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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-04-27</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001188420</rptOwnerCik>
            <rptOwnerName>MCGREGOR DOUGLAS J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1200 URBAN CENTER DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BIRMINGHAM</rptOwnerCity>
            <rptOwnerState>AL</rptOwnerState>
            <rptOwnerZipCode>35242</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>2004-04-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>31.552</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>47.541</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>1988-08-08</value>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>1988-08-08</value>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>31.552</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>35218.043</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>2004-04-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0202
4
2004-04-27
0
0000103973
VULCAN MATERIALS CO
VMC
0001188420
MCGREGOR DOUGLAS J
1200 URBAN CENTER DRIVE
BIRMINGHAM
AL
35242
1
0
0
0
Phantom Stock (Deferred Compensation)
0
2004-04-27
4
A
0
31.552
47.541
A
1988-08-08
1988-08-08
Common Stock
31.552
35218.043
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
2004-04-29