<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-07-08</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000103973</issuerCik>
        <issuerName>VULCAN MATERIALS CO</issuerName>
        <issuerTradingSymbol>VMC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001188414</rptOwnerCik>
            <rptOwnerName>DESIMONE LIVIO D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3050 MINNESOTA WORLD TRADE CENTER</rptOwnerStreet1>
            <rptOwnerStreet2>30 SEVENTH STREET EAST</rptOwnerStreet2>
            <rptOwnerCity>ST. PAUL</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55101-4901</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock (Deferred Compensation)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-07-08</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>64.548</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>46.477</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>64.548</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>30509.639</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock (Deferred Compensation)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-07-09</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>349.425</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>46.505</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>349.425</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>30859.064</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Convertible on a 1-for-1 basis.</footnote>
        <footnote id="F2">Director's fees credited to the reporting person's account in accordance with the Vulcan Materials Company Directors' Deferred Compensation Plan.</footnote>
        <footnote id="F3">The units are to be settled in Vulcan common stock commencing at the retirement of the reporting person.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Amy M. Tucker</signatureName>
        <signatureDate>2004-07-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0202
4
2004-07-08
0
0000103973
VULCAN MATERIALS CO
VMC
0001188414
DESIMONE LIVIO D
3050 MINNESOTA WORLD TRADE CENTER
30 SEVENTH STREET EAST
ST. PAUL
MN
55101-4901
1
0
0
0
Phantom Stock (Deferred Compensation)
0
2004-07-08
4
A
0
64.548
46.477
A
Common Stock
64.548
30509.639
D
Phantom Stock (Deferred Compensation)
0
2004-07-09
4
A
0
349.425
46.505
A
Common Stock
349.425
30859.064
D
Convertible on a 1-for-1 basis.
Director's fees credited to the reporting person's account in accordance with the Vulcan Materials Company Directors' Deferred Compensation Plan.
The units are to be settled in Vulcan common stock commencing at the retirement of the reporting person.
Amy M. Tucker
2004-07-12