Rebar Locator Test
IS: 456-2000
FOREWORD
ThisIndianStandard (Fourth Revision) wasadopted bytheBureau ofIndian Standards, afterthedraftfinalized
. by theCementandConcrete SectionalCommittee hadbeenapproved by theCivilEngineering Division Council.
This standardwas firstpublished in 1953 underthe title 'Codeof practice forplainandreinforced concrete for
general buildingconstruction' and subsequently revised in 1957. The code was further revised in 1964 and
published undermodified title 'Code of practice forplainandreinforced concrete',thusenlarging the scopeof
useof thiscodeto structures otherthangeneral building construction also. Thethirdrevision was published in
1978, and it includedlimit state approach to design. This is the fourth revision of the standard. Thisrevision
wastakenup witha viewto keeping abreast withtherapiddevelopment in thefieldof concrete technology and
to bringin furthermodifications/improvements in thelightofexperience gained whileusingtheearlierversion
of the standard.
Thisrevision incorporates a number of important changes. Themajorthrustin the revision is on the following
lines:
a) In recent years. durability of concrete structures have become the cause of concern to all concrete
technologists. This has ledto the needto codify thedurability requirements worldover. In thisrevision
of the code. in orderto introduce in-built protection from factors affecting a structure, earlierclauseon
durability has been elaborated and a detailed clause covering different aspects of design of durable
structure has been incorporated.
b) Sampling and acceptance criteriafor concrete havebeenrevised. With thisrevision acceptance criteria
has been simplified in line with the provisions given in BS 5328 (P8l1 4):1990 'Concrete: Part 4
Specification for the procedures to be usedin sampling, testing and assessing compliance of concrete'.
Someof the significant changes incorporated in Section 2 are asfollows:
a) All the threegradesof ordinary Portland cement, namely 33 grade, 43 gradeand 53 gradeand sulphate
resisting Portland cement have been included in the list of types of cementused (in addition to other
types of cement).
b) Thepermissible limits forsolids inwaterhavebeen modified keeping inviewthedurability requirements.
c) The clause on admixtures has been modified in view of the availability of new types of admixtures
including superplasticizers.
d) In Table2 'Grades of Concrete', grades higherthanM 40 havebeen included.
e) It has been recommended that minimum grade of concrete shall be not less than M 20 in reinforced
concrete work (see also6.1.3).
f) The formula for estimation of modulus of elasticity of concrete has beenrevised.
g) In the absence of proper correlation between compacting factor, vee-bee time and slump,workability
has now been specified only in termsofslump in line withthe provisions in BS 5328(Parts 1 to 4).
h) Durability clausehasbeenenlarged toinclude detailed guidance concerning thefactors affecting durability.
The table on 'Environmental Exposure Conditions' has been modified to include 'very severe' and
'extreme' exposure conditions. This clause also covers requirements for shape and size of member,
depthofconcrete cover, concrete quality, requirement against exposure toaggressive chemical andsulphate
attack,minimum cementrequirement andmaximum watercementratio,limitsof chloride content. alkali
silica reaction, and importance of compaction, finishing andcuring.
j) Aclauseon-'Quality Assurance Measures' hasbeen incorporated to givedue emphasis to goodpractices
of concreting.
k) Properlimitshavebeenintroduced ontheaccuracy of measuring equipmentstoensureaccurate batching
of concrete.
1 SCOPE
1.1 This standard deals with the generalstructuraluse
of plain and reinforced concrete.
1.1.1 For the purpose of this standard, plain concrete
structures are those where reinforcement,if provided
is ignoredfordetermination of strengthof thestructure.
1.2 Special requirementsof structures,such as shells,
folded plates,arches.bridges,chimneys,blastresistant
structures, hydraulic structures, liquid retaining
structuresand earthquakeresistantstructures,covered
in respective standards have not been covered in this
standard; these standards shall be used in.conjunction
with this standard
2 REFERENCES
The Indian Standards listed in Annex A contain provisions which through reference in this text, constitute provisions of thil standard. At the time of publication, the edition. indicated were valid. All standards are subject to revision and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated in AnnexA.
3 TERMINOLOGY
For the purpose of this standard, the definitions Biven in IS 4845 and IS 6461 (Parts 1 to 12) shall generally apply
5 MATERIALS
s.t Cement
The cement used shall he any of the following and the
type selected should be appropriate for the intended
use:
a) 33 Grade ordinary Portland cement
conforming to IS 269
b) 43 Grade ordinary Portland cement
conforming to IS 8112
c) S3 Grade ordinary Portland cement
conforming to IS 12269
d) Rapid hardening Portlandcement conforming
to IS 8041
e) Portland slag cement conforming to IS 4;5
f) Portland pozzolana cement (fly ash based)
conforming to IS 1489 (Part 1)
g) Portland pozzolana cement (calcined clay
based) conforming to IS 1489 (Part 2)
h) Hydrophobic cement conforming to IS 8043
j) Low heat Portland cement conforming to
IS 12600
k) Sulphate resisting Portland cement
conforming to IS 12330
Other combinations of Portland cement with mineral
admixtures (see $.2) of quality conforming with
relevant Indian Standards laid down may also be used
in the manufacture of concrete provided that there are
satisfactory dati on their suitability, such as
performance test concrete containing them.
5.1.1 Low heat Portland cement conforming to
IS 12600 shall be usedwith adequateprecautionswith
regard to removal of formwork, etc.
5.1.Z Hiah alumina cement conforming to IS 6452 or
supersulphated cement conforming to IS 6909may be
used only under special circumstances with the prior
approval of the engineer-in-charge. Specialistliterature
Inay be consuIted for guidance regarding the use of
these types of cements.
5.1.3 The attention of the engineers-in-charge and
users of cement is drawn to the fact that quality of
various cements mentioned in 5.1 is to be determined
on the basis of its conformity to the performance
characteristics given in the respective Indian Standard
Specification forthatcement. Any trade-mark or any
trade nameindicating any special features not covered
in. the standard or any qualification or other special
performance characteristics sometimes claimedl
indicatedon the bass or containersor in advertisements
alongside the 'Statutory QualityMarking' or otherwise
6 CONCRETE
6.1 Grades
The concrete shall be in grades designated as per
Tanlc 2
6.1.1 The characteristic strength is defined as the
strength of material below which not more than
5 percent of the test results arc expected to fall.
6.1.2 Tile minimum grade of concrete for plain and
reinforced concrete shall be as per Table 5.
6.1.3 Concrete of grades lower than those given in
Table 5 may he used for plain concrete constructions.
lean concrete, SImple foundations, foundation for
masonry walls and other simple or tcmporury
reinforced concrete construction.
6.2 Properties of Concrete
6.2.1 IIIClI'(/.I'(, ofStrength with Agi'
There is normally a gain of strength beyond 2S days.
The quantum of increase depends upon the )!radc and
type of cement, curing and cnvuoruucnral conditions,
etc. The design should 1)(' h:1S,xl on 2x dav-, charactcristic strength "fcom.r. " 'lIlkss there is a evidence III
justifya higherstrength fora particularstructure dueto
age.
6.2.1.1 For concrete of grade M 30 and above. the
rateofincrease of compressive strength withageshall
be basedon actualinvestigations.
6.2.1.2 Where members are subjected to lowerdirect
loadduringconstruction, they should be checkedfor
stresses resulting from combination of directloadand
bending duringconstruction.
6.2.2 Tensile Strength of Concrete
The flexural and splitting tensile strengthsshall be
obtained as described in IS 516 and IS 5816
respectively. When the designer wishes to use an
estimateof the tensilestrength fromthe compressive
strength, the following formula may be used: