<PAGE>
 
                                 UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C.  20549

                                   FORM 10-Q

(Mark One)
[X]  QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
     ACT OF 1934

               FOR THE QUARTERLY PERIOD ENDED SEPTEMBER 30, 1997

                                       OR

[ ]  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
     EXCHANGE ACT OF 1934

     FOR THE TRANSITION PERIOD FROM               TO
                                   ---------------   ----------------
     Commission File Number 1-7035

                                   CALMAT CO.

-------------------------------------------------------------------------------
             (Exact name of registrant as specified in its charter)
 
           Delaware                                           95-0645790
-------------------------------                           ------------------
(State or other jurisdiction of                           (I.R.S. employer
incorporation or organization)                            Identification No.)
 
           3200 San Fernando Road, Los Angeles, California    90065
--------------------------------------------------------------------------------
            (Address of principal executive offices)          (ZIP Code)
 
Registrant's telephone number, including area code                (213) 258-2777
                                                                  --------------

Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the registrant was
required to file such reports), and (2) has been subject to such filing
requirements for the past 90 days.

                                                                 YES [X]  NO [ ]

APPLICABLE ONLY TO ISSUERS INVOLVED IN BANKRUPTCY PROCEEDINGS DURING THE
PRECEDING FIVE YEARS:

Indicate by check mark whether the registrant has filed all documents and
reports required to be filed by Sections 12, 13 or 15(d) of the Securities
Exchange Act of 1934 subsequent to the distribution of securities under a plan
confirmed by a court.

                                                                 YES [ ]  NO [ ]

APPLICABLE ONLY TO CORPORATE ISSUERS:

Indicate the number of shares outstanding of each of the issuer's classes of
common stock, as of the latest practicable date.

23,394,761 shares of Common Stock were outstanding at November 5, 1997.

                                      -1-
<PAGE>
 
                                   CALMAT CO.

                                     INDEX
                                     -----
<TABLE> 
<CAPTION> 

PART I - FINANCIAL INFORMATION                                                      PAGE
<S>                                                                                 <C> 
   Item 1.   Financial Statements

             (a)  Consolidated Balance Sheets:
                  September 30, 1997 and December 31, 1996                            3

             (b) Consolidated Statements of Operations:                               
                 For the Three and Nine Months Ended September 30, 1997 and 1996      4

             (c) Consolidated Statements of Cash Flows:
                 For the Nine Months Ended September 30, 1997 and 1996                5
  
             (d) Notes to Consolidated Financial Statements                           6
 
    Item 2.  Management's Discussion and Analysis of Financial
             Condition and Results of Operations                                      7
 
PART II - OTHER INFORMATION
 
    Item 1.  Legal Proceedings                                                       10
 
    Item 6.  Exhibits and Reports on Form 8-K                                        10
 
     Signatures                                                                      11
</TABLE>

                                      -2-
<PAGE>
 
                                  CALMAT CO.

                          CONSOLIDATED BALANCE SHEETS
                            (amounts in thousands)
<TABLE>
<CAPTION>
 
                                                                                         September 30,   December 31,
                                                                                             1997            1996
                                                                                         -------------   -------------
                                                                                          (unaudited)
<S>                                                                                      <C>             <C>
ASSETS

Current assets:
 Cash and cash equivalents                                                                   $  2,259       $  17,127
 Cash held in trust for section 1031 exchanges                                                    425           8,648
 Trade accounts receivable, less allowance
   for discounts and doubtful accounts
   ($6,240 in 1997 and $5,309 in 1996)                                                         86,348          52,558
 Income taxes receivable                                                                            -           1,395
 Inventories                                                                                   16,988          13,972
 Prepaid expenses and other                                                                     4,558           4,335
 Deferred income taxes                                                                         11,867          11,867
 Installment notes receivable-current portion                                                     233             337
                                                                                             --------       ---------
     Total current assets                                                                     122,678         110,239
Installment notes receivable and other assets                                                  35,544          28,602
Costs in excess of net assets of businesses acquired, net                                      49,142          50,410
Property, plant and equipment, at cost:
 Land and deposits                                                                            195,909         183,516
 Buildings, machinery and equipment                                                           514,266         495,320
 Construction in progress                                                                      33,846          31,763
                                                                                             --------       ---------
                                                                                              744,021         710,599
 Less:  Accumulated depreciation and depletion                                               (313,195)       (299,134)
                                                                                             --------       ---------
     Property, plant and equipment, net                                                       430,826         411,465
                                                                                             --------       ---------
     Total assets                                                                            $638,190       $ 600,716
                                                                                             ========       =========
 
     LIABILITIES AND STOCKHOLDERS' EQUITY
 
Current liabilities:
 Accounts payable                                                                            $ 32,212       $  20,208
 Accrued liabilities                                                                           42,215          34,905
 Notes and bonds payable - current portion                                                        331             100
 Income taxes payable                                                                           3,285               -
 Dividends payable                                                                              2,327           2,324
                                                                                             --------       ---------
   Total current liabilities                                                                   80,370          57,537
Notes and bonds payable - long term portion                                                   121,651         116,233
Other liabilities and deferred credits                                                         38,342          38,429
Deferred income taxes                                                                          56,490          56,325
                                                                                             --------       ---------
   Total liabilities                                                                          296,853         268,524
                                                                                             --------       ---------
Stockholders' equity:
 Common stock                                                                                  23,349          23,240
 Additional paid-in capital                                                                    43,435          41,521
 Retained earnings                                                                            274,553         267,431
                                                                                             --------       ---------
   Total stockholders' equity                                                                 341,337         332,192
                                                                                             --------       ---------
   Total liabilities and stockholders' equity                                                $638,190       $ 600,716
                                                                                             ========       =========
 
</TABLE>
See accompanying notes to consolidated financial statements.

                                      -3-
<PAGE>
                                  CALMAT CO.
 
                     CONSOLIDATED STATEMENTS OF OPERATIONS
           (unaudited, amounts in thousands, except per share data)
<TABLE>
<CAPTION>
 
 
                                                   Three months ended     Nine months ended 
                                                      September 30,         September 30,  
                                                     1997       1996       1997      1996           
                                                   --------   --------   --------   --------           
<S>                                                <C>        <C>        <C>       <C>         
Revenues:                                                                                      
 Net sales and operating revenues                  $132,074   $114,978   $336,580   $300,542         
 Gains on sales of real estate                        2,607        832      4,173      2,632         
 Other income                                         1,662        750      4,646      2,724         
                                                   --------   --------   --------   --------         
                                                    136,343    116,560    345,399    305,898         
                                                   --------   --------   --------   --------         
                                                                                                    
Costs and expenses:                                                                                 
 Cost of products sold and operating expenses       109,885     96,573    286,024    257,379         
 Selling, general and administrative expenses        10,894      9,208     31,930     28,532         
 Interest expense                                     1,941      1,668      5,787      3,945         
 Other expense                                          337        516        797      1,346         
                                                   --------   --------   --------   --------         
                                                    123,057    107,965    324,538    291,202         
                                                   --------   --------   --------   --------         
                                                                                                    
Income before income taxes                           13,286      8,595     20,861     14,696         
                                                                                                    
Federal and state income taxes                        4,022      3,401      6,749      5,658         
                                                   --------   --------   --------   --------         
                                                                                                    
Net income                                         $  9,264   $  5,194   $ 14,112   $  9,038         
                                                   ========   ========   ========   ========         
                                                                                                    
Per Share Data:                                                                                     
                                                                                                    
Net income                                         $   0.39   $   0.22   $   0.60   $   0.39         
                                                   ========   ========   ========   ========         
 
Weighted average shares outstanding                  23,503     23,252     23,360     23,236         
                                                   ========   ========   ========   ========         
                                                                                                    
Cash dividends per share                           $   0.10   $   0.10   $   0.30   $   0.30         
                                                   ========   ========   ========   ========         
 
</TABLE>

See accompanying notes to consolidated financial statements.

                                      -4-
<PAGE>
                                  CALMAT CO.
 
                     CONSOLIDATED STATEMENTS OF CASH FLOWS
                       (unaudited, amounts in thousands)
<TABLE>
<CAPTION>
 
 
                                                                                      Nine months ended
                                                                                         September 30,
                                                                                       1997        1996
                                                                                   --------    --------
<S>                                                                                <C>         <C>
OPERATING ACTIVITIES:
 Net income                                                                        $ 14,112    $  9,038
 Depreciation, cost depletion and amortization                                       26,213      23,309
 Other                                                                              (25,532)     (4,649)
                                                                                   --------    --------
  Cash provided by operating activities                                              14,793      27,698
                                                                                   --------    --------
 
 
 
INVESTING ACTIVITIES:
 Purchase of property, plant and equipment                                          (28,223)    (50,323)
 Proceeds from sale of real estate                                                   11,272       2,827
 Businesses acquired                                                                (23,610)          -
 Installment notes receivable                                                           398       6,395
 Other                                                                                1,187         767
                                                                                   --------    --------
 
  Cash used for investing activities                                                (38,976)    (40,334)
                                                                                   --------    --------
 
 
 
FINANCING ACTIVITIES:
 Notes payable to banks                                                               9,000      19,250
 Principal payments on notes and bonds payable                                       (3,127)        (60)
 Payment of cash dividends                                                           (6,972)     (6,960)
 Other                                                                                2,191       1,259
                                                                                   --------    --------
 
  Cash provided by financing activities                                               1,092      13,489
                                                                                   --------    --------
 
Increase/(decrease) in cash                                                         (23,091)        853
Increase/(decrease) in cash held in trust for section 1031 exchanges                 (8,223)        853
                                                                                   --------    --------
Decrease in cash and cash equivalents                                               (14,868)          -
 Cash and cash equivalents, beginning of period                                      17,127           -
                                                                                   --------    --------
 Cash and cash equivalents, end of period                                          $  2,259    $      -
                                                                                   ========    ========
 
</TABLE>
See accompanying notes to consolidated financial statements.

                                      -5-
<PAGE>
 
                                  CALMAT CO.

                  NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                                  (unaudited)



1. In the opinion of management, information furnished herein reflects all
   adjustments necessary for a fair presentation of the financial position and
   results of operations for the interim periods.  There have been no changes in
   the significant accounting policies as discussed in Note 1 of Notes to
   Financial Statements contained in the Company's 1996 Annual Report on Form
   10-K.

2. Earnings per common equivalent share (common shares adjusted for dilutive
   effect of common stock options) have been computed by dividing net income for
   each period by the weighted-average equivalent shares of common stock
   outstanding.

3. In February 1997 the Financial Accounting Standards Board issued Statement of
   Financial Accounting Standards ("SFAS") No. 128, "Earnings Per Share".  SFAS
   No. 128 is required to be implemented for financial statements for both
   interim and annual periods ending after December 15, 1997.  Based on a review
   of the requirements of SFAS No. 128, management does not anticipate any
   material change in previously reported earnings per share.

4. Certain prior year amounts have been restated to conform to the current
   year's presentation.

                                      -6-
<PAGE>
 
                                  CALMAT CO.

Item 2. Management's Discussion and Analysis of Financial Condition and Results
-------------------------------------------------------------------------------
of Operations
-------------

Results of Operations
---------------------

The Company reported net income of $9.3 million, or $0.39 per share, for the
third quarter of 1997, compared with $5.2 million, or $0.22 per share, for the
prior year's third quarter.  Net income was $14.1 million, or $0.60 per share,
for the nine months ended September 30, 1997, compared with net income of $9.0
million, or $0.39 per share, for the comparable period in 1996.

Business segment information for the three and nine months ended September 30,
1997 and 1996 is as follows:
<TABLE>
<CAPTION>
 
                                                                 Three Months Ended        Nine Months Ended
                                                                     September 30,             September 30,
                                                                   1997         1996          1997        1996
                                                               --------     --------     ---------   ---------
                                                                        (unaudited, amounts in thousands)
<S>                                                           <C>          <C>          <C>         <C>
Revenues:
 
Construction Materials                                         $126,887     $109,448     $321,310    $284,077
Properties - Operations                                           5,187        5,530       15,270      16,465
Properties - Real Estate Gains                                    2,607          832        4,173       2,632
Corporate and Other                                               1,662          750        4,646       2,724
                                                               --------     --------     --------    --------
                                                               $136,343     $116,560     $345,399    $305,898
                                                               ========     ========     ========    ========
                                                                       
                                                                       
                                                                       
Income before income taxes:                                            
                                                                       
Construction Materials                                         $ 12,462     $  9,743     $ 22,294    $ 16,974
Properties - Operations                                           2,229        2,658        6,998       7,486
Properties - Real Estate Gains                                    2,607          832        4,173       2,632
Corporate and Unallocated Expenses, Net                          (3,348)      (2,927)      (9,943)     (8,946)
Interest Expense                                                 (1,941)      (1,668)      (5,787)     (3,945)
Other Income (Expense)                                            1,277          (43)       3,126         495
                                                               --------     --------     --------    --------
                                                               $ 13,286     $  8,595     $ 20,861    $ 14,696
                                                               ========     ========     ========    ========
 
</TABLE>

Income before income taxes by segment represents total revenues less direct
operating expenses, segment selling, general and administrative expenses and
certain allocated corporate general and administrative expenses.  Corporate and
Unallocated Expenses, Net includes corporate administrative expenses and support
expenses not allocated to business segments.  Other Income (Expense) includes
interest income and other miscellaneous items.

                                      -7-
<PAGE>
 
                                  CALMAT CO.


Construction Materials Division
-------------------------------

Sales volumes are shown below.
<TABLE>
<CAPTION>
 

                    
Amounts in Thousands  (unaudited)                        Three Months Ended     Nine Months Ended    
--------------------                                        September 30,          September 30,
                                                           1997       1996        1997        1996       
                                                          -----      -----      ------      ------       
<S>                                                      <C>        <C>        <C>         <C>          
Aggregates:                                                                                             
Tons sold to outside customers                            5,357      4,603      14,671      12,883       
Tons used in ready mixed concrete                           832        767       2,305       2,331       
Tons used in asphalt                                      1,807      1,573       4,303       3,801       
                                                          -----      -----      ------      ------       
                                                          7,996      6,943      21,279      19,015       
                                                          =====      =====      ======      ======       
                                                                                                        
Tons of hot-mix asphalt sold                              2,585      2,297       6,067       5,448       
                                                          =====      =====      ======      ======       
                                                                                                        
Yards of ready mixed concrete sold                          667        630       1,861       1,800       
                                                          =====      =====      ======      ======       
 
</TABLE>

Revenues in the Construction Materials Division were $126.9 million in the third
quarter of 1997, up $17.4 million, or 16% compared with the corresponding 1996
period, and $321.3 million in the first nine months of 1997, up $37.2 million,
or 13% compared with the same period in 1996.  The revenue increase for the
current quarter and nine-month period was due to higher unit sales volumes and
average selling prices for aggregates, ready mixed concrete and asphalt
operations.

The Division's pre-tax income from operations was $12.5 million in the third
quarter compared with $9.7 million in the year earlier period.  The improved
results reflect higher earnings from our aggregates and asphalt operations.
Sales volumes increased 15% for aggregates and 13% for asphalt, while average
selling prices increased 2% for both aggregates and asphalt.  Ready mixed
concrete results were lower despite a 6% increase in sales volumes and 2% higher
average selling prices.  The decline was due to 5% higher unit production costs,
which was largely the result of higher cement costs.

The Division's pre-tax income from operations for the first nine months was
$22.3 million compared with $17.0 million in the 1996 period. The improved
earnings largely stem from the Company's aggregates operations which had 12%
higher sales volumes, 6% higher average selling prices and flat unit production
costs.  Also contributing to the improved earnings were the Company's asphalt
operations which had 11% higher sales volumes, 1% higher average selling prices
and flat unit production costs.  Ready mixed concrete results were lower despite
a 3% increase in sales volumes and 2% higher average selling prices.  The
decline was due to 4% higher unit production costs, with more than one-half the
result of increased cement costs.

Properties Division
-------------------

Revenues in the Properties Division, excluding gains on sales of real estate,
were $5.2 million in the third quarter of 1997 compared with $5.5 million in the
corresponding 1996 period, and $15.3 million in the first nine months of 1997
compared with $16.5 million in the first nine months of 1996.  The decrease in
revenue for the current quarter and nine-month  period was largely due to
decreased revenues from developed properties which, in turn, was caused by
recent sales of such properties.

The Division's pre-tax income from operations increased to $4.8 million for the
third quarter of 1997 compared with $3.5 million in the prior year's third
quarter.  The current quarter includes $2.6 million of gains from real estate
sales, compared with gains of $0.8 million in the prior year's quarter.
Excluding real estate gains, the Division's pre-tax income from operations
declined $0.4 million, due in part to recent sales of income-producing property.

The Division's pre-tax income from operations increased to $11.2 million in the
first nine months of 1997 compared with $10.1 million in the prior period. Gains
from real estate sales of $4.2 million are included in 1997 versus gains of $2.6
million in 1996. Excluding real estate gains, the Division's pre-tax income from
operations decreased $0.5 million, due in part to recent sales of income-
producing property.

                                      -8-
<PAGE>
 
                                  CALMAT CO.


Other
-----

Interest expense was $0.3 million higher in the third quarter of 1997, compared
with the prior year's quarter, and $1.8 million higher in the first nine months
of 1997, compared with the prior year, due to higher levels of average debt
outstanding and higher weighted-average interest rates.  The higher average
interest rate results from a long-term debt refinancing accomplished in late
1996.

The income tax provision in the third quarter and in the first nine months of
1997 includes a $0.8 million tax benefit as a result of a settlement of a prior
year tax claim related to the sale of a landfill operation.

Other income in the third quarter and in the first nine months of 1997 includes
$1.0 million of interest income related to the landfill tax settlement.  Other
income in the first nine months of 1997 also includes a $1.1 million refund
received as settlement of a prior year tax claim of a former subsidiary.

Liquidity and Capital Resources
-------------------------------

Cash and cash equivalents were $2.3 million at September 30, 1997 compared with
$17.1 million at December 31, 1996. Cash provided by operating activities was
$14.8 million for the nine months ended September 30, 1997.  Cash used for
investing activities was $39.0 million, including $28.2 million for the purchase
of property, plant  and equipment and $23.6 million for business acquisitions,
partially offset by proceeds from the sales of real estate of $11.3 million.
Cash provided by financing activities was $1.1 million, including a $5.9 million
net increase in debt, and a $2.0 million increase in stock options exercised,
partially offset  by cash dividends of  $7.0 million.

Working capital totaled $42.3 million at September 30, 1997, a  $10.4 million
decrease from $52.7 million  at December 31, 1996.  The decrease in working
capital was due to a  $23.1 million decrease in cash and a $19.3 million
increase in accounts payable and accrued liabilities, partially offset by a
$33.8 million increase in trade accounts receivable.  Current ratios were 1.5
and 1.9 at September 30, 1997 and December 31, 1996, respectively.

Total consolidated long-term and short-term borrowings at September 30, 1997 and
December 31, 1996 were $122.0 million and $116.3 million, respectively.  Debt as
a percent of total capitalization was 26.3% and 25.9%, at September 30, 1997 and
December 31, 1996, respectively.

Other
-----

The Company announced on October 7, 1997 that it will emphasize growth of its
core construction materials business by selling its industrial and office
properties, and by accelerating the sale of 9,584 acres of property not being
used in its construction materials business, including prime sites currently
available for development.  These properties are located in Los Angeles, San
Diego, Phoenix and Albuquerque and have a book value of approximately $93
million.  The Company expects to sell these assets over the next two years with
expected proceeds of between $150 million and $170 million.  The Company will
continue to own in excess of 20,000 acres, and will sell properties as they are
no longer used in the construction materials business.

                                      -9-
<PAGE>
 
                                  CALMAT CO.

                          PART II - OTHER INFORMATION



Item 1. Legal Proceedings
-------------------------

Operating Industries, Inc. Landfill Site
----------------------------------------

In 1988, the U.S. Environmental Protection Agency ("EPA"), the State of
California and the California Hazardous Substance Account named the Company and
over 200 other parties defendants in a civil action alleging joint and several
liability pursuant to certain California statutes and the Comprehensive
Environmental Response, Compensation and Liability Act ("CERCLA") in connection
with the cleanup of the former Operating Industries, Inc. landfill site in
Monterey Park, California.  The EPA's current allegation is that the Company
disposed of hazardous substances representing 0.0675 percent of the total volume
of waste at the site.  The Company believes, however, that the substances
attributed to it at the site were not hazardous.

To date, the Company has contributed approximately $300,000 to fund certain
interim remedial actions at the site, as part of two partial settlements of this
matter (which in part remain subject to court approval). The EPA recently
reached a decision as to the Final Remedy to be implemented for the site and
currently estimates the total cost for implementation to be shared by all
parties to be $289 million.

Although the Company's share of any liability is still undetermined, and the
ultimate outcome of this action cannot be predicted with certainty, the Company
believes that this matter will be resolved without a material adverse effect on
its financial position or results of operations.  The Company's belief is based
on its position that the wastes  attributed to it at the site were not
hazardous, its extremely small share of the waste at the site compared to wastes
attributable to the other defendants, and its belief that it has recourse to
insurance coverage for at least a substantial portion of any resulting
liability.


Item 6. Exhibits and Reports on Form 8-K
----------------------------------------


(a)  Exhibit 4.1: Amendment #1 to Form 8-A for Registration of Certain Classes
     of Securities, dated and filed with the Securities and Exchange Commission
     on September 30, 1997, is incorporated herein by reference.

(b)  Exhibit 27. Financial Data Schedule

                                      -10-
<PAGE>
 
                                  CALMAT CO.

                                  SIGNATURES
                                  ----------


Pursuant to the requirements of the Securities Exchange Act of 1934, Registrant
has duly caused this report to be signed on its behalf by the undersigned
thereunto duly authorized.



 
                                         CALMAT CO.                            
                                     --------------------------------         
                                         (Registrant)                          
                                                                               
                                                                               
                                                                               
Date:  November 10, 1997             By:/s/H. James Gallagher                  
                                        ---------------------------------- 
                                        H. James Gallagher                     
                                        Executive Vice President, Finance,
                                        Chief Financial Officer and            
                                        Treasurer                              
                                                                               
                                                                               
                                                                               
                                                                               
Date:  November 10, 1997             By:/s/Brent L. Stumme                     
                                        ------------------------------------
                                        Brent L. Stumme                        
                                        Vice President, Corporate Controller

                                      -11-