sanctions on any party that fails to comply with time periods imposed by the Administrator or the arbitrator(s), including the sanction of summarily dismissing any Dispute or defense with prejudice. The arbitrator(s) shall have the authority to resolve any Dispute regarding the terms of this agreement, this arbitration clause, or Related Agreements, including any claim or controversy regarding the arbitrability of any Dispute. All limitations periods applicable to any Dispute or defense, whether by statute or agreement, shall apply to any arbitration proceeding hereunder and the arbitrator(s) shall have the authority to decide whether any Dispute or defense is barred by a limitations period and, if so, to summarily enter an award dismissing any Dispute or defense on that basis. The doctrines of compulsory counterclaim, res judicata, and collateral estoppel shall apply to any arbitration proceeding hereunder so that a party must state as a counterclaim in the arbitration proceeding any claim or controversy which arises out of the transaction or occurrence that is the subject matter of the Dispute. The arbitrator(s) may in the arbitrator(s)’ discretion and at the request of any party: (1) consolidate in a single arbitration proceeding any other claim arising out of the same transaction involving another party to that transaction that is bound by an arbitration clause with Lender, such as borrowers, guarantors, sureties, and owners of collateral; and (2) consolidate or administer multiple arbitration claims or controversies as a class action in accordance with Rule 23 of the Federal Rules of Civil Procedure.

(c) The arbitrator(s) shall be selected in accordance with the rules of the Administrator from panels maintained by the Administrator. A single arbitrator shall have expertise in the subject matter of the Dispute. Where three arbitrators conduct an arbitration proceeding, the Dispute shall be decided by a majority vote of the three arbitrators, at least one of whom must have expertise in the subject matter of the Dispute and at least one of whom must be a practicing attorney. The arbitrator(s) shall award to the prevailing party recovery of all costs and fees (including attorneys’ fees and costs, arbitration administration fees and costs, and arbitrator(s)’ fees). The arbitrator(s), either during the pendency of the arbitration proceeding or as part of the arbitration award, also may grant provisional or ancillary remedies including but not limited to an award of injunctive relief, foreclosure, sequestration, attachment, replevin, garnishment, or the appointment of a receiver.

(d) Judgement upon an arbitration award may be entered in any court having jurisdiction, subject to the following limitation: the arbitration award is binding upon the parties only if the amount does not exceed Four Million Dollars ($4,000,000.00); if the award exceeds that limit, either party may demand the right to a court trial. Such a demand must be filed with the Administrator within thirty (30) days following the

date of the arbitration award; if such a demand is not made with that time period, the amount of the arbitration award shall be binding. The computation of the total amount of an arbitration award shall include amounts awarded for attorneys’ fees and costs, arbitration administration fees and costs, and arbitrator(s)’ fees.

(e) No provision of this arbitration clause, nor the exercise of any rights hereunder, shall limit the right of any party to: (1) judicially or non-judicially foreclose against any real or personal property collateral or other security; (2) exercise self-help remedies, including but not limited to repossession and setoff rights; or (3) obtain from a court having jurisdiction thereover any provisional or ancillary remedies including but not limited to injunctive relief, foreclosure, sequestration, attachment, replevin, garnishment, or the appointment of a receiver. Such rights can be exercised at any time, before or after initiation of an arbitration proceeding, except to the extent such action is contrary to the arbitration award. The exercise of such rights shall not constitute a waiver of the right to submit any Dispute to arbitration, and any claim or controversy related to the exercise of such rights shall be a Dispute to be resolved under the provisions of this arbitration clause. Any party may initiate arbitration with the Administrator. If any party desires to arbitrate a Dispute asserted against such party in a complaint, counterclaim, cross-claim, or third-party complaint thereto, or in an answer or other reply to any such pleading, such party must make an appropriate motion to the trial court seeking to compel arbitration, which motion must be filed with the court within 45 days of service of the pleading, or amendment thereto, setting forth such Dispute. If arbitration is compelled after commencement of litigation of a Dispute, the party obtaining an order compelling arbitration shall commence arbitration and pay the Administrator’s filing fees and costs within 45 days of entry of such order. Failure to do so shall constitute an agreement to proceed with litigation and waiver of the right to arbitrate. In any arbitration commenced by a consumer regarding a consumer Dispute, Lender shall pay one half of the Administrator’s filing fee, up to $250.

(f) Notwithstanding the applicability of any other law to this agreement, the arbitration clause, or Related Agreements between or among the parties, the Federal Arbitration Act, 9 U.S.C. Section 1 et seq., shall apply to the construction and interpretation of this arbitration clause. If any provision of this arbitration clause should be determined to be unenforceable, all other provisions of this arbitration clause shall remain in full force and effect.

SUCCESSOR INTERESTS. The terms of this Note shall be binding upon Borrower, and upon Borrower’s heirs, personal representatives, successors and assigns, and shall inure to the benefit of Lender and its successors and assigns.

GENERAL PROVISIONS. If any part of this Note cannot be enforced, this fact will not affect the rest of the Note. Lender may delay or forgo enforcing any of its rights or remedies under this Note without losing them. Borrower and any other person who signs, guarantees or endorses this Note, to the extent allowed by law, waive presentment, demand for payment, and notice of dishonor. Upon any change in the terms of this Note, and unless otherwise expressly stated in writing, no party who signs this Note, whether as maker, guarantor, .accommodation maker or endorser, shall be released from liability. All such parties agree that Lender may renew or extend (repeatedly and for any length of time) this loan or release any party or guarantor or collateral; or impair, fail to realize upon or perfect Lender’s security interest in the collateral; and take any other action deemed necessary by Lender without the consent of or notice to anyone. All such parties also agree that Lender may modify this loan without the consent of or notice to anyone other than the party with whom the modification is made. The obligations under this Note are joint and several.

PRIOR TO SIGNING THIS NOTE, BORROWER READ AND UNDERSTOOD ALL THE PROVISIONS OF THIS NOTE. BORROWER AGREES TO THE TERMS OF THE NOTE.

BORROWER ACKNOWLEDGES RECEIPT OF A COMPLETED COPY OF THIS PROMISSORY NOTE.

BORROWER:

READY MIX, INC., A NEVADA CORPORATION

By: /s/ Bradley E. Larson                                   
        BRADLEY E. LARSON, Chief Executive Officer of
       READY MIX, INC., a Nevada corporation

LASER PRO Lending, Ver. 5.31.00.004 Copr. Harland Financial Solutions, Inc. 1997, 2006. All Rights Reserved. — AZ C:\LPWIN\CFI\LPL\D20.FC TR-26474 PR-1

BUSINESS LOAN AGREEMENT

THIS BUSINESS LOAN AGREEMENT dated May 26, 2006, is made and executed between READY MIX, INC., a Nevada corporation (“Borrower”) and NATIONAL BANK OF ARIZONA, a national banking association (“Lender”) on the following terms and conditions. Borrower has received prior commercial loans from Lender or has applied to Lender for a commercial loan or loans or other financial accommodations, including those which may be described on any exhibit or schedule attached to this Agreement (“Loan”). Borrower understands and agrees that: (A) in granting, renewing, or extending any Loan, Lender is relying upon Borrower’s representations, warranties, and agreements as set forth in this Agreement; (B) the granting, renewing, or extending of any Loan by Lender at all times shall be subject to Lender’s sole judgment and discretion; and (C) all such Loans shall be and remain subject to the terms and conditions of this Agreement.

TERM. This Agreement shall be effective as of May 26, 2006, and shall continue in full force and effect until such time as all of Borrower’s Loans in favor of Lender have been paid in full, including principal, interest, costs, expenses, attorneys’ fees, and other fees and charges, or until such time as the parties may agree in writing to terminate this Agreement.

CONDITIONS PRECEDENT TO EACH ADVANCE. Lender’s obligation to make the initial Advance and each subsequent Advance under this Agreement shall be subject to the fulfillment to Lender’s satisfaction of all of the conditions set forth in this Agreement and in the Related Documents.

Loan Documents. Borrower shall provide to Lender the following documents for the Loan: (1) the Note; (2) Security Agreements granting to Lender security interests in the Collateral; (3) financing statements and all other documents perfecting Lender’s Security Interests; (4) evidence of insurance as required below; (5) together with all such Related Documents as Lender may require for the Loan; all in form and substance satisfactory to Lender and Lender’s counsel.

Borrower’s Authorization. Borrower shall have provided in form and substance satisfactory to Lender properly certified resolutions, duly authorizing the execution and delivery of this Agreement, the Note and the Related Documents. In addition, Borrower shall have provided such other resolutions, authorizations, documents and instruments as Lender or its counsel, may require.

Payment of Fees and Expenses. Borrower shall have paid to Lender all fees, charges, and other expenses which are then due and payable as specified in this Agreement or any Related Document.

Representations and Warranties. The representations and warranties set forth in this Agreement, in the Related Documents, and in any document or certificate delivered to Lender under this Agreement are true and correct.

No Event of Default. There shall not exist at the time of any Advance a condition which would constitute an Event of Default under this Agreement or under any Related Document.

REPRESENTATIONS AND WARRANTIES. Borrower represents and warrants to Lender, as of the date of this Agreement, as of the date of each disbursement of loan proceeds, as of the date of any renewal, extension or modification of any Loan, and at all times any Indebtedness exists:

Organization. Borrower is a corporation for profit which is, and at all times shall be, duly organized, validly existing, and in good standing under and by virtue of the laws of the State of Nevada. Borrower is duly authorized to transact business in the State of Arizona and all other states in which Borrower is doing business, having obtained all necessary filings, governmental licenses and approvals for each state in which Borrower is doing business. Specifically, Borrower is, and at all times shall be, duly qualified as a foreign corporation in all states in which the failure to so qualify would have a material adverse effect on its business or financial condition. Borrower has the full power and authority to own its properties and to transact the business in which it is presently engaged or presently proposes to engage. Borrower maintains an office at 3430 EAST FLAMINGO ROAD, SUITE 100, LAS VEGAS, NV 89121. Unless Borrower has designated otherwise in writing, the principal office is the office at which Borrower keeps its books and records including its records concerning the Collateral. Borrower will notify Lender prior to any change in the location of Borrower’s state of organization or any change in Borrower’s name. Borrower shall do all things necessary to preserve and to keep in full force and effect its existence, rights and privileges, and shall comply with all regulations, rules, ordinances, statutes, orders and decrees of any governmental or quasi-governmental authority or court applicable to Borrower and Borrower’s business activities.

Assumed Business Names. Borrower has filed or recorded all documents or filings required by law relating to all assumed business names used by Borrower. Excluding the name of Borrower, the following is a complete list of all assumed business names under which Borrower does business: None.

Authorization. Borrower’s execution, delivery, and performance of this Agreement and all the Related Documents have been duly authorized by all necessary action by Borrower and do not conflict with, result in a violation of, or constitute a default under (1) any provision of (a) Borrower’s articles of incorporation or organization, or bylaws, or (b) any agreement or other instrument binding upon Borrower or (2) any law, governmental regulation, court decree, or order applicable to Borrower or to Borrower’s properties.

Financial Information. Each of Borrower’s financial statements supplied to Lender truly and completely disclosed Borrower’s financial condition as of the date of the statement, and there has been no material adverse change in Borrower’s financial condition subsequent to the date of the most recent financial statement supplied to Lender. Borrower has no material contingent obligations except as disclosed in such financial statements.

Legal Effect. This Agreement constitutes, and any instrument or agreement Borrower is required to give under this Agreement when delivered will constitute legal, valid, and binding obligations of Borrower enforceable against Borrower in accordance with their respective terms.

Properties. Except as contemplated by this Agreement or as previously disclosed in Borrower’s financial statements or in writing to Lender and as accepted by Lender, and except for property tax liens for taxes not presently due and payable, Borrower owns and has good title to all of Borrower’s properties free and clear of all Security Interests, and has not executed any security documents or financing statements relating to such properties. All of Borrower’s properties are titled in Borrower’s legal name, and Borrower has not used or filed a financing statement under any other name for at least the last five (5) years.

Hazardous Substances. Except as disclosed to and acknowledged by Lender in writing, Borrower represents and warrants that: (1) During the period of Borrower’s ownership of the Collateral, there has been no use, generation, manufacture, storage, treatment, disposal, release or threatened release of any Hazardous Substance by any person on, under, about or from any of the Collateral. (2) Borrower has no knowledge of, or reason to believe that there has been (a) any breach or violation of any Environmental Laws; (b) any use, generation, manufacture, storage, treatment, disposal, release or threatened release of any Hazardous Substance on, under, about or from the

Collateral by any prior owners or occupants of any of the Collateral; or (c) any actual or threatened litigation or claims of any kind by any person relating to such matters. (3) Neither Borrower nor any tenant, contractor, agent or other authorized user of any of the Collateral shall use, generate, manufacture, store, treat, dispose of or release any Hazardous Substance on, under, about or from any of the Collateral; and any such activity shall be conducted in compliance with all applicable federal, state, and local laws, regulations, and ordinances, including without limitation all Environmental Laws. Borrower authorizes Lender and its agents to enter upon the Collateral to make such inspections and tests as Lender may deem appropriate to determine compliance of the Collateral with this section of the Agreement. Any inspections or tests made by Lender shall be at Borrower’s expense and for Lender’s purposes only and shall not be construed to create any responsibility or liability on the part of Lender to Borrower or to any other person. The representations and warranties contained herein are based on Borrower’s due diligence in investigating the Collateral for hazardous waste and Hazardous Substances. Borrower hereby (1) releases and waives any future claims against Lender for indemnity or contribution in the event Borrower becomes liable for cleanup or other costs under any such laws, and (2) agrees to indemnify and hold