IS 4926: Code of Practice Ready-Mixed Concrete

24 Pages·2003·2.1 MB·English

by  Bureau of Indian Standards

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IS 4926 (2003): Code of Practice Ready-Mixed Concrete [CED
2: Cement and Concrete]
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IS 4926:2003

Indian Standard
READY-MIXED CONCRETE — CODE OF PRACTICE
(Second Revision)
Ics 91.100.30

0 BIS2003
BUREAU OF INDIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI I1OOO2

May 2003
Price Group 8
Cement and Concrete Sectional Committee, CED 2
FOREWORD
This Indian Standard (Second Revision) was adopted bythe Bureau of Indian Standards, after the draft finalized
bytheCement and Concrete Sectional Committee had beenapproved bytheCivil Engineering Division Council.
This standard was first published in 1968. The firstrevision ofthestandard wasbrought out in 1976. Inthe first
revision themajor modifications included increase inthetime limitfor supply ofready-mixed concrete byhalf an
hour inorder to make the standard more practicable and permitting useof fly ash.
This second revision isbeing brought out to incorporate modifications found necessary based on the experience
gained withthe useofthisstandard andspecially inthecontext ofrecentdevelopments inthis field inthe couch-y.
The significant modifications included are asfollows :
a) Rationalization of definitions and addition ofdefinitions for more terms.
b) Requirements for materials brought in line with IS 456:2000 ‘Plain and reinforced concrete—Code of
practice’.
c) Minimum testing frequencies introduced for aggregates and water.
d) Basis of supply modified to bring it in line with IS 456:2000 ‘Plain and reinforced concrete—Code of
practice’.
e) Transportation time made uniform to2h.
t) Requirement oftemperature ofconcrete deleted.
g) Sampling procedure hasbeen modified.
h) Tolerance limits forworkability have been modified.
j) Aclause on non-compliance hasbeen included.
k) A detailed clause on production and delivery including plant safety and maintenance and environmental
considerations has been included.
m) Adetai!ed clause on quality control has been included.
n) Adetailed clause on order processing andtraining has been included.

p) Detailed provisions on calibrat ion andweighing equipment accuracy hasbeen introduced asAnnex E.

Foreffective implementation ofthe provisions ofthestandard, itmaybe desirable thatthe ready-mixed concrete
plantsoperate their system under athird partycertification schemetoensure operation ofawell structured system
and to build confidence inthe users of suchconcrete.
The composition ofthe Committee responsible for formulation ofthis standard isgiven atAnnex H.
For the purpose of deciding whether a particular requirement of this standard iscomplied with the final value,
observed orcalculated, expressing theresult ofatestshallberounded offinaccordance with IS2:1960 ‘Rules for
rounding off numerical values (revise@’. The number of significant places retained in the rounded off value
should bethe same asthat ofthe specified value inthis standard.
IS 4926:2003
Indian Standard
READY-MIXED CONCRETE — CODE OF PRACTICE
(Second Revision)
1SCOPE the aggregate in a saturated surface dry condition) to
the mass of cement including mineral additives as
This standard covers the requirements for the
per 4.3 inaconcrete mix.
production andsupplyofready-mixed concrete.Itdoes
notcovertheplacing,compaction, curingorprotection 3.8 Grade of Concrete—Numerical value of
of concrete after delivery. characteristic compressive strength of 150mmcube of
concrete at 28 days, designated by ‘M’ followed by
2REFERENCES
thisstrengthvalueinN/mm*characteristic compressive
strength.
The standards given in Annex A contain provisions
which through reference in this text, constitute
3.9Minimum Cement Content —The minimum mass
provisions ofthisstandard. Atthetime ofpublication,
of cement including mineral additives as per 4.3
the editions indicated were valid. A1lstandards are
required bythepurchaser tobepresent, inunit volume
subjecttorevision, andparties toagreements basedon
of specified mix (see also Note 2 under Table 5 of IS
this standard are encouraged to investigate the
456).
possibility of applying the most recent editions of the
standards indicated inAnnex A. 3.10 Prescribed Mix—Mix for which the purchaser
specifies the proportions of the constituents and is
3TERMINOLOGY
responsible for ensuring that these proportions will
produce aconcrete with the performance required.
3.0 For the purpose of this standard, the following
definitions shall apply.
3.11 Producer— Person or authority entering a
contract to supply ready-mixed concrete.
3.1 Agitator —Truck mounted equipment designed
to agitate concrete during transportation to the siteof
3.12 Purchaser—Person or authority entering a
delivery.
contract to buy ready-mixed concrete.
3.2 Batch —Quantity of concrete mixed inone cycle
3.13 Ready-Mixed Concrete— Concrete mixed in a
of operations of a batch mixer or the quantity of
stationary mixer inacentral batching andmixing plant
concrete conveyed ready-mixed in a vehicle or the
or inatruck-mixer and supplied inthe fresh condition
quantity discharged during 1min from a continuous tothepurchaser eitheratthesiteorintothepurchaser’s
mixer. vehicles.
3.3Characteristic Strength —The value ofstrength
3.14Truck-Mixer —A mixer generally mounted ona
ofconcrete below which notmore than 5 percent of
self-propelledchassis,capableofmixingtheingredients
the population of all possible strength measurements
ofconcrete andofagitating the mixed concrete during
ofthe specified concrete are expected to fall.
transp.ortation.
3.4 Concrete —A mixture of aggregate, cement and 4MATERIALS
water with orwithout admixtures and/or additions and
including entrapped or entrained air, for all uses but 4.1 Selection and Approval of Materials
excluding allmortars otherthanforuseasfloororroof
Materials used should satisfy the requirements for the
screeds.
safety, structural performance, durability and
3.5 Density of Fresh Concrete—Mass of aquantity appearanceofthefinished structure, takingfill account
of compacted fresh concrete divided by its volume, of the environment to which itwill be subjected. The
expressed inkg/m3 inaccordance with IS 1199. selection and use of materials shall be in accordance
with IS 456. Materials used shall conform to the
3.6 Designed Mix—Mix for which the purchaser is relevant Indian Standards applicable. Wherematerials
responsibleforspeci~ing therequiredperformance and areusedwhich arenotcovered bytheprovisions ofthe
the producer is responsible for selecting the mix relevant Indian Standard, there should be satisfactory
proportions to produce the required performance. dataontheirsuitabilityandassuranceofqualitycontrol.
Records and details of performance of such materials
3.7 Free Water-Cement Ratio —Ratio of the mass
should be maintained. Account should be taken of
of free water (that isexcluding the water absorbed by
possible interactions and compatibility between

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IS 4926:2003
materials used. Also,prior permission ofthepurchaser of concrete shall be regulated by controlling its
shall reobtained before useofsuch materials. workability orbymeasuring andadjustingthemoisture
contents of its constituent materials. The producer’s
4.2 Cement—Cement used for concrete shall be in
production staffandtruck-mixer drivers shallbemade
accordance with the requirements of IS456.
aware of the appropriate responses to variations in
concrete consistence of a particular mix caused by
4.3Mineral Admixtures —Useofmineral admixtures
normal variations in aggregate moisture content or
shall bepermitted inaccordance withtheprovisions of
grading.
Is 456.
5GENERAL REQUIREMENTS
4.4 Aggregates —Aggregates used for concrete shall
be in accordance with the requirements of 1S456. 5.1 Basisof Supply
Unless otherwise agreed testing frequencies for
aggregates shall beasgiven inAnnex B. 5.1.1 Ready-mixed concrete shall be supplied having
the quality and inthe quantity inaccordance with the
4.5 Chemical Admixtures requirements agreed with the purchaser or h$sagent.
Notwithstanding this, the concrete supplidd shall
4.5.1 Useofchemical admixtures shallbepermitted in
generally comply with therequirements of 1S456.
accordance with the provisions of IS456.
5.1.2Allconcretewillbesuppliedandinvoicedinterms
4.5.2 It shall be the responsibility of the producer to
of cubic metres (full or part) of compacted fresh
establish compatibility andsuitability ofanyadmixture
concrete. Allproportioning istobecarriedoutbymass
with the other ingredients ofthe mix andto determine
except water and admixture, whichmay be measured
the dosage required to give the desired effect.
by volume.
4.5.3 Admixtures should be stored in a manner that
5.2Transport ofConcrete
prevents degradation of the product and consumed
within the time period indicated by the admixture 5.2.1General
supplier. Any vessel containing an admixture in the
5.2.1.1 Ready-mixed concrete shall be transported
plant or taken to site by the producer shall be clearly
from the mixer to the point of placing as rapidly as
marked asto its content.
practicable bymethods thatwillmaintain the required
4.5.4 Whenoffering ordelivering amixtoapurchaser workability and will prevent segregation, loss of any
it should be indicated if such a mix contains an constituents or ingressofforeign matter orwater. The
admixture or combination of admixtures or not. The concrete shall be placed as soon as possible after
admixtures may be identified generically and should delivery, asclose asispracticable to itsfinal position
bedeclared on the delivery ticket. toavoidrehandlingormovingtheconcretehorizontally
byvibration. Ifrequired bythepurchaser the producer
4.5.5 The amount ofadmixture addedto amix shallbe can utilize admixtures to slow down the rate of

recorded in the production record. In special workability10SSh,oweverthisdoesnotremovetheneed

circumstances, if necessary, addition al dose of for the purchaser to place the concrete as rapidly as
admixture may be added at project site to regain the possible. The purchaser should plan his arrangements
workability of concrete with the mutual agreement soastoenable afull loadofconcrete tobe discharged
between the producer and the purchaser. within 30min ofarrival on site.
4.6 Water 5.2.1.2 Concrete shall betransported inatruck-mixer
unlessthepurchaser agrees tothe use ofnon-agitating
4.6.1 Water used shall be in accordance with the
vehicles. When non-agitating vehicles are used, the
requirements of IS456. Unless otherwise agreed, the
mixed concrete shallbe protected from gain or lossof
testing frequencies for water shall be as given in
water.
Annex B.
5.2.2 Time in Transport
4.6.2 The useof re-cycled water isencouraged aslong
asconcreteofsatisfactoryperformance canbeproduced 5.2.2.1 The general requirement isthat concrete shall
andstepsaretaken tomonitor thebuildup ofchlorides be discharged from the truck-mixer within 2 h of the
in any recirculated water and that any subsequent time Gfloading. However, a longer period may be
adjustments to the mix design are made to ensure that permitted if retarding admixtures are used or in cool
any overall limit on chloride contents issatisfied. The humid weather or when chilled concrete isproduced.
addition ofany recycled water shallbe monitored and
5.2.2.2 The time of loading shallstart from adding the
controlled tomeet these requirements.
mixing water tothe dry mix of cement and aggregate
4.6.3 The total amount ofwater added tothe mix shall orofaddingthecementtothewetaggregatewhichever
berecorded intheproduction record. Thewatercontent isapplicable.

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IS 4926:2003
5.3Ready-mixed concreteplantshallhavetestfacilities 6.3.2 Unless otherwise agreed between the parties
at its premises to carry out routine tests as per the involved, theminimum testing frequency tobeapplied
requirement of the standard. bythe producer inthe absence of arecognized ready-
mixed concrete industry method ofproduction control,
6 SAMPLING AND TESTING OF
should beonesample forevery 50m3ofproduction or
READY-MIXED CONCRETE
every 50 batches, whichever isthe greater frequency.
Threetestspecimens shallbemade upforeach sample
6.1 Point and Time of Sampling
fortesting at28 days (see also IS456).
For the assessment of compliance of ready-mixed
concrete, the point and time of sampling shall be at In order to get a relatively quicker idea of the quality
discharge fromtheproducer’s delivery vehicleorfrom of concrete, optional test on beams for modulus of
the mixer to the site or when delivered into the rupture at72+2horat7daysorcompressive strength
purchaser’s vehicle. It is critical that the sampling testat7days maybe carried out inaddition to28 days
procedure andequipmentusedenablesasrepresentative compressive strength test. For this purpose the value
a sample as possible to be taken of the quantity of shouldbearrived atbasedonactualtesting. Inallcases
concrete delivered (seeAnnex C). 28dayscompressive strength shallalone bethecriteria
for acceptance orrejection ofthe concrete.
The sampling may be carried out jointly by the
purchaser andthe supplier with itsfrequency mutually 6.3.3 The purchaser shall inform the producer if his
agreed upon. However, itwillnotabsolve thesupplier requirements for sampling and testing are higher than
ofhisresponsibility from supplying concrete asperthe one sample every 50 m3or 50 batches, whichever is
the greater frequency.
requirements given inthisstandardorotherwise agreed
towhere sopermitted inthe standard.
6.4 Additional Compliance Criteria
6.2 Workability
Anyadditional compliance criteria shallbedeclared to
the producer bythepurchaser prior tosupply and shall
6.2.1 The test for acceptance isto be performed upon
the producer’s delivery vehicle discharge on site or be mutually agreed upon in terms of definition,
upondischargeintothepurchaser’svehicle.Ifdischarge tolerance, frequency ofassessment, method oftest and
significance of result.
from the producers’ vehicle is delayed on site due to
lack of preparedness on behalf of the purchaser then
6.5 Non-Compliance
theresponsibility passes tothe purchaser after adelay
ofmore than 30 min. The action tobetaken incaseofnon-compliance shall
be declared and mutually agreed upon.
Theworkability shall bewithin thefollowing limitson
the specified value asappropriate: 7 INFORMATION TO BE SUPPLIED BY THE
PURCHASER
Slump + 25 mm or + 1/3 of the
specified valu e, whichever is 7.1 The purchaser shall provide to the producer the
less. details of the concrete mix or mixes required by him
andallpertinent information ontheuseofthe concrete
Compacting factor : +0.03,wherethespecifiedvalue andthe specified requirements. Prior to supply taking
is0.90 or greater, place, itisrecommended thatameeting isheldbetween
* 0.04, where the specified the purchaser andthe producer. Itsobjective to clarify
value islessthan 0.90 butmore operational matters, suchasnotice to begiven prior to
than 0.80, and delivery, delivery rate, the name of the purchaser’s
authorized representative who will coordinate
+0.05,wherethespecifiedvalue
deliveries,anyrequirements foradditional servicessuch
is0.80 or less.
aspumping, on sitetesting or training, etc.
Flowtable test may bespecified for concrete, forvery
7.2 Designed Mixes
high workability (see IS 9103). Acceptance criteria
for spread (flow) are to be established between the Where the purchaser specifies a designed mix to be
supplier and the purchaser. supplied itisessential that all relevant information is
conveyed to the producer. In order to assist in this,
6.3Specified Strength
the format given inAnnex Dmay becompleted and
6.3.1 Compliance shall be assessed against the forwarded tothe producer atthe time of enquiry .
requirementsofIS456orotheragreedIndianStandard.
7.3 Prescribed Mixes
The purchaser may perform his own sampling and
testing or may enter in to an arrangement with the 7.3.1 The concrete mix shall be specified by its
producer to provide his testing requirements. constituent materials and the properties or quantities

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1S 4926:2003
of those constituents to produce a concrete with the Cement shall be stored and stacked in bags and shall
required performance. The assessment of the mix be kept free from the possibility of any dampness or
proportions shall form an essential part of the moisture coming in contact with them and where
compliance requirements. Thepurchaser shallprovide cement can be stored and retrieved without undue
the producer with all pertinent information onthe use damage tothebags. Thebags areto be protected from
oftheconcrete andthespecified requirements. Inorder becoming dampeitherfromtheground orthe weather.
to assist inthis, the format given inAnnex Dmay be The cement is to be used in the order it is delivered
followed with suitable modifications as applicable to (seealso IS4082).
prescribed mixes.
Incase,thecement remains instorage formore than 3
8 INFORMATION TO BE SUPPLIED BY THE months, the cement shall be retested before use and
PRODUCER shall be rejected if it fails to conform to any of the
requirements given inthe relevant Indian Standard.
8.1 When requested, the producer shall provide the
purchaser with the following information before any 9.1.1.2 Dry pulverized fuel ash and other mineral
concrete issupplied: admixtures
a) Nature and source of each constituent material, Suitableseparatearrangement forstorageofpulverized
b) Source of supply of cement, and fuelash,silicafume,metakeolin, ricehuskash,ground
granulated blast furnace slag suchasfor cement, shall
c) Proposed proportions or quantity of each
beprovided, inthe plants utilizing these materials.
constituent/m3 of fresh concrete.
9.1.1.3 Aggregates (coarse andfme)
8.2 When requested, the producer shall provide the
purchaser the following information on admixtures:
Stockpiles shallbefreedraining andarranged to avoid
a) Generic type(s) oftbe mainactiveconstituent(s) contamination and to prevent intermingling with
inthe admixture; adjacentmaterial. Handlingprocedures forloading and
unloading aggregates shall be such as to reduce
b) Whether ornottheadmixture containschlorides
segregation to a minimum. Provision shall be made
and ifso, the chloride content ofthe admixture
for separate storage for each nominal size and type of
expressedasapercentageofchlorideionbymass
aggregate and the method of loading of storage bins
of admixture;
shall be such as to prevent intermingling of different
c) Whether or not the admixture leads to the sizesand types. Fine aggregates shall be stacked ina
entrainment of air when used at the adopted placewhere lossdue totheeffect ofwind isminimum
dosage; (seealso IS4082 and IS456).
d) Where more than one admixture is used,
9.1.1.4 Water
confirmation oftheir compatibility; and
Anadequate supply shallbeprovided andwhen stored
e) Initial and final setting time of concrete when
ontheplant suchstorage facilities shall bedesigned to
admixture isused at adopted dosa ge (tested as
minimize the risks ofcontamination.
per 1S8142).
9 PRODUCTION AND DELIVERY 9.1.1.5 Chemical admixtures
Tanks or drums containing liquid admixtures shall be
9.1 Plant and Equipment
clearly Iabelled for identification purposes and stored
9.1.1 h{ateriul.s Storage and Handling insuchawaytoavoid damage, contamination or the
effectsofprolongedexposuretosunlight(ifapplicable).
9.1.1.1 Cement
Agitationshallbeprovidedforliquidadmixtures,which
Separate storage for different types and grades of arenot stable solutions.
cement shall be provided. Containers may be usedto
9.1.2 Batching Plants and Batching Equipment
store cements of different types provided these are
emptied before loadinganew cement.Binsorsilosshall Hoppers for weighing cement, mineral admixtures,
be weatherproof and permit free flow and efficient aggregates and water and chemical admixture (if
discharge ofthecement. Eachsiloorcompartment ofa measured bymass) shallconsist of suitable containers
si10shall becompletely separate andfittedwithafilter freely suspended fromascale or other suitable load-
oralternative method ofdustcontrol. Eachfilterordust measuring device and equipped with a suitable
control system shall be of sufficient size to allow discharging mechanism. The method ofcontrol ofthe
delivery of cement to be maintained at a specified loadingmechanism shall be such that,asthequantity
pressure, and shall be properly maintained to prevent required in the weighing hopper is approached, the
undueemissionofcementdustandprevent interference material may be added atacontrollable rate andshut
with weighing accuracy by build up of pressure. offprecisely within the weighing tolerances specified

4
IS 4926:2003
inAnnex E.Theweighing hoppers forcement, mineral from those used for other materials and on a scale of
admixtures aggregateshallbecapableofreceiving their appropriate sensitivity, measurement being taken from
rated load,without theweighed material coming into azeroreading. Aggregates shallbemeasured bymass,
contact with the loading mechanism. Where therated allowance being made forthe free moisture content of
capacity ofabatching plant mixing cycle is lessthan theaggregates. The added water shallbemeasured by
2.0 m3,additional precautions shall betaken toensure volume or by mass. Any liquid chemical admixture
that the correct number of batches are loaded intothe (orpaste) shallbemeasured byvolume orbymass and
truckmixer. Theweighinghoppersshallbeconstructed anysolidadmixturebymass. Whenweighingmaterials,
soastodischarge efficiently and prevent the build up anybuildupinthehopper during thedaymustbetared
of materials. A tare adjustment, upto 10percent of out or allowed for in the batch weights. After
the nominal capacity of the weigh scale, shall be measurement allmaterials shall bedischarged intothe
provided ontheweighing mechanism sothatthescale mixer without loss.
can be adjusted to zero at least once each day. Dust
seals shall be provided on cement hoppers between The accuracy of the measuring equipment shall be
the loading mechanism and the weigh hopper, and within*2percentofthequantity ofcement andmineral
shall be fitted so asto prevent the emission of cement admixtures being measured and within + 3percent of
dustand notto affect weighing accuracy. The hopper the quantity of aggregate, chemical admixture and
shallbeventedtopermit escapeofairwithout emission water being measured. The plant operator shall be “
of cement dust. provided with a clear display of the quantities of
materials tobebatched foreachmix andbatch sizeand
Vibrators or other attachments, where fitted, shall not
with information identi~ing the display to beselected
affect the accuracy of weighing. There shall be
for eachdesigned and prescribed mix to beproduced.
sufficient protection to cement and aggregate weigh
Analogue scale displays for the weighing of cement,
hoppers and weighing mechanisms to prevent
mineral admixtures, aggregates and water shall be
interference with weighing accuracy by weather
readily discemable from the operating position. For
conditions or external build-up ofmaterials.
digital readouts the numerals shall be readily
Where chemical admixture dispensers are used, they discernible from the operating position.
shall becapable ofmeasurement within thetolerances
Fully automatic production systems shall be fitted
inAnnex E and acalibrated container orweigh scales
with control equipment to allow the correct operation
shallbeprovidedtochecktheaccuracyofmeasurement
of the plant to be monitored during weighing and
at leastonce amonth.
batching. Automatic control systemsonbatching plants
Whereacontinuous mixer with ribbon loading isused, shallnotcommencebatchinguntilallhoppershavebeen
the batching procedure specified by the manufacturer emptied and/or tared andthe scaleszeroed unless such
ofthe plant shall be followed. systems are designed to take account of build up in
their programming.
Each control on the batching console and weigh-dial

or display shall be clearly labelled with its function All scales shall be tested and calibrated as per
and where concerned with the batching of materials, Annex E.
the material type.
9.1.4 Mixing
When more than onetype orgrade of cement isbeing
used,theweighing device anddischarge screworother 9.1.4.1 Washing out water
parts of the transfer system shall be empty before
changing from one type of cement to another. Before loading concrete materials or mixed concrete
intoeither astationary mixer ortruck mixer any water
Whenpulverized fuelashandothermineral admixtures retained inthe mixing drum for washing out purposes
are batched through the cement weigh system, the shall becompletely discharged.
weighing device and discharge screw orother parts of
thetransfer system shall be empty when the weighing 9.1.4.2 Stationa~ or central mixers
system has returned to zero reading or completed the
batch. Stationary mixers shall not be loaded inexcess of the
manufacturer’s rated capacity. The mixing time shall
Where a backweigh system is utilized to weigh be measured from the time all the materials required
materials a system shall be in place so as to prevent for the batch, including water, are in the drum of the
materials being loaded duringtheprocessofweighing. mixer. The mixing time shall not be less than that
recommended bythemanufacturer. Whereacontinuous
9.1.3 Measuret72ent of Materials
mixing plant isusedthecomplete mixing time shallbe
Cement and mineral admixmre materials shall be sufficient toensure that the concrete isofthe required
measured bymass inahopperorcompartment separat e uniformity.
5