IS :516 -1959

( Reaffirmed 1999 )
Indian Standard
METHODS OF TESTS FOR
STRENGTH OF CONCRETE

Fifteenth Reprint AUGUST 1993

( Incorporating Amendment No. 1)

UDC 66697 : 62017

0 Copyright 1975

BUREAU OF INDIAN STANDARDS

MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARC3
NEW DELHI-I 10002

GE 6 December 1959
 \

IS : 516 - 1959

hdian Standard
METHODS OF TESTS FOR
STRENGTH OF CONCRETE

Cement and Concrete Sectional Committee, BDC 2

Clbairmqn
SHRI E. A. NADIRSHAH The Concrete Xssociation of India, Bombay, and
the Institution of Engineers ( India ). Calcutta

Members
SHR: BALESHWAR N.~TH Central Board of Irrigation C Power ( Vi&try ol
Irrigation C Power)
SHRI N. H. BHAGWANANI Engineer-in-Chiefs Branch, Army Headquarters
&RI N. D. DAFTARY Bombay State Road Transport Corporation, Bombay
SHRI P. I,. Das Directorate tiencral of Supplies & Disposals
(blinistry of Works, Houding & Supply )
0lRECTOR Central Building Research Institute ( CSIR ),
Roorker
SWRI C. H. KH_~DILKAR( Alternate)
SHXI C: L. HasDA Directorate of Designs, Bhnkra Dam, Sew Delhi
SHRI P. S. BHATPIAGAR( Allernnte )
The .\ssociatcd Cement Companies Ltd, Bomba\.
DR ~R~i%?~;DWZd~ )
SHRI P. C. HAZR+ Geological S rvev of India, Calcutta
L;)R I?. C. 1100x Central Wat 7r Ji- Iower Commission ( .\iinistrv 01
Irrigation & Pou er )
SHRI GEORGE 00~~65 ( Ahwafc: )
SHRI S. B. J~SHI S. B. Joshi d Co, Bomba)
SHR~ S. R. JIEHKA Central Road Research Institute ( CSIK ), Nev
Delhi
SHRI S. N. >IUKERJI Government Test House, Calcutta
SHRL K. Ii. CHATTERJEE (Alia7ude)
SHPJ E. 1. NUJOL.W~ES Gammon India Ltd, Bombay. u,ad Indian Road>
Congress. New Delhi
t<BPRESENTATIVE Martin Bum Ltd, Calcutta
SHRI J. M. lQ.i~w.4~1 Central Public Works ljcpartment
SHHI M. S. BHATIA ( Altwwle)
SHKI NI~\R CHAN~RA Roy Dalmia Cemem ( Bharat ) Ltd, Calcutta
SI~R! .4. Ii. CHAKRAVARTL f Altermte: )
SHRI SAIWP SIXGIl National Buildmgs Organisatiou ( Ministry of
Works, Housing h Supply \
DEPUTY DIKECIOR ( 31.4~5~14~ ) ( Al!ernufe )
( Corztinued on page 2 )

BUREAU OF INDIAN STANDARDS

MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR hIARG
NEW DELHI 110002
IS : 516 - 1959

{ Continued from page 1)

SHRI H. P. SINMA Roads Wing, Ministry of Transport C Commnrnca-

tions
SHR~ J. XI. TREHAX I A&--mule)
SHR~ Ii. C. Soon Research, Design C Standardization Organization
( Ministry of Railways j
SHKI S. S. KARMA (_4ltern&)
L)R IAL C. VRRXAN f Ew-ojkio ) Director, Indian Standards Institution

Deputy Director ( Bldg )+ lndisn Standards Iasti-

tution

Subcommittee, BDC 2: 2

S. H. Joshi 8: Co, Bomba!.

The Associated Cement Companies Ltd., Bombay

Engineer-in-Chiefs Branch, Army Headquarters
Central Public Works Department
SNRI T. S. \ri~~)~G~~i ( .4llernate)
ti1nEcr0~ Engineering Research Laboratories, Hyderabad
SHRI I. C. HAZRA Geological Survey of India, Calcutta
DR 1~. C.. Hoos Central Water & Power Commission (Ministry of
Irrigation & Power)
SHRL C. L. S. IYEHGAH The Concrete Association of India, Bombay
SHRI S. \I. NATU Public Works Department, Bombay
SHRI C. C. P.*TEL ( .4/trr,fnte)
SHRI E. I. Nrco~arn~s Gammon India Ltd., Bombay
DR K. L. RAO Central Water L Power Commission (Ministry of
Irrigation & Power )
SHRI SAR~W SlHGH National Buildings Organisation ( Ministry of
Works, Housing & Supply \
SHRI K. RAMA V.MMAN ( Altevnafc)
SHRI H. P. SlSHA Roads Wing, Ministry of Transport & Communica-
tions
SHRI Ii. c. SOOn Research, Design & Standardiiation Organization
( Ministry of Railways )

2
 IS : 516 - 1959

Indian Standard
METHODS OF TESTS FOR
STRENGTH OF CONCRETE
0. FOREWORD
0.1 This Indian Standard was adopted by the Indian Standards Institution
on 10 November 1959, after the draft finalized by the Cement and
Concrete Sectional Committee had been approved by the Building Division
Counci!.
0.2 Testing plays an important role in controlling the quality of cement
concrete work. Systematic testing of the raw materials, the fresh con-
crete and the hardened concrete is an inseparable part ,of any quality
control programme for concrete which helps to achieve higher efficiency
of the materials used and greater assurance of the performance of the
concrete in regard to both strength and durability. The test methods
used should be simple, direct and convenient to apply. This standard
has been prepared with this object in view and provides a guide to the
determination of compressive strength, fleirural strength and modulus of
elasticity of concrete. Sampling and analysis of concrete have been covered
separately in IS : 1199-1959 Methods of Sampling and Analysis of Concrete.
0.3 The Sectional Committee responsible for the preparation of this stan-
dard has taken into consideration the views of concrete specialists, testing
authorities, consumers and technologists and has related the standard to
the practices followed in the country in this field. The need for inter-
national co-ordination between standards prevailing in different countries
of the world has also been recognized. These considerations led the Sec-
tional Committee to derive assistance from the published standards and
public&tions of the following organizations:
BRITISHSTANDARDS INSTITUTION
AMERICANSOCIETYFORTESTINGMAT$RIAU
AMERICANCONCRETE INSTITUTE
CANADIANENGINEERING STANDARDS ASWUATION
RESEARCH,DESIGN & STANDARDIZATION ORGANIZATION, MINISTRY
OF RAILWAYS,GOVERNMENT OF INDIA
THE CONCRETE ASSOCIATION OF INDIA
0.4 The Indian Standard Methods of Sampling and Analysis of Concrete
( IS: 1199-1959) is a necessary adjunct to this standard. Besides, this
standard requires reference to the following Indian Standards:
*IS : 269-1958 SPECIFICATION FOR ORDINARY,RAPID-HARDENING AND
Low HEAT PORTLAND CEMENT(Revised)
*Since revised.
3
IS : 516 - 1959

IS : 383-1952 SPECIFICATION
FORCOARSEAND FINE AGGREGATESFROM
NATURAL SWRCES FOR CONCRETE
tIS : 455-1953 SPECIFICATIONFOR, PORTLAND BLASTFURNACE SLAG
CEMENT
SIS : 456-1957 CODE OF PRACTICEFOR PLAIN AND REINFORCEDCON-
CRETE FOR GENERAL BUILDING CONSTRUCTION (Kevised)
*IS : 460-1953 SPECIFICATIOX
FOR Tesr SIEVES
0.4.1 Wherever a reference to any standard mentioned in 0.4, except
IS: 460-1953, appears in this standard, it shall be taken as a reference to
the latest version of the standard.
0.5 In pursuance of the decision of the Government of India to introduce
a uniform system of weights and measures throughout the country based
on the metric system, in this standard, ali dimensions and values have
been given in metric units only. It is hoped that this step will facilitate
the change-over to the metric system by the industry more expeditiously.
0.6 For the purpose of deciding whether a particular requirement of this
standard is complied with, the final value observed or calculated, expres-
sing the result of a test or analysis, shall be rounded off in accordance
with*IS: 2-1943 Rules for Rounding Off Numerical Values. The number
of significant places retained in the rounded off value should be the same
as that of the specified value in this standard.
8.7 This standard is intended chiefly to cover the technical provisions
relating to the testing of concrete, and it does not include all the necessary
provisions of a contract.

1. SCOPE

1.1 This standard covers tests for the determination of compressive

strength, flexural strength and modulus of elasticity of cement concrete.

2. MAKING AND CURING COMPRESSION

TEST SPECIMENS IN THE LABORATORY

2.1 This clause specifies the procedure for making and curing compression
test specimens of concrete in the laboratory where accurate control of the
quantities Qf m&trials and test conditions are possible and where the
maximum nfJmind size of aggregate does not exceed 38 mm. The method
is specially applicable to the making of preliminary compression tests
to ascertain the suitability of the avaiiable materials or to determine
suitable mix proportions.
2.2 Sampling of Materialo .-- Hepresentative samples of the materials
of concrete for use in the particular concrete construction work shall be
lSince revised.
i Second wvision issued in 1967. 4
Second revision issued In 19M.
 IS: 516 - 1959

obtained by careful sampling. Test samples of cement shall be made up

of a small portion taken from each of a number of bags on the site. Test .
samples of aggregate shall be taken from larger lots by quartering.
2.3 Preparation of Materials -All materials shall be brought to room
temperature, preferably 27 + 3% before commencing the tests.
The cement samples, on arrival at the laboratory, shall be thoroughly
mixed dry either by hand or in a suitable miser in such a manner as to
ensure the greatest possible blending and uniformity in the material, care
being taken to avoid the intrusion of foreign matter. The cement shall
then be stored in a dry place, preferably in air-tight metal containers.
Samples of aggregates for each batch of concrete shall be of the desired
grading and shall be in an air-dried condition. In general, the aggregate
shall be separated into fine and coarse fracticns and recombined. for eacll
concrete batch in such a manner as to produce the desired grading IS
Sieve 480 shall be normally used for separating the fine and coarse frac-
tions, but where special gradings are being investigated, both tine and
coarse fractions shall be further separated into different sizes.
2.4 Proportioning - The proportions of the materials, including water,
in concrete mixes used for determining the suitability of the materials
available shall be similar in all respects to those to be employed in the
.Arork. Where the proportions of the ingredients of the concrete as used
m the site are to be specified by volume, they shall be calculated from
the proportions by w.eight used in the test cubes and the unit wciphts of
the materials.
2.5 Weighing -The quantities of cement, each size of aggregate, and
water for each batch shall be determined by weight, to an accuracy of
O-1 percent of the total weight of the batch.
2.6 Mixing Concrete - The concrete shall be mised by hand, cr pre-
ferably, in a laboratory batch mixer, in such a manner as to avoid loss of
water or other materials. Each batch of concrete shall bc of such a ~1~1:
as to leave about 10 percent excess after rnoulding the desired number of
test specimens.
2.6.1 Mnckine Mixing -When the mising drum is charged by a power
loader, all the mixing water shall be introduced jnto the drum before the
solid materials; the skip shall be loaded with about one-half of the coarse
aggregate, then with the fine aggregate, then with the cement and finally
with the remaining coarse aggregate on top. (If alI-in-aggregate is used,
the skip shall be loaded first with about one-half of the aggregate. then
with the cement and finally with the remaining aggregate on toI>.)
Where the mising drum is hand-loaded it shall be charged with the dry
materials in a similar manner, and the water shall be added immedi&cJy
before the .rotation of the drum is started. The period of mixing shall

5
 IS : 516 - 1959

be not less than 2 minutes after all the materials are iu the drum, and shall
continue till the resulting concrete is uniform in appearance. When using
pan mixers, the concrete shall be heaped together before sampling.
2.6.2 Hand Mixing-The concrete batch shall be mixed on a water-
tight, non-absorbent platform with a shovel, trowel or similar suitable
implement, using the following procedure :
a) The cement and fine aggregate shall be mixed dry until the mixture
is thoroughly blended and is uniform in colour,
b) The coarse dggregate shall then be added and mixed with the
cement and fine aggregate until the coarse aggregate is uniformly
distributed throughout the batch, and
c) The ,water shall then be added and the entire batch mixed until
the concrete appears to be homogeneous and has the desired con-
sistency. If repeated mixing is necessary, because of the addition
of water in increments while adjusting the consistency, the batch
shall be discarded and a fresh batch made without interrupting
the mixing to make trial consistency tests.
2.7 Workability - Each batch of concrete shall be tested for consistency
immediately after mixing, by one of the methods described in IS:
1199-1959. Provided that care is taken to ensure that no water or other
material is lost, the concrete used for the consistency tests may be re-
mixed with the remainder of batch before making the test specimens.
The period of re-mixing shall be as short as possible yet sufficient to produce
a homogeneous mass.
2.8 Size of Test Specimens - Test specimens cubical in shape shall be
15 x 15 x 15 cm. If the largest nominal size of the aggregate doesnot
exceed 2 cm, 10 cm cubes may be used as an alternative. Cylindrical test
specimens shall have a length equal to twice the diameter. They shall
be 15 cm in diameter and 30 cm long. Smaller test specimens shall have
a ratio of diameter of specimen to maximum size of aggregate of not less
than 3 to 1, except that the diameter of the specimen shall be not less
than 7.5 cm for mixtures containing aggregate more than 5 percent of
which is retained on IS Sieve 480.

2.9 Moulds
2 9.1 Cube Moulds -The mould shall be of metal, preferably steel or
cast iron, and stout enough to prevent distortion. It shall be constructed
in such a manner as to facilitate the removal of the moulded specimen
without damage, and shall be SC lnachined that, when it is assembled ready
for use, the dimensions and internal faces shall be accurate within the
following limits :
The height of the mould and the distance between opposite faces
shall be the specified size f 0.2 mm. The angle between adjacent

6
 IS: 516 - 1959

internal faces and between internal faces and top and bottom planes
of the mould shall be 90 iO.5. The interior faces of the mould
shall be plane surfaces with a permissible variation of 0.03 mm.
Each mould shall be provided with a metal base plate having a plane
surface. The base plate shall be of such dimensions as to support
the mould during the filling without leakage and it shall be preferably
attached to the mould by springs or screws. The parts of the mould
when assembled shall be positively and rigidly held together, and
suitable methods of ensuring this, both during the filling and on
subsequent handling of the filled mould, shall be provided.
2.9.1.1 In assembling the mould for use, the joints between the
sections of mould shall be thinly coated with mould oil and a similar
coating of mould oil shall be applied between the contact surfaces of the
bottom of the mould and the base plate in order to ensure that no water
escapes during the filling. The interior surfaces of the assembled mould
shall be thinly coated with mould oil to prevent adhesion of the concrete.

2.9.2 Cyliltders - The cylindrical mould shall be of metal which shall

be not less than 3 mm thick. Each mould shall be capable of being opened
longitudinally to facilitate removal of the specimen and shall be provided
with a means of keeping it closed while in use. The ends shall not depart
from a plane surface, perpendicular to the axis of the mould, by more than
0.05 mm. When assembled ready for use, the mean internal diameter of
the mould shall be 15.0 cm + 0.2 mm and in no direction shall the internal
diameter be less than 14.95 cm or more than 15.05 cm. The height shall
be 30.0 cm -10.1 cm. Each mould shall be provided with a metal base
plate, and &h a capping plate of glass or other suitable material. The
base plate and the capping plate shall be at least 6.5 mm thick, and such
that they do not depart from a plane surface by more than 0.02 mm.
The base plate shall support the mould during filling without leakage and
shall be rigidly attached to the mould. The mould and base plate shall
be coated with a thin film of mould oil before use, in order to prevent
adhesion of the concrete.

2.9.3 Tumpilg Bar - The tamping bar shall be a steel bar 16 mm in

diameter, 0.6 m long and bullet pointed at the lower end.

2.10 Compacting - The test specimens shall be made as soon as prac-

ticable after mixing, and in such a way as to produce full compaction of
the concrete with ncithcr segregation nor excessive laitance. The con-
crete shall be filled into the mould in layers approximately 5 cm deep.
In placing each scoopful of concrete, the scoop shall be moved around the
top edge ot the mould as the coucrete slides from it, m order to ensure R
symmetrical distribution of the concrctc within the mould. Each layer
shall be compacted either by hand or by vibration as described below
(see 2.10.1 ad 2.10.2). After the top layer has been compacted, the

7
 IS: 516 - 1959

surface of the concrete shall he finished level with the top of the mould,
using a trowel, and covered with a glass or metal plate to prevent
evaporation.
2.10.1 Compacting by Hand-When compacting by hand, the stan-
dard tamping bar shall be used and the strokes of the bar shall he distri-
buted in *a uniform manner over the cross-section of the mould. The
number of strokes per layer required to produce specified, conditions will
vary according to the type of concrete. For cubical specimens, in no
case shall the concrete be subjected to less than 35 strokes per layer for
15 cm cubes or 25 strokes per layer for 10 cm cubes. For cylindrical speci-
mens, the number of strokes shall not be less than thirty per layer. The
strokes shall penetrate into the underlying layer and the bottom layer
shall be rodded throughout its depth. Where voids are left by the tamp-
ing bar, the sides of the mould shall be tapped to close the voids.
2.10.2 Compacting by Vibration -When compacting by vibration, each
layer shall be vibrated by mep,ns of an electric or pneumatic hammer or
vibrator or by means of a suitable vibrating table until the specified con-
dition is attained.
NOTE -- The mode and quantum of vibration of the laboratory specimen shall
be as nearly the same as those adopted in actual concreting operations.

2.11 Capping Specimens -The ends of all cylindrical test specimens

that are not plane within 0.05 mm shall be capped. Capped surfaces
shall not depart from a plane by more than 0.05 mm and shall be approxi-
mately at right angles to the axis of the specimens. The planeness of the
cap shall be checked by means of a straight edge and feeler gauge, making
a minimum of three measurements on different diameters. Caps shall be-
made as thin as practicable and shall not flow or fracture when the specimen
is tested. Capping shall be carried out according to one of the following
methods.
2.11.1 Neat Cement - Test cylinders may be capped with a thin layer
of stiff, neat Portland cement paste after the concrete has ceased settling
in the moulds, generally for two to four hours or more after moulding.
The cap shall be formed by means of glass plate not less than.6.5, mm in
thickness or a machined metal plate not less than 13 mm in thickness and
having a minimum surface dimension at least 25 mm larger than the dia-
meter of the mould. It shall be worked on the cement paste until its
lower surface rests on the top of the mould. The cement for capping shall
be mixed to a stiff paste for about two to four hours before it is to be
used in order to avoid the tendency of the cap to shrink. Adhesion of
paste to the capping plate may be avoided by coating the plate with a
thin coat of oil or grease.
2.11.2 Szd/ht~ - *Just prior to testing, the cylindrical specimens mav be
capped with a sulphur mixture consisting of 2 or 3 parts sulphur to 1 part
of inert filler, such as tire-clay. . The specimens shall be securely held m a

8
 IS: 516 - 1959

special jig so that the caps formed have true plane surfaces. Care shall be
taken to ensure that the sulphur compound is not over-heated as it will
not then develop the required compressive strength. Sulphur caps shall be
allowed to harden for at least 2 hours before applying the load.
2.11.3 Hard Plaster - Just prior to testing, specimens may be capped
with hard plaster having a compressive strength of at least 420 kg/sq cm
in one hour. Such plasters are generally available as proprietory material.
The cap shall be formed by means of a glass plate not less than 13 mm in
thickness, having a minimum surface dimension at least 25 mm larger than
the diameter of the mould. The glass plate shall be lightly coated with
oil to avoid sticking.
Nore .--. Ordinary plaster of park will not serve the purpose of the capping
materia! due to its low compressive strength.

2.11.4 As soon as possible after the concrete is mixed, a mortar shall

be gauged using a cement similar to that used in the concrete and sand
which passes IS Sieve 30 but is retained on IS Sieve 15. The mortar shall
have a water/cement ratio not higher than that of the concrete of which
the specimen is made, and shall be of a stiff consistence. If an excessively
wet mix of concrete is being tested, any free water which has collected
on the surface of the specimen shall be removed with a sponge, blotting
paper or other suitable absorbent material before the cap is formed. The
mortar shall then be applied firmly and compacted with a trowel to a
slightly convex surface above the edges of the mould, after which the
capping plate shall be pressed down on the cap with a rotary motion until
it makes complete contact with the rim of the mould. The plate shall
be left in position until the specimen is removed from the mould.
2.12 Curing - The test specimens shall be stored in a place, free from
vibration, in moist air of at least 90 percent relative humidity and at a
temperature of 27 $ 2C for 24 hours + 4 hour from the time of addition
of water to the dry ingredients. After this period, the specimens shall be
marked and removed from the moulds and, unless required for test withiu
24 hours, immediately submerged in clean, fresh water or saturated lime
solution and kept there until taken out just prior to test. The water or
solution in which the specimens are submerged shall be renewed every
seven days and shall bc maintained at a temperature of 27 + 2C. The
specimens shall not be alloweo to become dry, at any time until they have
been tested.

3. MAKING AND CURING COMPRESSION TEST

SPECIMEN IN THE FIELD

3.1 This clause deals with the procedure for making and curing compres-
sion test specimens of concrete sampled during the progress of construction
where the nominal maximum size of the aggregate does not exceed 38 mm.

9
IS : 516 - 1959

3.2 Size of test specimen, apparatus to be used and procedure to prepare

specimens shall be the same as specified in 2:
3.3 Curing -The test specimens shall be stored on the site at a place
free from vibration, under damp matting, sacks or other similar material
for 24 hours + 4 hour from the time of adding the water to the other
ingredients. The temperature of the place of storage shall be within the
range of 22 to 32C. After the period of 24 hours, they shall be marked
for later identification, removed from the moulds and, unless required for
testing within 24 hours, stored in clean water at a temperature of 24 to
30C until they are transported to the testing laboratory. They shall be
sent to the testing laboratory well packed in damp sand, damp sacks, or
other suitable material so as to arrive there in a damp condition not less
than 24 hours before the time of test. On arrival at the testing laboratory,
the specimens shall be stored in water at a temperature of 27 + 2C until
the time of test. Records of the daily maximum and minimum tempe-
rature shall be kept both during the period of the specimens remain on
the site and in the laboratory.

4. SECURING AND PREPARING SPECIMENS OF

HARDENED CONCRETE FOR COMPRESSION TEST

4.1 This clause deals with the procedure for securing and preparing corn--
pression test specimens obtained from hardened concrete after the wn-
Crete has been laid in position.
4.2 The test specimens shail be procured from hardened concrete according
to the method described in 4 of IS: 1199-1959.

4.3 Cores to be tested for compression strength shall have ends that are
reasonably even, perpendicular to the axis and of the same diameter as
the body of the specimen. A core which, before capping, has a maximum
height of less than 95 percent of the diameter, or after capping, a height
less than its diameter shall not be used.
4.4 Capping -The ends of the specimen shall be capped before testing.
The material used for the capping shall be such that its compressive
strength is greater than that of the concrete in the core. Caps shall be
made as thin as practicable and shall not flow or fracture hefore the con-
crete fails when the specimen is tested. The capped surfaces shall be at
right angles to the axis of the specimen and shall not depart from a plane
by more than 0.05 mm. The capping of specimens shall be carried out
as described in 2.11.
4.5 After checking for irregularities, the core shall be placed in water at a
temperature of 24 to 30C for 48 hours before testing. The overall height
of the specimens, with capping shall be measured to the nearest millimetre.
*Since revised.
10
 IS: 516 - 1959

5. TEST FOR COMPRESSIVE STRENGTH OF

CONCRETE SPECIMEN

5.1 This clause deals with the procedure for determining the compressive
strength of concrete specimens.

5.2 Apparatus
5.2.1 Testing Machine - The testing machine may be of any reliable
type, of sufficient capacity for the tests and capable of applying the load
at the rate specified in 5.5. The permissible error shall be not greater
than +- 2 percent of the maximum load. The testing machine shall be
equipped with two steel bearing platens with hardened faces. One of the
platens (preferably the one that normally will bear on the upper surface
of the specimen) shall be fitted with a ball seating in the form of a portion
of a sphere, the centre of which coincides with the central point of the
face of the platen. The other compression platen shall be plain rigid
bearing block. The bearing faces of both platens shall be at least as large
as, and preferably larger than the nominal size of the specimen to which
the load is applied. The bearing surface of the platens, when new, shall
not depart from a plane by more than 0.01 mm at any point, and they
shall be maintained with a permissible variation limit of 0.02 mm. The
movable portion of the spherically seated compression platen shall be held
on the sphericaI seat, but the design shall be such that the bearing face
can be rotated freely and tilted through small angles in any direction.
5.3 Age at Teat -Tests shall be made at recognized ages of the test
specimens, the most usual being 7 and 28 days. Ages of 13 weeks and one
year are recommended if tests at greater ages are required. Where it may
be necessary to obtain the early strengths, tests may be made at the ages
of 24 hours + ) hour and 72 hours + 2 hours. The ages shall be cal-
c&ted from the time of the addition of water to the dry ingredients.
5.4 Number of Specimens -At least three specimens, preferably from
different batches, shall be made for testing at each se3ected age.
NOTE - When a full investigation is being carried out, it is advisable for three
separate batches to be made for each given variable. An equal number of speci-
mens for each variable should be made.

5.5 Procedure -Specimens stored in water shah be tested immediately

on removal from the water and while they are still in the wet condition.
Surface water and grit shall be wiped off the specimens and any projecting
fins removed. Specimens when received dry shall be kept in water for
24 hours before they are taken for testing. The dimensions of the speci-
mens to the nearest 0.2 mm and their weight shall be noted before testing.
5.5.1 Placing the S+&acn in the Testing Machine - The bearing surfaces
of the testing machine shall be wiped clean and any loose sand or other
material removed from the surfaces of the specimen which are to be in

11
IS: 516 - 1959

contact with the compression platens. In the case of cubes, the specimen
shall be placed in the machine in such a manner that the load shall be ap-
plied to opposite sides of the cubes as cast, that is, not to the top and
bottom. The axis of the specimen shall be carefully aligned with the
centre of thrust of the spherically seated platen. No packing shall be
used between the faces of the test specimen and the steel platen of the
testing machine. As the spherically seated block is brought to bear on
the specimen, the movable portion shall be rotated gently by hand so
that uniform seating may be obtained. The load shall be applied without
shock and increased continuously at a rate of approximately 140 kg/sq
cm/min until the resistance of the specimen to the increasing load breaks
down and no greater load can be sustained. The maximum load applied
to the specimen shall then be recorded and the appearance of the concrete
and any unusual features in the type of failure shall be noted.
5.6 Calculation-The measured compressive strength of the specimen
shall be calculated by dividing the maximum load applied to the specimen
during the test by the cross-sectional area, calculated frog the mean di-
mensions of the section (see also 4.5.1 of IS: 1199-1959) and shall be
expressed to the nearest kg per sq cm. Average of three values shall be
taken as the representative of the batch provided the individual variation
is not more than f 15 percent of the average. Otherwise repeat tests
shah be made.
5.6.1 A correction factor according to the height/diameter ratio of
specimen after capping shall be obtained from the curve shown in Fig. 1.
The product of this correction factor and the mcasurcd compressive
strength shall be known as the corrected compressive strength, this being
the equivalent strength of a cylinder having a height/diameter ratio of two.
The equivalent cube strength of the concrete shall be determined by
multiplying the corrected cylinder strength by 514.
5.6.2 Report - The following information shall be included in the report
on each test specimen:
a) identification mark,
b) date of test,
c) age of specimen,
d) curing conditions, including date of manufacture of specimen in
the field,
e) weight of specimen,
f) dimensions of specimen,
g) cross-sectional area,
h) maximum load,
j) compressive strength, and
k) appearance of fractured faces of concrete and type of fracture,
if these are unnauiid.
!hx n%ised.

12
 FIG. 1 CORRRCTIOS P,\CTOR FOR HRIGIIT/DIA~~ETRR t(AT1c-J OF A Coxa

6. DETERMINATION OF COMPRESSIVE
STRENGTH OF CONCRETE USING PORTIONS OF
BEAMS BROKEN IN FLEXURE ( EQUIVALENT
CUBE METHOD )

6.1 This clause specifies the procedure for determining the compressive
strength of concrete using portions of beams broken in flexure as the test
specimens. The results obtained from this test are approximately equal to,
and on the average may be up to 5 percent greater than those obtained
by the test specified in 5.
NOTE -- For m&hod of making and testing llc*xort: test spcimt.ns. see 7.

6.2 Apparatus

6.2.1 Com$ression2esting Machine - The testing machine shallcomply

in all respects with the requirements of 5.2.1.
6.2.2 Bearing Plates - Two metal bearing plates not less than 6-5 mm
or more than 19 mm thick shall be provided. The plates shall be IO an
square for the beams 10 cm in depth and 15 cm square for the beams 15 cm
in depth with the surfaces machined to a permissible variation not
exceeding O-02 mm. The distance between the opposite edges shall be
the specified size + O-02 mm and the angle between the edges shall bt
90 f 04.

13
IS : 516 - 1959

6.3 Test Specimens-The length of the broken portions of the beams

selected for the compression test shall be at least 5 cm greater than the
depth of the beam and the broken portions shall be free from cracks,
chipped surfaces or other obvious defects within the length to be tested.
6.4 Procedure -During the interval between testing the specimens as
beams and testing the broken portions as cubes, the specimens shall be
stored in water at a temperature of 24 to 30C and shall be tested im-
mediately on removal from the water and while still in the wet condition.
6.4.1 Placing the Specimen in the Testing Machine - The bearing sur-
faces of the testing machine and the bearing plates shah be wiped clean
and any loose sand or other material shall be removed from the surfaces
of the specimen which are to be in contact with the bearing plates. The
specimen shall be placed between the bearing plates in such a manner
that the upper bearing plate is directly over the lower plate and the bear-
ing plates extend at least 25 mm from each end of the specimen. 4 device
which ensures the proper location of the upper plate with reference to the
lower plate is shown in Fig. 2. No packing shall be used between the
faces of the specimen and the bearing plates. The specimens shall be
tested with the moulded sides in contact with the plates. The load shall

13 mm CLEARANCE

LA-1
FIG. 2 DEVICE FOR ALIGNING BEARING PLATES

14
 f5 : 516 - 19s9

be applied without shock and increased continuously at a rate of a xi-

mately 140 kg/sq cm/min uiltil the resistance of the specimen to Tt e in-
creasing load breaks down and no greater load can be sustained. The
maximum load applied to the specimen shall then be recorded and the
appearance of the concreteand any unusual features in the type of failure
shall be noted.
6.5 Calculation -The equivalent cube strength of the specimen shall
bc cafculated by dividing the maximum load by the area of contact of
the bearing plates and shall be expressed to the nearest kg/sq cm.
6.6 Report - The following information shall be included in the report
on each specimen:
a) identification mark,
b) date of test,
c) age of specimen,
d) curing conditions,
e) nominal size of specimen.
f) maximum load,
g) equivalent cube strength, and
h) appearance of the concrete and type of fracture, if these are unusua1.

7. MAKING AND CURING FLEXURE TEST

SPECIMENS IN THE LABORATORY

7.1 This clause specifies the procedure for making and curing flexure test
specimens of concrete in the laboratory where accurate control of the
quantities of materials and test conditions is possible, provided the maxi-
mum nominal size of the aggregate does not exceed 38 mm. The method
is specially applicable to the making of preliminary flexure tests to ascerta@
the suitability of the available material or to determine suitable mrx
proportions.
7.2 Sampling of Material - Preparation of materials, proportions,
weighing, mixing of concrete shall be done in the same way as in the case
of making compression test specimens in the laboratory (SCC 2).
7.2 Slza of Specimena - The standard size shall be 15 x 15 x 70 cm.
Alternatively, if the largest nominal site of the aggregate does not exceed
19 mm, specimens 10 x 10 x 50 cm may be used.

7.4 Apparatus

7.4.1 The mould shall be of metal, preferably steel or cast iron and the
metal shall be of sufficient thickness to prevent spreading or warping.
The mould shall be constructed with the longer dimension horizontal and
in such a manner as to facilitate the removal of the moulded specimens

15
IS : 516 - 1959

without damage. The mould shall be LO machined that when assembled

ready for use the dimensions shall be accurate within the following limits:
a) The height of the mould shall be either 15.0 f O-005 cm or
10.0 f 0.005 cm, and the corresponding internal width of the
mould shall be 15.0 f 0.02 cm or 10.0 f 0.02 cm respectively.
The angle between the interior faces and the top and bottom
planes of the mould shall be 90 -Jr O-5. The internal surfaces of
the mould shall. be plane surfaces with a permissible variation of
0.02 mm in 15.0 cm and O-1 mm overall.
b) Each mould shall be provided with a metal base plate and two
loose top plates of 4.0~ O-6 cm cross-section and 5.0 cm longer than
the width of the mould. The base plate and top plate shall have
plane surfaces with a permissible variation of 0.05 mm. The base
plate shall support the mould without leakage during the filling,
and shall be rigidly attached to the mould.
c) The parts of the mould when assembled shall be positively and
rigidly held together, and suitable methods of ensuring this, both
during the filling and on subsequent handling of the filled mould,
shall be provided.
d) In assembling the mould for use, the joints between the sections
of the mould shall be thinly coated with mould oil and a similar
coating of mould oil shall be applied between the contact surfaces
of the bottom of the mould and the base plate in order to ensure
that no water escapes during the filling. The interior faces of the
assembled mould shall be thinly coated with mould oil to prevent
adhesion of the concrete.
7.4.2 Tamping Bar-The tamping bar shall be a steel bar weighing
2 kg, 40 cm long, and shall have a ramming face 25 mm square.
7.5 Procedure. curing, age at test, number of specimens shall be the same
as in 2 and 5.

8. TEST FOR FLEXURAL STRENGTH OF

MOULDED FLEXURE TEST SPECIMENS
8.1 This clause deals with the procedure for determining the flexural
strength of moulded concrete flexure test specimens.

8.2 Apparatus
8.2.1 The testing machine may be of any reliable type of sufficient
capacity for the tests and capable of applying the load at the rate specified
in 8.3. The permissible errors shall be not greater than & O-5 percent
of the applied load where a high degree of accuracy is required and not
greater than f 1.5 percent of the applied load for commercial type of use.
The bed of the testing machine shall be provided with two steel rollers,

16
 IS: 516 - 1959

38 mm in diameter, on which the specimen is to be supported, and these

rollers shall be so mounted that the distance from centre to centre is 60 cm
for 150 cm specimens or 40 cm for 10.O.cm specimens. The load shall bc
applied through two similar rollers mounted at the third points of the
supporting span, that is, spaced a+ 20or 13.3 cm cmtre to centre. The load
shall be divided equally between the two loading rollers, and all rollers
shall be mounted in such a manner that the load is applied axially and
without subjecting the specimen to any torsional stresses or restraints.
One suitable arrangement which complies .with these requirements is
indicated in Fig. 3.
8.3 Procedure -Test specimens stored in water at a temperature of
24 to 30C for 48 hours before testing, shall be tested immediately on
removal from the water whilst they are still in a wet condition. The di-
mensions of each specimen shall be noted before testing. X0 preparation
of the surfaces is required.
8.3.1 Placing the Specimen in ?he Testing Machine - The bearing sur-
faces of the supporting and loading rollers shall be wiped clean, and any
loose sand or other material removed from the surfaces of the specimen
where thev are to make cbntact with the rollers. The specimen shall then
be placed-in the machine in such a manner that the load shall be applied to
the uppermost surface as cast in the mould, along two lines spaced 20,O or
13.3 cm apart. The axis of the specimen shall be carefully aligned with
the axis of the loading device. NO packing shall be uscbd between the
bearing surfaces of the specimen and the rollers. The load shall be applied
without shock and increasing continuously at a rate such that the extreme
fihre stress increases at approximately 7 kg/sq cn./rnin, that is, at a
rate of loading of 400 kg/min for the 15.0 cm specimens and at a rate of
180 kq/min for the 10.0 cm specimens. The load shall be increased until
the specimen fails, and the maximum load applied to the specimen during
the test shall be recorded. The appearance of the fractured faces St con-
crete and any unusual features in the type of failure shall be noted..
8.4 Calculation - The flexural strength of the specimen shall be ex-
pressed as the modulus of rupture fb, which, if a equals the distance.
between the line of fracture and the nearer support, measured on the
centre line of the tensile side of the specimen, in cm, sh& be calculated
to the nearest 0.5 kg/sq cm as follows:
f,,= yr
b .,dr
when a is greater than 20.0 cm for 15.0 cm specimen, or greater than
13.3 cm for a 10.0 cm specimen, or
fbb= ?!a:
\
when a is less than 20.0 cm but greater than 17.0 cm for 15.0 cm speci-
men, or less than 13-3 cm but greater than 11-O cm for a 10.0 cm specimen

17
IS : 516 - 1959

where
b = measured width in cm of the specimen,
d = measured depth in cm of the specimen at the point of
failure,
I = length in cm of the span on which the specimen was sup-
ported, and
p = maximum load in kg applied to the specimen.
If u is less than 17.0 cm for a 15.0 cm specimen, or less than 11.0 cm
for a 10.0 cm specimen, the results of the test shall be discarded.

8.5 Report - The following information shall be included in the report

on each specimen:
4 identification mark,
b) date of test,
4 age of specimen,
4 curing conditions,
4 size of specimen,
f1 span length,
\ maximum load,
r$ position of fracture ( value a ),
9 modulus of rupture ( kg per sq cm ), and
4 appearance of concrete and type of fracture if these are unusual.
9. DETERMINATION OF THE MODULUS OF
ELASTICITY BY MEANS OF AN EXTENSOMETER
9.1 This clause specifies the procedure for making and curing test speci-
mens, determining the modulus of elasticity of concrete in compression
by means of an extensometer where the maximum nominal size of aggre-
gate does not exceed 38 mm.
9.2 Size of Specimens -The test specimens shall consist of- concrete
cylinders 15.0 cm in diameter and 30.0 cm long. Alternately, other sizes
of cylinders or square prisms may be used provided that the height/dia-
meter or height/width ratio is at least 2.
9.3 Sampling, apparatus and procedure shall be as described in 2.
9.4 Preparation of Test Specimens - The test specimens shall be pre-
pared in accordance with 2 and shall be stored in water at a temperature of
24 to 30C for at least 48 hours before testing. At least three specimens
shall be made and tested.
9.5 Age at Test-Normally test shall be made when the specimens
reach the age of 28 days.

18
SECTION CC
4___~~aro.. SECTION BB

t;
FIG. 3 hmt&mawr?rr FOR LOAD~G OF FLEXUPE TEST SPIXIMEN
6
E
,
5
9
 IS: 516 - 1959

9.6 In order to determine the compressive strength of the concrete, three

test specimens for compressive strength shall be made together with each
set of cylinders or prisms in accordance with 9.2. The test specimens for
compressive strength shall be made from the same sample of concrete as
the cylinders or prisms and shall be cured and stored under identical
conditions.

9.7 Apparatus

9.7.1 Testing Muchitte -The testing machine shall comply in all

respects with the requirements of 5.2.1 and in addition shall be capable
of maintaining the load at any desired value.
9.7.2 Exlertsometws -Two extensometers are required each having a
gauge length of not less than 10-2 cm and not more than half the length
of the specimen. They shall be capable of measuring strains to an accu-
racy of 2 x 1Od. Mirror extensometers of the roller or rocker type are
suitable.

9.8 Procedure - The three test specimens for compressive strength shall
first be tested in accordance with 5 and the average compressive strength
shall be recorded. Immediately on removing the cylinder or prism
from the water and while it is still in a wet condifion, the exte-
nsometcrs shall be attached at the ends, or on opposite; sides of
the specimen and parallel to its axis, in such a way that the gauge pints
are symmetrical about the centre of the specimen and in r10 case are nearer
to either end of the specimen than a distance equal to half the diameter
or half .the width of the specimen. The extensometers shall be fixed with
the recording points at the same end. The specimen shall be immediately
placed in the testing machine and accurately centred. The load shall be
applied continuously and without shock at a rate of 140 kg/sq cm/min
until in average stress of (C+S) kg:!sq cm is reached, where C is one-
third of the average compressive strength of the cubes calculated to the
neareat 5 kg/sq cm. The load shall be maintained at this stress for at
Ieast one minute and shall then be reduced gradually to an avenge stress
oi l-5 k&q cm when cxtensometer readings shall be taken. The load
~&3 be applied a second time at the sarn~~ rate until an average stress of
[C-+-M) kg/q cm ia reached. The load slliill be maintained at this figure
wi& extensometer reaamgs are taken. The load shall again be r&iced
graduatiy sml readings again taken at 1.5 kgsq cm. The load shall then
be app&d a third time and estensometer readings taken at ten approsi-
mately equal increments of stress up to an average stress of (C-!-l-S) kg/
sq cm. Readings shall be taken at each stage of loading with as littlc
delay as pssibk. If the overall strains observed on the second und third
readings differ by more than 5 percent, thr loading cycle sliall be repeattd
until the difference in strain between consecutive readings at (C+1.5) kg/
sq cm does not esceea 5 percent.

20
 IS : 516 - 1959

9.9 Calculation -The strains at the various loads in the last two cycles
shall be calculated separately for each extensometer and the results shall
be plotted graphically against the stress. Straight lines shall be drawn
through the points for each extensometer; the slopes of these two lines
shall be determined and from them the average value shall be found. If
the difference between the individual values is less than 15 percent of the
average value, this average value, expressed in kg/sq cm to the nearest
1.900 kg/sq cm shall be recorded as the modulus of elasticity of the con-
crete. If the di%rence is greater than 15 percent, the specimen shall be
re-centred in the testing machine and the test repeated. If the diierence
after re-centring and testing is still greater than 15 percent of the average
value, the results of the test shall be discarded.
9.30 Report -The following information shall be included in the report:
identification mark;
date of test;
age of specimen;
shape and nominal &men&ns of specimen;
modulus of elasticity; and
remarks, such as number of loading cycles.

1L DETERMINATION OF THE MHODULXJSOF

ELASTICITY BY ELECTRODYIUAMW MBTIWD

10.1 This clause specifies the procedure for determining the module of
elasticity of concrete by an electrodynamic method, namely by measuring
the natural frequency of the fundamental mode of longitudinal vibration
of concrete prisms. This is a non-destructive test and therefore the same
specimens may subsequently be used for the fIexural strength test specified
-in 8.
10.2 Specimens-The specimens shall in all respects comply with the
requirements of 9.2.
10.3 Apparatus - The apparatus shall consist of the following.
10.3.1 A variable frequency oscillator with a working range up to
10 000 cycles per second, reading to an accuracy of A@5 percent. A means
of varying the output power shall be incorporated, and the output power
shall be not less than 2 watts.
10.3.2 An electro-magnetic exciter unit of the moving-coil or variable
air-gap type. If the moving-coil type is used, the former and coil should
have as low an inertia as possible, the mass being not more than O-2 percent
of the mass of the specimen ( the former should be of light card or paper 1.
A suitable type of instrument is shown in Fig. 4. If a variable air-gap
exciter unit is used, this shall be of a similar type to the pick-up unit.

21
 LIGHT PAPCR fORMER THE FGRMER
Ah0 COIL MUST SLIDE LOOSELY IN
1% ANNULAR SPACE BETWEEN THE
POLES OF THE MAGNET -- -----,
, rEICITER

/-CLAMP OR SUPPOP PE R)*ANENT

lICI-UP UNIT-

NOT TO EXCEED &h L COIL OF 50

Of SPECIMEN

OETAIL Of EXCITER

*The a@hesive or other method of attachment should preferably allow paper cylinder to k detached after
test for further use.

Fit.. 4 .4urm~cExXx~ OF SPECIMEN FOITHL DETEZFMINATIOX OF MODULUS OF

ELASTICITY BY ,-AECTRODYNAMIC hiRT,WD
 IS: 516 - 19S9

10.3.3 An electro-magnetic pick-up unit oi the ordinary telephone type.

Alternatively, a piezo-electric gauge may be used, provided that its mass
isnot more tllan 0.2 percent cf the mass of the specimen.
10.3.4 A:I audio-frequency amplifier.
10.3.5 An amplitude indicator consisting of a voltmeter, milliammtter
or cathodc .ray oscilioscope.
10.3.6 A fixed clamp or support with a maximum width of ,,,th of the
length cf the specimen. If a variable air-gap exciter unit is used in con-
lunction with a variable air-gap pick-up, the support shall be metallic
arid earthed.
10.4 Procedure - Immediately on removal from water, except when
the specimen is less than 24 hours.old, and while still in a wet condition,
the specimen shall be clamped or balanced at its centro on the fixed sup-
port. Where a moving-coil type of exciter unit is used, the moving-coil por-
tion shall be fixed to the middle of one end face of the specimen as indicated
in Fig. 4. It may be fixed to the specimen by means of resin or other
suitable adhesive. The re<in can conveniently be applied with an electric
soldering iron. A disk of tinfoil, of 5 cm diameter, shall be lightly greased
to ensure adhesion and placed on the centre of the other end of the speci-
men, and the pick-up unit shall be placed with tht diaphragm as close
as possible to the foil but the pick-up unit shall not be allowed to touch
the tinfoil or the specimen. If a variable air-gai) exciter is used, this shall
be mounted in a.. similar manner to the pick-up, using a disk of tinfoil.
The exciter unit shall be driven by the variable frequency oscillator. and
the oscillations received by the pick-up unit shall be amplified hy the
audio-frequency amplifier and applied to the indicator in such a manner
as to show the amplitude of the oscillations received. The frequency of
excitation shall be varied until resonance is obtained in the fundamentril
mode of longitudinal vibration. The frequency shall be recorded as the
natural frequency of the fundamental mode of longitudinal vibration.
NOTE --. Resonancr is indiuted by a maximum deflection of the indicator. hut
,everal maxima mav IW ubtamed. and experience is necessary to know which is the
maximum required Freclurucics within + 10 pcrccnt of the expected value,
which may be calclllatrd Irom the formula glvcn in 10.6 should hc investi-
@cd Values nf the modulus of clasticitv range from 1.4 x 10 kg/sq cm for law-
quality concretes at tarly ages to 5 x 10 kg/sq cm for high-quality concretes ;ct
grratcr ages. This rel~resents a frvqurn<v range of lXfWJ/I Fycles per second b)
225ooo11 cycles per second. where 1 IS the Irngth of the specimen m cm. It is u~nlly
posstble to obtain resonance alsc, at 11~ Irequlv)ry of the first harmoure which
IS twice the fundamental freclcrncv and there two conditions arc normally the
moyt wrll defined.

10.5 Measurcmento -- The following measurements shall be made on

the specimen :
i a) Weight - The wet specimen shall be weighed to an accuracy of
0.25 percent.

23
IS: 516 - 19S9

b) Len@ -The length of the specimen shall be determined to an

accuracy of f 1 mm, the average being taken of at least four sym-
metrically placed measurements.
c) Depth an+ Breadth -The average depth and breadth of the speci-
meu shall be determined to an accuracy of + O-2 mm, the average
being taken in each case of at least six measurements spat d
eqqally along the length of the specimen.
10.6 Calculation - The density of the wet concrete shall be calculated
from the formula:
106x w
w=ixd
10.6.1 The dynamic modulus of elasticity shall then be calculated to
the nearest 1 000 kglsq cm from the formula:
E-=4383x lo-r*Z%c~
where
E = dynamic modulus of elasticity in kg per sq cm,
n = natural frequency of the fundamental mode of longitudinal
vibration of the specimen, in cycles per second,
w - density in kg per cu m,
W = weight in kg of the specimen,
L = length in cm of the specimen,
b = breadth in cm of the specimen, and
d = depth in cm of the specimen.
10.7 Number of Specimens -At least three specimens shall be tested
for each age of test.
10.8 Report - The following information shall be included in the report
on each specimen:
4 identification mark,
W date of test,
4 age of specimen,
d) curing conditions,
4 average dimensions of specimen,
f1 weight of wet specimen.
g) natural frequency of the fundamental mode of longitudinal vibration
of specimen, and
dynamic modulus of elasticity.

24
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 AMENDMENT NO. 2 JULY 1991
TO
IS 516 : 1959 METHODS OF TESTS FOR
STRENGTH OF CONCRETE
( puge6, clause 2.9.1 ) - Substitute the following for the existing
clause:
2.9.1 Cube Moulds - The mould shall be of 150 mm size conforming
to IS 10086 : 1982*.
( Page 6 ) - Insert the following foot-note at the bottom:
*specification for moulds for use in tests of cement and concrete.
( hge 7, &use 2.9.2 ) - Except the last sentence, substitute the
following for the existing matter:
The cylindrical moulds shall be of 150 mm diameter and 300 mm height
conforming to IS 10086 : 1982*.
( Page 7, clause 2.9.3 ) - Substitute the following for the existing
clause:
29.3 Tamping Bar - The tamping bar shall conform to 6.1(a) of
IS 10086 : 1982*.
( Page 7 ) - Insert the following foot-note at the bottom:
*Specification for moulds for use in tests of cement and concrete.
( pages 15 anal 16, c/muse 7.4.1 ) - Substitute the following for the
existing clause:
7.43 Beam Maulds - The beam moulds shall conform to IS 10086 :
1982.
In assembling the mould for use, the joints between the sections of the
mould shall be thinly coated with mould oil and a similar coating of
mould oil shall be applied between the contact surfaces of the bottom of
the mould and the base plate in order to ensure that no water escapes
during the filling. The interior faces of the assembled mould shall bc
thinIy coated with mould oil to prevent adhesion of the concrete.
( Page 15 ) - Insert the following foot-note at the bottom:
*Specification for moulds for use in tests of cement and concrete.

( Page 16, ciutise 7.4.2 ) -

Substitute the following for the existing
clause:
7.4.2 Tamping Qor - The tamping bar shall conform to 6.1(b) of
IS 10086 : 1982*.

(CED2)
Prlnted at Simco Printin Press. Delhi. India