Concrete is made up of ingredients like Cement, Fine Aggregate (Sand), Coarse Aggregate, Water and admixtures. Concrete mix design is done to Optimize the requirements of Cement, Sand, Aggregate and Water in order to ensure that concrete parameters in both Plastic Stage (like workability) and in Hardened Stage (like Compressive Strength and durability) are achieved. The Concrete mix design is as per Indian Standards (IS 10262) and might vary from country to country. The nominal mix design ratios available for concrete less than M30 in strength are only thumb rules and are generally over designed. As the actual site conditions vary and the mix design should be adjusted as per the location and other factors.

1. CONCRETE MIX DESIGN AS PER THE
GUIDELINES OF IS 10262.
Vinod Kumar Singh
Co-founder, www.Happho.com
Online Marketplace for Construction Material & One Stop Solution for
House Construction & Interiors 1

2. INTRODUCTION TO CONCRETE MIX
DESIGN
2

3. CONCRETE
Basic Definition:
Concrete is a composite material that essentially consists of water, a binding medium
embedded with Fine Aggregate (typically sand) and Coarse Aggregate (typically gravel) with
or without chemical and mineral admixture and filler.
Constituents:
•mixture of aggregate and paste
→paste 30 to 40%
portland cement 7% to 15% by Vol.
water 14% to 21% by Vol.
→Aggregates 60% to 70%
coarse aggregates
Fine aggregates
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4. Typical Concrete Proportion by Volume:
CONCRETE
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5. CONCRETE MIX DESIGN
The selection of concrete proportion involves a balance between economy and requirement of
workability, consistency, density, strength, and durability, for the particular application.
• Workability: The property of the concrete that determines its capacity to be placed and
consolidated properly and be finished without harmful segregation.
• Consistency: It is the relative mobility of the concrete mixture, and measured in terms of the
slump; the greater the slump value the more mobile the mixture.
• Strength: The capacity of the concrete to resist compression at the age of 28 days.
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6. CONCRETE MIX DESIGN
• Water-cement (w/c) : Defined as the ratio of weight of water to the weight of cement. This
ratio is used in mix design and considerably controls concrete strength.
• Durability: Concrete must be able to endure severe weather conditions such as freezing
and thawing, wetting and drying, heating and cooling, chemicals, deicing agents, and the
like. An increase of concrete durability will enhance concrete resistance to severe weather
conditions.
• Density: For certain applications concrete may be used primarily for its weight
characteristics. Examples are counterweights, weights for sinking pipelines under water,
shielding from radiation, and insulation from sound.
• Generation of heat: If the temperature rise of the concrete mass is not held to a minimum
and the heat is allowed to dissipate at a reasonable rate, or if the concrete is subjected to
severe differential or thermal gradient, cracking is likely to occur."
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7. CONCRETE MIX DESIGN
BACKGROUND DATA:
The following information for available materials will be useful in designing a CMD
for the intended application:
• Sieve analyses of fine and coarse aggregates.
• Specific gravities and absorption of aggregates.
• Mixing-water requirements of concrete developed from experience with available
aggregates.
• Relationship between strength and water-cement ratio.
• Specific gravity of Portland cement and other cementitious materials, if used.
• Optimum combination of coarse aggregates to meet the maximum density grading for mass
concrete.
Other data which can be useful are silt content (Fine Aggregate), Flakiness and
Elongation Index (Coarse Aggregate) 7

8. BASIC COMPONENTS IN CONCRETE
CEMENT Coarse Aggregate NATURAL SAND
WATER 8

9. BASIC FUNCTION OF PORTLAND CEMENT
• Dry powder of very fine particles
• Forms a paste when mixed with water
• Chemical reaction-Hydration
• Glues other materials
• Paste coats all the aggregates together
• Hardens and forms a solid mass
9

10. • Needed for two purposes:
• chemical reaction with cement
• Workability
• Only 1/3 of the water is needed for chemical reaction
• Extra water remains in pores and holes
• Results in porosity
• Good for preventing plastic shrinkage cracking and workability
• Bad for permeability, strength, durability.
BASIC FUNCTION OF WATER
10

11. FUNCTIONS AND IMPORTANCE OF
AGGREGATE IN CONCRETE APPLICATIONS.
11

12. CONCRETE MIX DESIGN AS PER IS
10262 GUIDELINES
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13. AGGREGATE
• Aggregate is relatively inexpensive and does not enter into complex chemical reactions
with water; it has been customary, therefore, to treat it as an inert filler in concrete.
• However, due to increasing awareness of the role played by aggregates in determining
many important properties of concrete, the traditional view of the aggregate as an inert filler
is being seriously questioned.
• It is true that aggregate strength is usually not a factor in normal concrete strength
because, with the exception of lightweight aggregates, the aggregate particle is several
times stronger than the matrix and the interfacial transition zone in concrete. In other
words, with most natural aggregates the strength of the aggregate is hardly utilized
because the failure is determined by the other two phases.
• There are, however, aggregate characteristics other than strength, such as the size,
shape, surface texture, grading (particle size distribution), and mineralogy which are known
to affect concrete strength in varying degrees.
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14. BASIC FUNCTIONS OF AGGREGATE
• Cheap fillers
• Hard material
• Provide for volume stability
• Reduce volume changes
• Provide abrasion resistance
14

15. NOMENCLATURE & CLASSIFICATION
Aggregates are generally classified according to particle size, bulk density, or source sieve).
• Coarse aggregate is used to describe particles larger than 4.75 mm, and the term fine
aggregate is used for particles smaller than 4.75mm; typically, fine aggregates contain
particles in the size range 75 µm to 4.75 mm, and coarse aggregates from 4.75 to about 50
mm, except for mass concrete which may contain particles up to 150 mm.
• Most natural mineral aggregates, such as sand and gravel, have a bulk density of 1520 to 1680
kg/m3
and produce normal-weight concrete with approximately 2400 kg/m3
unit weight.
For special needs, aggregates with lighter or heavier density can be used to make
correspondingly lightweight and heavyweight concretes. Generally, the aggregates with bulk
densities less than 1120kg/m3
are called lightweight and those weighing more than 2080
kg/m3
are called heavyweight
For the most part, concrete aggregates are comprised of sand, gravel, and crushed rock derived
from natural sources and, therefore, are referred to as natural mineral aggregates ( are
further classified as granite, limestone, basalt etc. depending upon their parent rock source)
On the other hand, thermally processed materials such as expanded clay and shale, which are
used for making lightweight concrete, are called synthetic aggregates. Aggregates made from
industrial by products, for instance, blast-furnace slag and fly ash, also belong to this category.15

16. AGGREGATE CHARACTERISTICS AND THEIR
SIGNIFICANCE
Generally, aggregate properties affect not only the concrete mixture proportions but also the behavior
of fresh and hardened concrete. Due to considerable overlap between the two, it is more appropriate
to divide the study of aggregate properties into three categories that are based on microstructural and
processing factors.
•Characteristics dependent on porosity: density, moisture absorption, strength, hardness, elastic
modulus, and soundness
• Characteristics dependent on prior exposure and processing factors: particle size, shape, and texture
• Characteristics dependent on chemical and mineralogical composition: strength, hardness, elastic
modulus, and deleterious substances present
•A knowledge of certain aggregate characteristics (i.e., density, grading, and moisture state) is required
for proportioning concrete mixtures. Porosity or density, grading, shape, and surface texture determine
the properties of plastic concrete mixtures.
•The mineralogical composition of aggregate affects its crushing strength, hardness, elastic modulus,
and soundness which, in turn, influence various properties of hardened concrete containing the
aggregate.
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17. AGGREGATE PROPERTIES
• Absorption capacity is defined as the total amount of moisture required to bring an
aggregate from the oven-dry to the SSD condition.
• SSD condition :When all the permeable pores are full and there is no water film on the
surface, the aggregate is said to be in the saturated-surface dry condition (SSD).
• Surface Moisture: The amount of water in excess of the water required for the SSD
condition is referred to as the surface moisture.
• Specific Gravity :defined as the density of the material including the internal pores.
• Bulk Density :defined as the mass of the aggregate fragments that would fill a unit volume.
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18. AGGREGATE PROPERTIES
Soundness:
An aggregate is considered unsound when the volume changes in aggregate induced by
weather (e.g., alternate cycles of wetting and drying, or freezing and thawing) ,result in the
deterioration of concrete.
IS limit:
• Fine Aggregate = 10% (weight loss of five cycles with Na2SO4)
• Fine Aggregate = 15% (weight loss of five cycles with MgSO4)
• Coarse Aggregate = 12% (weight loss of five cycles with Na2SO4)
• Coarse Aggregate = 18% (weight loss of five cycles with MgSO4)
Shape:
• Flakiness Index :Thickness being 0.6 times their mean dimension, contributes more surface
area for a unit volume occupied.
• Elongation Index :Greatest dimension being 1.8 times their mean dimension, contributes
more surface area for a unit volume occupied.
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19. AGGREGATE PROPERTIES
Shape:
• Flakiness Index :Thickness being 0.6 times their mean dimension, contributes more surface
area for a unit volume occupied.
Flakiness Index Apparatus Flaky Aggregate
19

20. AGGREGATE PROPERTIES
Shape:
• Elongation Index :Greatest dimension being 1.8 times their mean dimension, contributes
more surface area for a unit volume occupied.
Elongation Index Apparatus Elongated Aggregate
20

21. AGGREGATE PROPERTIES
Ideal Aggregate:
Neither Elongated Nor Flaky
21

22. AGGREGATE PROPERTIES
• Mechanical Properties:
Crushing strength, impact value abrasion resistance, and elastic modulus of aggregate are
interrelated properties, that are greatly influenced by porosity. Aggregates from natural sources
that are commonly used for making normal-weight concrete, are generally dense and strong;
therefore they are seldom a limiting factor to strength and elastic properties of concrete.
Indian Standard (IS) limit:
• Crushing and Impact Value :
Wearing surface = 30% & Non-wearing surface = 45%.
• Abrasion Resistance :
Wearing surface = 30% & Non-wearing surface = 50%.
• Fineness Modulus: Empirical factor called the fineness modulus is often used as an index of the fineness of
aggregate.
The fineness modulus is computed from screen analysis data by adding the cumulative percentages of
aggregate retained on each of a specified series of sieves, and dividing the sum by 100. The sieves used for
determining the fineness modulus are: No. 100 (150 µm), No. 50 (300 µm), No. 30 (600 µm), No. 16 (1.18
mm), No. 8 (2.36 mm), No. 4 (4.75 mm), 10 mm,20mm,40mm etc.
• Slit Content :Material finer than 75-µm (No. 200) sieve are generally called slit. They affect the workability
as water demand increases, strength is also influenced along with bonding. IS limit is 3% by weight.
22

23. AGGREGATE PROPERTIES
Size and Grading :
• Grading is the distribution of particles of a granular material among various size ranges, usually
expressed in terms of cumulative percentage larger or smaller than each of a series of sizes of sieve
openings, or the percentage between certain range of sieve openings.
• Size: The maximum size of aggregate is conventionally designated by the sieve size on which 15 percent
or more particles are retained. In general, the larger the maximum aggregate size, the smaller will be
the surface area per unit volume which has to be covered by the cement paste of a given water-cement
ratio.
Since the price of cement may be 10 to 15 times as much as the price of aggregate, any action that
saves cement without reducing the strength and workability of concrete can result insignificant
economic benefit
• There are several reasons for specifying grading limits and maximum aggregate size, the
most important being their influence on workability and cost.
For example, very coarse sands produce harsh and unworkable concrete mixtures, and very
fine sands increase the water requirement (therefore, the cement requirement for a given
water-cement ratio) and are uneconomical.
• Aggregates that do not have a large deficiency or excess of any particular size produce the
most workable and economical concrete mixtures.
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24. AGGREGATE PROPERTIES
IS Sieve
Size (mm)
Weight
Retained (gms)
Cum.Weight
Retained (gms)
%
Retained
%
Passing
10 0 0 0 100
4.75 120 120 4 96
2.36 450 570 19 81
1.18 390 960 32 68
0.600 870 1830 61 39
0.300 750 2580 86 14
0.150 360 2940 98 2
Pan 60 3000 - -
Fineness Modulus = Col.04/100 = 300/100 = 3
As per our experience Fine Aggregate with F.M of 2.7 to 3.0 are best suited concrete
application
Fineness Modulus (F.M) solved example :
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25. IMPORTANCE OF AGGREGATE
• Aggregate primarily acts as a inert filler, but has secondary influences on various concrete
properties.
• Awareness about the role played by aggregate in concrete can be instrumental in exploiting the
use of the same in achieving concrete properties as per intended requirements, which would be
of high performance and economical.
• It is inappropriate to treat the aggregate with any less respect than cement.
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26. DESIGN STIPULATIONS
• Characteristic Compressive Strength
(basic mix design criteria, required to ascertain Target mean strength)
• Maximum size of Aggregate
(Governs water and cement content)
• Degree of workability
( basic placement requirement, governs water content)
• Degree of quality control
(Assumption of standard deviation, depending upon site quality control)
• Type of Exposure
(To fix minimum cement content ,maximum water - cement ratio and minimum grade of
concrete)
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27. TEST DATA FOR MATERIALS
INGREDIENTS TO BE PHYSICALLY CHARACTERIZED
• CEMENT
ꟷ Type & Grade ( w/c ratio for target mean strength)
ꟷ Specific Gravity (calculation of various ingredients)
• AGGREGATE
ꟷ Specific gravity (calculation of various ingredients)
ꟷ Water absorption (Site adjustments)
ꟷ Free surface moisture (Site adjustments)
ꟷ Sieve Analysis (proportioning of fine & coarse aggregate)
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28. STEP-01 :TARGET MEAN STRENGTH
• In order that not more than the specified proportion of test results are likely to fall below the
characteristic strength.
f t.m.s = f ck + t X s
f t.m.s = target mean strength at 28 days.
f ck = characteristic compressive strength at 28 days.
t = a statistic, depending upon the accepted proportion of low results = 1.65
s = standard deviation (as per table 01)
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29. STEP-01 :TARGET MEAN STRENGTH
• Assumed standard deviation as per IS 456:2000
Table – 01
29

30. STEP-02 : SELECTION OF WATER CEMENT RATIO
• Different cements and aggregates of different maximum size ,grading surface texture, shape
and other characteristic may produce concretes of different compressive strength for the same
water cement ratio
•The relationship between strength and water cement ratio should be preferably established for
the materials actually to be used.
•In the absence of such data, the preliminary water- cement ratio corresponding to the target
strength at 28 days may be selected from the relation shown in fig 01,alternatively by fig 02.
30

31. STEP-02 : SELECTION OF WATER CEMENT RATIO
Fig 01 Fig 02
31

32. STEP – 03 ESTIMATION OF AIR CONTENT
•Approximate amount of entrapped air to be expected in normal ( non-air entrained) concrete
given in Table 02.
Table 02
32

33. STEP -04 : ESTIMATION OF WATER CONTENT AND
FINE TO TOTAL AGGREGATE RATIO
•Approximate sand and water content per cubic meter of concrete for grades upto M35
Table 03
33

34. STEP -04 : ESTIMATION OF WATER CONTENT
AND FINE TO TOTAL AGGREGATE RATIO
•Approximate sand and water content per cubic meter of concrete for grades above M 35.
Table 04
34

35. ADJUSTMENTS OF VALUES IN WATER CONTENT AND
SAND PERCENTAGE FOR OTHER CONDITIONS
Table 05
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36. STEP – 05: CALCULATION OF CEMENT CONTENT
•Water – cement ratio arrived at step-02
•Water content arrived at step – 04
Cement Content = Water content / water-cement ratio
Arrived cement content and water - cement needs to be checked with Table-06
Table – 06 (as per IS 456:2000)
36

37. ENVIRONMENTAL EXPOSURE CONDITIONS.
Table – 07 (defined as per IS 456:2000):
37

38. STEP -06 : CALCULATION OF AGGREGATE
CONTENT
•The total aggregate content per unit volume of concrete may be calculated from the following
equations
V = [ W + C/SC + 1/p * fa /Sfa] x 1/1000
&
V = [ W + C/SC + 1/1-p * ca /Sca] x 1/1000
Where
V = absolute volume of fresh concrete, which is equal to gross volume (m3
) minus the volume of
assumed entrapped air.
W = mass of water (kg) per m3
of concrete [arrived in step -04]
C = mass of cement (kg) per m3
of concrete [arrived in step -05]
p = ratio of fine aggregate to total aggregate by absolute volume [arrived in step -06]
fa, ca =total mass of fine aggregate and coarse aggregate (kg) per m3 of concrete respectively.
Sfa, Sca = specific gravities of saturated surface dry fine aggregate and coarse aggregate
respectively. [test data of materials]
38

39. STEP -07 COMBINATION OF DIFFERENT
AGGREGATE FRACTIONS
•Coarse aggregate of different sizes should be combined in suitable proportions as to result in
an overall grading confirming to IS 383 – 1970 for the particular nominal maximum size of
aggregate.
•Combined gradation criteria for 20mm graded maximum size of aggregate.
IS Sieve Sizes (mm) Combined % passing (as per IS:383)
20
10
4.75
2.36
95 -100
25-55
0-10
-
39

40. MIX PROPORTION
•Arrived initial trial mix proportion :
Water Cement Fine Aggregate Coarse Aggregate
Step -04 Step -05 Step -06 Step -06
For Example:
Water Cement Fine Aggregate Coarse Aggregate
191.6 416.5 597 1179
0.46 1 1.43 2.83
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41. GUIDELINES FOR SUBSEQUENT MIX TRIALS
• Subsequent trial mixes may be undertaken if the results are not meeting desired fresh and
hardened concrete properties.
Observation/Results Guidelines
1.Undersanded
2.Non Cohesive
3.Lacks workability
4.T.M.S not achieved
Increase sand content in multiples of 5%.
Vary proportions of aggregates amongst themselves
Increase water content (maintaining w/c ratio i.e
increasing cement content)
Reduce w/c ratio in multiples of 5% (maintaining total
water content i.e increasing cement content)
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42. GOOD CONCRETE = GOOD MIX DESIGN +
GOOD QUALITY CONTROL
42