Concrete Engineering

1. Concrete Superiority and
Resilience characteristics in
Construction

2. GENERAL IFORMATIONS OF
CONCRETE –
CEMENT, SAND, AGGREGATE,
ADMIXTURE & WATER

3. REFERENCES
• Indian Railway Unified Standard Specifications & schedule of
rates (USSOR) – (Works & Materials) – 2010 with CS no. 1 & 2
Total chapters – 26
• Chapter 3 - Plain Concrete ( cement, sand,
aggregate, admixtures)
• Chapter 26 - Mortars (water, cement, sand)

4. Specifications - Concrete
Ingredients of concrete
1. Cement
2. Fine Aggregate - Sand
3. Coarse Aggregate
4. Admixtures
5. Water

5. CEMENT
• The cement used shall be 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) 53 grade ordinary Portland cement conforming
to IS:12269
(d) Rapid hardening Portland cement conforming
to IS:8041

6. CEMENT
(e) Portland Slag cement conforming to IS:455
(f) Portland pozzolona cement (flyash 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.
(i) Low heat Portland cement conforming to IS:12600
(j) Sulphate resisting Portland cement conforming to
IS:12330.

7. CEMENT
• Different types of cement shall not be mixed together.
• 33 Grade cement - gain in strength continues beyond
28th day.
• Higher Grade cement
- heat of hydration is faster initially.
- Release of heat is highest in Grade 53 cement.
- hence be used only where there is the need for it
on design considerations.

8. Field Test on cement
1. The stitching of bag should be intact and original.
2. Check the grade of cement.
3. Check the date of manufacture---w-week, m-
month, y- year. it should be fresh & not older than
3 month. Older than 6 month is not to be used.
4. No lumps should be present.
5. Put hand in bag of cement and feel it , should feel
cool and rubbing between fingers should be silky.

9. Field Test on cement
6. When a handful cement dropped in water it should
float before sinking.
7. Immerse a small cube made of cement paste in
water and after 24 hours it should gain some
strength and its edges should be intact.
8. Weigh 5 bags of cement and the average weight
should be 50kg.
9. Cement bags should be properly stored.

10. CEMENT
Chloride Content
In terms of Correction Slip No.1 dated 26.04.2000 to
Concrete Bridge Code (Revised 1997), the total Chloride
content by weight in Cement shall not exceed the
following values.
(a)For Prestressed Concrete works
(i)Under extreme and very severe environment : 0.06%
(ii) Under severe, moderate and mild environment :
0.10%
(b) For R.C.C.Works : 0.15%

11. CEMENT
Compressive Strength
• Compressive strength requirement of ordinary
Portland cement of various grades when tested in
accordance with IS:4031 (part 6) shall be as under :
Sample Strength in N/mm2 - not less than for
Age at testing Gr.33 Gr.43 Gr.53
3 days. 16 23 27
7 days. 22 33 37
28 days. 33 43 53

12. CEMENT
Setting time
Setting time of cement of any type or any grade when
tested byVicat apparatus method described in IS:4031
shall conform to the following requirement.
(a) Initial setting time : Not less than 30 minutes
(b) Final setting time: Not more than 600 minutes

13. Fine Aggregate-Sand
• Aggregate passing through 4.75mm IS sieve is known
as fine aggregate.
• Fine aggregate shall consist of natural sand, crushed
stone sand or crushed gravel sand, stone dust or marble
dust, fly ash, Surkhi (crushed brick) or cinder
conforming to IS:2686.
• It shall be hard, durable, chemically inert, clean and free
from adherent coatings, organic matter etc.

14. Fine Aggregate-Sand
• Marine aggregate shall not be used for Reinforced
Concrete and Prestressed Concrete works.
(In terms of Correction Slip No.1 dated 26.04.2000 to Indian
Railways Concrete Bridge Code -Revised 1997)
• The maximum quantity of silt in sand shall not exceed
8%.
• The sum of the percentages of all deleterious material
shall not exceed 5%.

15. Indian standard soil classification system
Based on grain size

16. Fine Aggregate
Grading – On the basis of particle size, fine aggregate is
graded into four zones.
• The higher the Grading Zone, the finer the sand, with
Grading Zone I – coarsest and Grading Zone IV-Finest.
• It is recommended that fine aggregate conforming to
Grading Zone IV should not be used in reinforced concrete
unless tests have been made to ascertain the suitability of
proposed mix proportions.
• The grading shall be within the limits given inTable 26.1
below.

17. Fine Aggregate
IS Sieve
Percentage passing for
Grading Zone
I
Grading Zone
II
Grading Zone
III
Grading Zone
IV
10mm 100 100 100 100
4.75mm 90-100 90-100 90-100 95-100
2.36mm 60-95 75-100 85-100 95-100
1.18mm 30-70 55-90 75-100 90-100
600 microns 15-34 35-59 60-79 80-100
300 microns 5-20 8-30 12-40 15-50
150 microns 0-10 0-10 0-10 0-15

19. Fine Aggregate
i) Coarse sand
Its grading shall fall within the limits of grading Zone I, II, III of
Table 26.1.
Coarse sand shall have Fineness Modulus not less than 2.5.
ii) Fine sand
Its grading shall fall within the limits of Grading Zone IV of
Table 26.1.
Fine sand shall have Fineness Modulus not less than 1.0.
Use of sea sand shall not be allowed, unless otherwise
specified.

20. Fine Aggregate
• 26.1.3.8 Bulking –
• Fine aggregate, when dry or saturated, has almost the same
volume but dampness causes increase in volume.
• In case fine aggregate is damp at the time of proportioning
the ingredients for mortar or concrete, its quantity shall be
increased suitably to allow for bulkage, which shall be
determined by the method prescribed in Annexure 26.5. of
USSOR
• Table 26.4 gives the relation between moisture content and
percentage of bulking for guidance only.
• Bulkage % age may be assessed on prorata basis for the
different %age of moisture content present at the time of
using the fine aggregate or while making payments at the
time of measuring the same in case of supply of materials.

21. Fine Aggregate
Bulking of sand (Table 26.4)
Relation between moisture content and percentage of bulking for
guidance only.
Moisture contained
(% by weight)
Bulking % age (by volume)
1 8
2 15
3 20
4 25
5 30

22. Coarse Aggregate
• Aggregate, most of which is retained on 4.75mm IS
Sieve and contains only as much fine material as is
permitted in IS:383 for various sizes and grading is
known as Coarse aggregate.
• It shall consist of naturally occurring (uncrushed,
crushed or broken) stones or river bed shingle or pit
gravel.
• It shall be hard, strong, dense, durable and clean
and roughly cubical in shape.
• Marine aggregate shall not be used for reinforced
concrete and prestressed concrete bridges.

23. Coarse Aggregate
Size and Grading of Stone aggregate and gravel
• It shall be either graded or single sized as specified.
• Nominal size and grading shall be as under :
(a) Nominal sizes of graded stone aggregate or gravel shall
be 40, 20, 16, or 12.5 mm as specified.
(b) Nominal sizes of single sized stone aggregate or gravel shall
be 63, 40, 20, 16, 12.5 or 10 mm as specified.
For any of the nominal size, the proportion of other sizes as determined
by the method prescribed in Annexure 3.1 shall be in accordance with
Table.3.1 &Table.3.2.

24. GRADED STONE AGGREGATE OR GRAVEL
IS Sieve
Designation
Percentage passing (by weight) for nominal size
of
40 mm 20 mm 16 mm 12.5 mm
80 mm 100 -- -- --
40 mm 95 to 100 100 -- --
20 mm 30 to 70 95 to 100 100 100
16 mm -- -- 90 to 100 --
12.5 mm -- -- -- 90 to 100
10 mm 10 to 35 25 to 55 30 to 70 40 to 85
4.75 mm 0 to 5 0 to 10 0 to 10 0 to 10

25. SINGLE SIZED(UNGRADED) STONE AGGREGATE OR GRAVEL
IS sieve
Desig-
nation
Percentage passing (by weight) for nominal size
of
63 mm 40 mm 20 mm 16 mm 2.5 mm 10 mm
80 mm 100 -- -- -- -- --
63 mm 85-100 100 -- -- -- --
40 mm 0-30 85-100 100
20 mm 0-5 0-20 85-100 100
16 mm 85-100 100
12.5mm 85-100 100
10mm 0-5 0-5 0-20 0-30 0-45 85-100
4.75mm 0-5 0-5 0-10 0-20
2.36mm 0-5

27. Coarse Aggregate
• Size of Coarse aggregate
a) The nominal maximum size of coarse aggregate
should be as large as possible within limits specified
b) but in no case greater than one fourth of the
minimum thickness of the members, provided that the
concrete can be placed without difficulty to fill all
corners of the form and to surround all reinforcement.
For reinforced concrete work and prestressed concrete
work, aggregates having a nominal size of 20mm are
generally considered satisfactory.

28. Coarse Aggregate
In special cases larger size may be specifically permitted by the
Engineer but in no case the nominal maximum size in such
RCC/ PSC structures shall be more than 40mm.
b)For heavily reinforced concrete members, as in the case of
ribs of main beams, the nominal maximum size of aggregate
should usually be restricted to 5mm less than the minimum
clear distance between the main bars or 5mm less than the
minimum cover to reinforcement whichever is smaller.
-Where reinforcement is widely spaced as in solid slabs,
limitations on the size of the aggregate may not be so
important.

29. Coarse Aggregate
c) Coarse and fine aggregates shall preferably be
batched separately, specially for design mix concrete.
d)The largest possible size, properly graded, should be
used in order to reduce the water demand.
For high compressive strengths of concrete, this is
usually economical.

30. Coarse Aggregate
Testing of Coarse aggregate :
Coarse aggregate shall be tested for the following
(as per IS: 2386):
a) Determination of particle size and shape
The aggregate failing in the test should be got removed
from the site.
b) Estimation of organic impurities (As per IS: 2386 Part II):
c) Surface moisture
d) Determination of 10% fine value

31. Chemical Admixtures
General:- When required, admixtures of approved quality shall be
mixed with concrete, as specified.The admixtures shall conform
to IS : 9103.
Admixtures may be any one of the following classes for use in
concrete:-
(a)Water reducingAdmixtures
(b) Retarding Admixtures
(c) Accelerating Admixtures
(d)Water reducing and retarding Admixtures
(e)Water reducing and accelerating Admixtures
(f) Permeability reducing (water proofing)Admixtures

32. Chemical Admixtures
 Dosage of these admixtures may vary according to
manufacturer’s specification.
No admixtures shall be accepted for use in concrete
unless these are tested in accordance with IS: 9103 and
the test results are approved by the Engineer.
Manufacturer’s recommendation shall be carefully
followed so as to ensure complete solution of the
product or to prepare a standard solution of uniform
strength for easier use.

33. Special Precautions in use of Admixtures
Previous experience with and data on such materials
should be considered in relation to the likely standards of
supervision and workmanship to the work being specified.
Admixtures should not impair durability of concrete nor
combine with the cement to form harmful compounds nor
increase the risk of corrosion of reinforcement.
The workability, compressive strength and the slump loss
of concrete with and without the use of admixtures shall be
established during the trial mixes before use of admixtures.

34. Special Precautions in use of Admixtures
The relative density of liquid admixtures shall be
checked for each drum containing admixtures and
compared with the specified value before acceptance.
The chloride content of admixtures shall be
independently tested for each batch before acceptance.
If two or more admixtures are used simultaneously in
the same concrete mix, data should be obtained to
asses their interaction and to ensure their compatibility.

35. Chemical Admixtures
As stipulated in Paras 4.4.2 and 4.4.3 of Indian
Railways Concrete Bridge Code (Revised 1997), the
following should be strictly adhered to
i) Calcium chloride or admixtures containing calcium
chloride shall not be used in structural concrete
containing reinforcement, pre-stressing tendon or
other embedded metal.
ii)The admixture containing Cl & SO3 ions shall not be
used. Admixtures containing nitrates shall also not be
used. Admixtures based onThiocyanate may promote
corrosion and therefore shall be prohibited.

36. Water
• Water used for mixing and curing shall be clean and free
from injurious quantities of alkalies, acids, oils, salts,
sugar, organic materials, vegetable growth or other
substances that may be deleterious to bricks, stone,
concrete or steel.
• Potable water is generally considered satisfactory for
mixing.
• The pH value of water shall be not less than 6.

37. Water
• The following concentrations represent the maximum
permissible values: (of deleterious materials in water).
Reference may be made to Concrete Bridge Code (Revised 1997).
• (a) Limits of Acidity: To neutralize 200ml sample of
water, using phenolphthalein as an indicator, it should
not require more than 2 ml of 0.10 normal NaOH. The
details of test shall be as given in IS: 3025 (part 22).
• (b) Limits of Alkalinity: To neutralize 200ml sample of
water, using mixed indicator, it should not require more
than 10 ml of 0.10 normal HCl. The details of tests shall
be as given in IS: 3025 (part 23).

38. Water
• (c) Percentage of Solids: Maximum permissible limits of solids
when tested in accordance with IS: 3025 shall be as under:
Organic - 200 mg/litre
Inorganic - 3000 mg/litre
Sulphates (as SO4) - 500 mg/litre
Chlorides (as Cl) -
500 mg/ litre for PrestressedConcreteWork,
1000 mg/ litre for ReinforcedConcrete work and
2000 mg/ litre for Plain ConcreteWork.
Suspended matter - 2000 mg/litre

39. Water
• The physical and chemical properties of water used for
mixing and curing should conform to the requirements
of IS:456-2000.
• The contractor has to arrange good quality water for
construction indicating the source.
• Sea water shall not be used for mixing or curing.
• Frequency ofTesting for Quality -Water from each
source shall be tested before commencement of the
work and thereafter once in every three months till
completion of the work or when ordered.

40. DURABILITY OF CONCRETE
• Definition-
A durable concrete is one that performs satisfactorily in the
working environment during its anticipated exposure conditions
during service life.
The materials and mix proportions specified and used should be
such as to maintain its integrity and, if applicable, to protect
embedded metal from corrosion.

41. DURABILITY OF CONCRETE
Concrete structure should continue to perform its intended functions i.e.
- Maintain its required strength and serviceability, during the
specified or traditionally expected service life.
- Concrete must be able to withstand the processes of
deterioration to which it is expected to be exposed.
- Durability does not mean an indefinite life.

42. DURABILITY & CUBE STERNGTH
• The cube strength only indicates the strength of the structure at
the time of construction.
• Whereas Durability is the long term guarantee of the same
strength and serviceability of the structure.
• Concrete may have strength initially but may not be durable.

43. DURABILITY OF CONCRETE
The main characteristics influencing the DURABILITY of concrete is its
PERMEABILITY to the ingress of water, oxygen, carbon dioxide, chloride,
sulphate and other potentially deleterious substances.
Voids increase the permeability of concrete.
Permeability causes rusting of steel and spalling
(disintegration) of concrete.
Impermeability is governed by the constituents and
workmanship used in making the concrete

44. DURABILITY OF CONCRETE
Factors influencing durability are
• The environment/exposure conditions
• Cover to embedded steel
• The type and quality of constituent materials
• The cement content andW/C ratio
• Workmanship to obtain full compaction & efficient curing
• Shape & size of the member

45. DURABILITY OF CONCRETE
• Voids reduce the strength of concrete.With every
one percent entrapped air, the strength is
reduced by about 5% to 6%.
• Five percent entrapped air mean 30% loss of
strength.
• Compacting also helps eliminate stone pockets
and thereby eliminate all types of voids that may
possibly be left in the concrete, which causes
reduction in strength as well as durability.

46. Permeability test
As per CBC cs no.1,
(i) Permeability test has been made mandatory for
- all major bridges in all exposure conditions
- all RCC/PSC bridges when exposure condition is
severe/very severe or extreme.
(ii) Under mild and moderate environment, permeability
test shall be mandatory for
- all major bridges and
- for other bridges permeability test is desirable to the
extent possible.

47. PROCEDURE FOR MEASURING PERMEABILITY OF
CONCRETE
Test Specimen
• Test specimen of 200 mm dia and 120 mm thick shall be used.
After 24 hours of casting of specimen, central circular area of
100mm diameter shall be roughened with a wire brush on the
side on which the water pressure is to be applied.The
unroughened part of the side of the test specimen which is
subjected to water pressure is to be sealed with two coats of
cement water paste (W/C = 0.4).
Procedure:
a) After 28 days curing, test specimen is fitted in to a test
apparatus where water pressure acts on the required face and
remaining faces can be observed

48. PROCEDURE FOR MEASURING PERMEABILITY OF
CONCRETE
b) At first, a pressure of 1 bar (1kg/cm2) is applied for 48 hours, then 3
bar for 24 hours and 7 bar for 24 hours.
c) After the test, the specimen is split in the middle by compression
applied on two round steel bars lying on opposite sides, above and
below.The side after test specimen exposed to the water pressure
should face downwards.
• The greatest water penetration depth, is taken as the average value
of the greatest penetration depths on three test specimen.
• The depth of penetration of water should not be more than 25mm
other wise it is considered to be failed in permeability test.

51. Coatings for concrete (Concrete Bridge Code)

52. Thanks