
<PAGE>
                         NOTICE OF GUARANTEED DELIVERY
                                      FOR
                        TENDER OF SHARES OF COMMON STOCK
            (INCLUDING THE ASSOCIATED COMMON SHARE PURCHASE RIGHTS)
                                       OF
                                   CALMAT CO.
                                       TO
                          ALB ACQUISITION CORPORATION
                           A WHOLLY OWNED SUBSIDIARY
                                       OF
                            VULCAN MATERIALS COMPANY
                   (NOT TO BE USED FOR SIGNATURE GUARANTEES)
 
     This Notice of Guaranteed Delivery or one substantially equivalent hereto
must be used to accept the Offer (as defined below) if certificates representing
shares of Common Stock, par value $1 per share (the "Shares"), of CalMat Co., a
 Delaware corporation (the "Company"), and the associated Rights (as defined in
 the Offer to Purchase), are not immediately available or time will not permit
  all required documents to reach First Chicago Trust Company of New York (the
  "Depositary") on or prior to the Expiration Date (as defined in the Offer to
   Purchase), or the procedures for delivery by book-entry transfer cannot be
completed on a timely basis. This Notice of Guaranteed Delivery may be delivered
    by hand or sent by mail to the Depositary. See Section 3 of the Offer to
                                   Purchase.
 
                        THE DEPOSITARY FOR THE OFFER IS:
                    FIRST CHICAGO TRUST COMPANY OF NEW YORK
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<S>                                        <C>
                BY MAIL:                                 BY OVERNIGHT DELIVERY:
 First Chicago Trust Company of New York        First Chicago Trust Company of New York
           Tenders & Exchanges                            Tenders & Exchanges
               Suite 4660                    c/o Securities Transfer and Reporting Services
              P.O. Box 2569                                       Inc.
       Jersey City, NJ 07303-2569                   One Exchange Plaza--Third Floor
                                                           New York, NY 10006
 
<CAPTION>
                BY MAIL:                                   BY HAND:
 First Chicago Trust Company of New York    First Chicago Trust Company of New York
           Tenders & Exchanges                        Tenders & Exchanges
               Suite 4660                                 Suite 4680
              P.O. Box 2569                        14 Wall Street, 8th Floor
       Jersey City, NJ 07303-2569                     New York, NY 10005
</TABLE>
 
    DELIVERY OF THIS NOTICE OF GUARANTEED DELIVERY TO AN ADDRESS OTHER THAN AS
SET FORTH ABOVE WILL NOT CONSTITUTE A VALID DELIVERY.
 
    THIS NOTICE OF GUARANTEED DELIVERY IS NOT TO BE USED TO GUARANTEE
SIGNATURES. IF A SIGNATURE ON A LETTER OF TRANSMITTAL IS REQUIRED TO BE
GUARANTEED BY AN "ELIGIBLE INSTITUTION" UNDER THE INSTRUCTIONS THERETO, SUCH
SIGNATURE GUARANTEE MUST APPEAR IN THE APPLICABLE SPACE PROVIDED IN THE
SIGNATURE BOX ON THE LETTER OF TRANSMITTAL.
<PAGE>
Ladies and Gentlemen:
 
    The undersigned hereby tenders to ALB Acquisition Corporation, a Delaware
corporation (the "Purchaser") and a wholly-owned subsidiary of Vulcan Materials
Company, a New Jersey corporation, upon the terms and subject to the conditions
set forth in the Offer to Purchase, dated November 20, 1998 (the "Offer to
Purchase"), and in the related Letter of Transmittal (which together constitute
the "Offer"), receipt of each of which is hereby acknowledged, the number of
Shares (including the associated common share purchase rights) indicated below
pursuant to the guaranteed delivery procedures set forth in Section 3 of the
Offer to Purchase.
 
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<S>                                            <C>
 
Number of Shares (specify number of each       Name(s) of Record Holder(s):
type):
                                               Please Print
Certificate Nos. (if available)                Address(es):
Include account number if Shares will be       Zip Code
tendered by book-entry transfer (including     Area Code and Tel. No.:
through DTC's ATOP):                           Signature(s):
Account Number:
                                               Dated: , 1998
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<PAGE>
                     THE GUARANTEE BELOW MUST BE COMPLETED
 
                                   GUARANTEE
 
                    (NOT TO BE USED FOR SIGNATURE GUARANTEE)
 
    The undersigned, a firm that is a bank, broker, dealer, credit union,
savings association or other entity which is a member in good standing of the
Securities Transfer Agents Medallion Program, hereby guarantees to deliver to
the Depositary at one of its addresses set forth above either the certificates
representing all tendered Shares, in proper form for transfer, a Book-Entry
Confirmation (as defined in the Offer to Purchase), together with a properly
completed and duly executed Letter of Transmittal (or facsimile thereof), with
any required signature guarantees, or, in the case of book-entry delivery of
Shares, an Agent's Message (as defined in the Offer to Purchase), and any other
documents required by the Letter of Transmittal within three New York Stock
Exchange trading days after the date of execution of this Notice of Guaranteed
Delivery. A "New York Stock Exchange trading day" is any day on which The New
York Stock Exchange is open for business.
 
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<S>                                            <C>
 
                Name of Firm                   Authorized Signature
                   Address                     Title
                                               Name:
                                    Zip Code   Please Print
  Area Code and Tel. No.:                      Date: , 1998
</TABLE>
 
    NOTE: DO NOT SEND SHARE CERTIFICATES WITH THIS NOTICE OF GUARANTEED
          DELIVERY. SHARE CERTIFICATES SHOULD BE SENT WITH YOUR LETTER OF
          TRANSMITTAL.
 
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