
<PAGE>


                                                              EXHIBIT (a)(8)


     This announcement is neither an offer to purchase nor a solicitation of
        an offer to sell Shares. The Offer is made solely by the Offer to
    Purchase, dated November 20, 1998, and the related Letter of Transmittal,
   and is being made to all holders of Shares. The Offer is not being made to
    (nor will tenders be accepted from or on behalf of) holders of Shares in
   any jurisdiction in which the making of the Offer or the acceptance thereof
      would not be in compliance with the laws of such jurisdiction. In any
        jurisdiction where the securities, blue sky or other laws require
     the Offer to be made by a licensed broker or dealer, the Offer shall be
    deemed to be made on behalf of ALB Acquisition Corporation by Goldman, 
      Sachs & Co. or one or more registered brokers or dealers licensed 
                    under the laws of such jurisdiction.


                      Notice of Offer to Purchase for Cash
                     All Outstanding Shares of Common Stock
             (Including the Associated Common Share Purchase Rights)

                                       of

                                   CALMAT CO.

                                       by

                          ALB Acquisition Corporation

                          a wholly-owned subsidiary of

                            Vulcan Materials Company

                                       at

                              $31.00 Net Per Share

         ALB Acquisition Corporation (the "Purchaser"), a Delaware 
corporation and a wholly-owned subsidiary of Vulcan Materials Company, a New 
Jersey corporation ("Parent"), is offering to purchase all outstanding shares 
of Common Stock, par value $1 per share (the "Shares"), of CalMat Co., a 
Delaware corporation (the "Company"), and the associated common share 
purchase rights (the "Rights") issued pursuant to the Rights Agreement, dated 
as of September 22, 1987, as amended as of October 26, 1992, July 22, 1997, 
and November 14, 1998, between the Company and First Chicago Trust Company of 
New York, as Rights Agent (as the same may be

<PAGE>


amended, the "Rights Agreement"), at a purchase price of $31.00 per Share (and
associated Right), net to the seller in cash, without interest thereon, 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"). Unless the context
otherwise requires, all references to Shares herein and in the Offer to Purchase
shall include the associated Rights.

-------------------------------------------------------------------------------
THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT NEW YORK CITY
TIME, ON FRIDAY, JANUARY 1, 1999, UNLESS THE OFFER IS EXTENDED.
-------------------------------------------------------------------------------

         The Offer is being made pursuant to an Agreement and Plan of Merger, 
dated as of November 14, 1998 (the "Merger Agreement"), by and among the 
Company, the Purchaser and Parent pursuant to which, following the 
consummation of the Offer and the satisfaction of certain conditions, the 
Purchaser will be merged with and into the Company (the "Merger"), with the 
Company continuing as the surviving corporation. On the effective date of the 
Merger, each outstanding Share (other than any Shares held by Parent, the 
Purchaser, any wholly-owned subsidiary of Parent or the Purchaser, in the 
treasury of the Company or by any wholly-owned subsidiary of the Company, 
which Shares will be canceled with no payment being made with respect 
thereto, and other than Shares, if any, held by stockholders who perfect 
their appraisal rights under Delaware law) will be converted into the right 
to receive an amount equal to $31.00 in cash (without interest).

         The Board of Directors of the Company unanimously has determined 
that the Offer and the Merger are fair to and in the best interests of the 
stockholders of the Company, has approved the Offer and the Merger Agreement 
and recommends acceptance of the Offer by the Company's stockholders.

         THE OFFER IS CONDITIONED UPON, AMONG OTHER THINGS,  SHARES 
REPRESENTING AT LEAST A MAJORITY OF THE TOTAL NUMBER OF OUTSTANDING SHARES ON 
A FULLY DILUTED BASIS BEING VALIDLY TENDERED AND NOT PROPERLY WITHDRAWN PRIOR 
TO THE EXPIRATION OF THE OFFER. THE OFFER IS ALSO SUBJECT TO OTHER TERMS AND 
CONDITIONS. SEE THE INTRODUCTION AND SECTIONS 1, 14 AND 15 OF THE OFFER TO 
PURCHASE.

         For purposes of the Offer, the Purchaser will be deemed to have 
accepted for payment, and thereby purchased, Shares validly tendered and not 
withdrawn as, if and when the Purchaser gives oral or written notice to First 
Chicago Trust Company of New York, as depositary (the "Depositary") of the 
Purchaser's acceptance of such Shares for payment pursuant to the Offer. In 
all cases, upon the terms and subject to the conditions of the Offer, payment 
for Shares purchased pursuant to the Offer will be made by deposit of the 
purchase price therefor with the Depositary, which will act as agent for 
tendering stockholders for the purpose of receiving payment from the 
Purchaser and transmitting payment to validly tendering stockholders. Under 
no circumstances will interest on the purchase price for Shares be paid by 
the Purchaser. In all cases, payment for Shares purchased pursuant to the 
Offer will be made only after timely receipt by the Depositary of (i) 
certificates representing Shares (the "Share Certificates") for such Shares 
or timely confirmation of the book-entry transfer of such Shares into the 
Depositary's account at The Depository Trust Company (the "Book-Entry

                                       2

<PAGE>


Transfer Facility") pursuant to the procedures set forth in Section 3 of the 
Offer to Purchase, (ii) the Letter of Transmittal (or a facsimile thereof), 
properly completed and duly executed, with any required signature guarantees 
or an Agent's Message (as defined in the Offer to Purchase) in connection 
with a book-entry transfer of Shares and (iii) any other documents required 
by the Letter of Transmittal.

         The Purchaser expressly reserves the right, in its sole discretion 
(subject to the terms and conditions of the Merger Agreement), at any time 
and from time to time, to extend the period during which the Offer is open 
for any reason, including the existence of any of the conditions specified in 
Section 14 of the Offer to Purchase, by giving oral or written notice of such 
extension to the Depositary. Any such extension will be followed as promptly 
as practicable by public announcement thereof, and such announcement will be 
made no later than 9:00 a.m., New York City time, on the next business day 
after the previously scheduled Expiration Date (as defined below).

         Tenders of Shares made pursuant to the Offer are irrevocable, except 
that Shares tendered pursuant to the Offer may be withdrawn at any time on or 
prior to the Expiration Date and, unless theretofore accepted for payment as 
provided in the Offer to Purchase, may also be withdrawn at any time after 
Monday, January 18, 1999. The term "Expiration Date" means 12:00 midnight, 
New York City time, on Friday, January 1, 1999, unless and until the 
Purchaser, subject to the terms of the Merger Agreement, shall have further 
extended the period of time for which the Offer is open, in which event the 
term "Expiration Date" shall mean the latest time and date at which the 
Offer, as so extended by the Purchaser, shall expire. In order for a 
withdrawal to be effective, a written or facsimile transmission notice of 
withdrawal must be timely received by the Depositary at one of its addresses 
set forth on the back cover of the Offer to Purchase. Any such notice of 
withdrawal must specify the name of the person who tendered the Shares to be 
withdrawn, the number of Shares to be withdrawn, and (if Share Certificates 
have been tendered) the name of the registered holder of the Shares as set 
forth in the Share Certificate, if different from that of the person who 
tendered such Shares. If Share Certificates have been delivered or otherwise 
identified to the Depositary, then prior to the physical release of such 
certificates, the tendering stockholder must submit the serial numbers shown 
on the particular certificates evidencing the Shares to be withdrawn and the 
signature on the notice of withdrawal must be guaranteed by 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 (an "Eligible Institution"), except in the case of Shares tendered 
for the account of an Eligible Institution. If Shares have been tendered 
pursuant to the procedures for book-entry transfer set forth in Section 3 of 
the Offer to Purchase, the notice of withdrawal must specify the name and 
number of the account at the Book-Entry Transfer Facility to be credited with 
the withdrawn Shares, in which case a notice of withdrawal will be effective 
if delivered to the Depositary by any method of delivery described in this 
paragraph. All questions as to the form and validity (including time of 
receipt) of notices of withdrawal will be determined by the Purchaser, in its 
sole discretion, whose determination shall be final and binding. Any Shares 
properly withdrawn will be deemed not validly tendered for purposes of the 
Offer, but may be tendered at any subsequent time prior to the Expiration 
Date by following any of the procedures described in Section 3 of the Offer 
to Purchase.

                                       3

<PAGE>


         The information required to be disclosed pursuant to Rule
14d-6(e)(1)(vii) of the General Rules and Regulations under the Securities
Exchange Act of 1934, as amended, is contained in the Offer to Purchase, and is
incorporated herein by reference.

         The Company is providing the Purchaser with the Company's stockholder
list and security position listings for the purpose of disseminating the Offer
to holders of Shares. The Offer to Purchase and the related Letter of
Transmittal and, if required, other relevant materials will be mailed to record
holders of Shares and will be furnished to brokers, dealers, commercial banks,
trust companies and similar persons whose names, or the names of whose nominees,
appear on the stockholder list or who are listed as participants in a clearing
agency's security position listing for subsequent transmittal to beneficial
owners of Shares.

         The Offer to Purchase and the related Letter of Transmittal contain
important information which should be read carefully before any decision is made
with respect to the Offer.

         Questions and requests for assistance may be directed to the 
Information Agent or the Dealer Managers at their respective  addresses and 
telephone numbers listed below. Additional copies of the Offer to Purchase, 
the Letter of Transmittal, the Notice of Guaranteed Delivery and other 
related materials may be obtained at the Purchaser's expense from the 
Information Agent or from brokers, dealers, commercial banks and trust 
companies. Neither Parent nor the Purchaser will pay any fees or commissions 
to any broker, dealer or other person for soliciting tenders of Shares 
pursuant to the Offer.

                     The Information Agent for the Offer is:

                            GEORGESON & COMPANY INC.
                                Wall Street Plaza
                            New York, New York 10005

                 Banks and Brokers Call Collect: (212) 440-9800
                    ALL OTHERS CALL TOLL-FREE (800) 223-2064

                   The Dealer Managers for the Offer are:

                             GOLDMAN, SACHS & CO.
                               85 Broad Street
                           New York, New York 10004
                               (800) 323-5678

November 20, 1998


                                       4
