PROPERTIES OF CONCRETE

A good concrete should have three basic qualities :

a) Strength

b) Workability

c) Durability

Table 1: Nominal Mixes As Per IS: 456-2000

(Fine Aggregate of Zone II As Per IS: 383- 1970)

Grade of

concrete

As per

IS:383-1970

Max size of

graded

coarse

aggregate

Mix ratio by wt Max

W/C

ratio

Max

cement

aggregate

ratio by

mass

Cement Fine

aggregat

e

Coarse

aggregat

e

M20

M20

M20

10

20

40

1 : 1.8 : 2.7

1 : 1.5 : 3.0

1 : 1.3 : 3.2

0.60

0.60

0.60

1:5

1:5

1:5

Proportions by weight can be converted to proportions by volume, by

dividing with the bulk density of the materials available for use at site. The bulk density of sand may be taken 1.44 Kg/lit

Table 2: Grades Of Concrete As Per IS:456-2000

Group Grade

Designation

Specified characteristic

compressive strength of

150mm cube at 28 days

N/mm²

Ordinary

Concrete

M10

M15

M20

10

15

20

Standard

Concrete

M25

M30

M35

M40

M45

M50

M55

25

30

35

40

45

50

55

High Strength

Concrete

M60

M65

M70

M75

M80

60

65

70

75

80

DURABILITY OF CONCRETE

• A durable concrete is one that performs satisfactorily in the working

environment under its anticipated exposure conditions during

service.

• Main characteristics influencing the durability of concrete is its

permeability to ingress of water, oxygen, carbon dioxide, chloride,

sulphate and other potentially deleterious materials.

• Factors influencing durability include

a) The environment

b) The cover to embedded steel

c) The type and quality of constituent materials

d) The cement content and water/cement ratio of the concrete

e) Workmanship, to obtain full compaction and efficient curing

f) The shape and size of the member

STATISTICAL PRINCIPLE

For assessing the acceptance criteria of concrete on statistical principles a large number of cube test results are needed.

At a given stage of construction, let the cube strength of‘n’ samples be available. The strength of each sample is theaverage strength of 3 samples. The sampling is also done in arandom manner.

If the strength of ith sample = fi

Mean strength, fm = Σ fi / n

Deviation of each sample from mean = (fm –fi )

Standard deviation = √Σ (fm –fi )2/(n-1)

The value of standard deviation will be low in case of goodcontrol and high in case of lax control. The acceptability ofconcrete depends upon achieving a desired mean strength andkeeping the deviation small.

Acceptance criteria as per old code

a) The grade of concrete is specified. M25 concrete means

concrete with a characteristic strength of 25 MPa at 28 days

curing.

b) A target mean strength is fixed.

ft = fck + k x s

( The value of k for calculating ft is taken as 1.65, which gives

a probability of not more than 5% of the samples tested will

fall below fck)

c) Each sample is checked for acceptability. Test strength of

each sample will be the average of three specimen with

individual variation being not more than ±15% of the average.

Clause 15.1 of IS: 456-1978

a) Accept all samples with fi ≥ fck

b) For samples with strength less than fck two checks are

applied. Both checks must be satisfied

• First check : fi should not be less than the larger of two

values.

(i) fck – 1.35 x s

(ii) 0.8 x fck

• Second check : Average strength of all the samples is

not less than fck + 1.65 [ 1-√(1/n)] s

Clause 15.2 of IS: 456-1978

a) Reject the concrete if fi is less than the greater of

(i) fck – 1.35 x s

(ii) 0.8 x fck

b) Reject the concrete also if fi < fck + [1.65 – (3/√n)] s

Note : concrete which does not meet the requirement of Clause

15.1 but has a strength greater than required by clause 15.2

can be accepted at the discretion of the designer.

The acceptance criteria as per new code is :

a) fm ≥ fck + 0.825 x s or (fck +4) MPa , whichever is greater

AND

b) fi ≥ (fck – 4) MPa

Where,

fm = Mean of four results in a group

fi = Strength of any individual sample

s = Established standard deviation rounded off to nearest

0.5 MPa

Note :- When sufficient number of samples have not accumulated, astandard deviation of 4.0 MPa is assumed for M20 & M25concrete. While 5.0 MPa is taken for M30 to M50. Thecalculated value of ‘s’ is used as soon as 30 results areavailable.

Acceptance criteria as per new code

( BASED ON IS:456 – 2000)

METHOD OF CONCRETE MIX DESIGN

Step 1 :- Work out the Target mean strength of concrete from the

relation:

Where, Target average compressive strength at 28 days

characteristic compressive strength at 28 days

s = Standard Deviation

t = 1.65 (as per IS:456-2000 clause 9.2.2 )

stffckck

x +=

=ckf

=ckf

Table 3: Assumed Standard Deviation For Three Strength Groups

Grade of Concrete Assumed standard

deviation

MPa

M10

M15 3.50

M20

M25 4.00

M30

M35

M40

M45

M50

5.00

The above values correspond to the site control having proper storage of

cement; Weigh batching of all materials; controlled addition of water; regular

checking of all materials, aggregate grading and moisture content; andperiodic checking of workability and strength. Where there is deviation from

the above, the values given in the above table shall be increased by 1 N/mm²

Step 2 :-

Find out the value of W/C ratio against the target mean strength

from the curves available for the purpose. Select the appropriate

curve for the type of coarse aggregate and the type of cement

being used.

Step 3 :-

For durability consideration check the obtained free water-

cement ratio from appropriate table of IS:456-2000. If required

use lower value of water cement ratio.

Step 4 :-

As per clause 7 page 17 of IS:456-2000 find out the degree of

workability required for the job.

Step 5 :-

From table 4, find out the quantity of free water in Kg/m³ for the

type and maximum size of aggregate being used and for the

required workability and normal- air entrained concrete.

Step 6 :-

Find out the cement content in Kg/m³ from the information of

step 2 and step 5.

For durability consideration, check the minimum cement

content , if required take higher value.

Step 7 :-

Find out the density of concrete in Kg/m³ for different maximum

sizes of coarse aggregate corresponding to particular value of

combined specific gravity of aggregates from the given tables

5,6 &7.

Step 8 :-

Find out the aggregates content per cum of concrete.

Total aggre = conc density – Free water – cement content(Kg/m³ ) (Kg/m³ ) (Kg/m³ ) (Kg/m³ )

ratio cement Water

content water Free content Cement =

Step 9 :-

Find out the proportions of sand (percent) of the total aggregate

from table 8 for particular maximum size of coarse aggregate,

required workability, zone of sand and water- cement ratio. Find

out the quantity of fine aggregates in Kg/m³ from total aggregate

calculated in step 8 above.

Step 10 :-

Find out the quantity of coarse aggregate in Kg/m³ by

subtracting the quantity of fine aggregate from total aggregates.

Step 11 :-

If the coarse aggregates are in more than one fraction , they

shall be combined in a suitable proportion to get a graded

coarse aggregate as per IS: 383-1970. In general, if the coarse

aggregates are in single size as per IS: 383-1970, they shall be

combined as follows for obtaining a combined graded

aggregate.

(a) 10 & 20 mm aggregate in ratio 1:2

(b) 10, 20 & 40 mm aggregate in ratio 1:1.5:3

IMPORTANT NOTE

THE CALCULATED MIX PROPORTIONSMUST BE CHECKED BY TRIAL MIXES FORREQUIRED SPECIFICATIONS, AND AS PERREQUIREMENTS SUITABLE ADJUSTMENT INTHE MIX PROPORTION SHOULD BE DONE.

COMPRESSIVE STR VS W/C RATIO(Uncrushed coarse aggregate)

F

E

D

C

B

A

80.0

70.0

60.0

50.0

40.0

30.0

20.0

10.0

0.00.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70

WATER – CEMENT RATIO

28

–D

AY

CO

MP

R S

TR

OF

CO

NC

RE

TE

(

N/m

m²)

A=21.6 – 25.0 N/mm² B=25.0 – 29.8 N/mm²

C=29.8 – 35.0 N/mm² D=35.0 – 41.5 N/mm²

E=41.5 – 48.0 N/mm² F=48.0 – 53.4 N/mm²

(Values given above correspond to the 7- day

strength of cement tested according to

IS: 4031-1968)

COMPRESSIVE STR VS W/C RATIO(Crushed coarse aggregate)

F

E

D

C

B

A

80.0

70.0

60.0

50.0

40.0

30.0

20.0

10.0

0.00.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70

WATER – CEMENT RATIO

28

–D

AY

CO

MP

R S

TR

OF

CO

NC

RE

TE

(

N/m

m²)

A=21.6 – 25.0 N/mm² B=25.0 – 29.8 N/mm²

C=29.8 – 35.0 N/mm² D=35.0 – 41.5 N/mm²

E=41.5 – 48.0 N/mm² F=48.0 – 53.4 N/mm²

(Values given above correspond to the 7- day

strength of cement tested according to

IS: 4031-1968)

Water cement ratio & cement contents for Durability

Type of

Exposure

Plain Cement Concrete Reinforced Cement Concrete

Min

cement

Kg/m³

Max

Free

W/C

Min

grade of

concrete

Min

cement

Kg/m³

Max Free

W/C

Min grade

of concrete

Mild 220 0.6 - 300 0.55 M20

Moderate 240 0.6 M15 300 0.5 M25

Severe 250 0.5 M20 320 0.45 M30

Very

Severe

260 0.45 M20 340 0.45 M35

Extremely Severe

280 0.40 M25 360 0.4 M40

Note :- Min cement content value applies to 20mm max size of agg

Adjustments to minimum cement content

for aggregates (other than 20mm max size of agg)

Sl No. Nominal max aggregate size Adjustments to minimum

cement content

1. 10 +40

2. 20 0

3. 40 -30

Note :-a) Cement content prescribed in the table is irrespective of the grades of

cement and is inclusive of mineral admixtures like fly ash, silica fume etc.

b) The additions such as fly ash or ground granulated blast furnace slag may

be taken into account in the concrete composition with respect to the

cement content and water cement ratio if the suitability is established and

as long as the maximum amounts taken into account do not exceed the

limit of pozzolona and slag specified in IS 1489(Part I) and IS 455

respectively.

Maximum size of aggregate (mm)

Type of aggregate

Slump (mm) - 25-75 50-100 100-180

Compacting factor

0.75-0.80 - - -

Degree of workability

Very low Low Medium High

10Uncrushed 150 205 220 240

Crushed 180 235 250 265

20Uncrushed 140 180 195 210

Crushed 170 210 225 245

40

Uncrushed 120 160 175 190

Crushed 155 190 205 220

Table 4:Approx Free water content(kg/m³)With non air- entrained concrete

(Normal entrapped air)

When coarse and fine aggregates of different types are used, the free water content is estimated by the expression : , where,

= Free water content appropriate to type of fine aggregate

= Free water content appropriate to type of coarse aggregate

cfWW3

1

3

2+

c

f

W

W

Table 5:Estimated wet density of fully compacted

concrete(kg/m³)(Max size of saturated & surface dry aggregate 10 mm for first trial)

Free water content

(Kg/m³)

Specific gravity for combined aggregates

2.4 2.5 2.6 2.7 2.8 2.9

130 2250 2320 2390 2460 2530 2600

140 2235 2305 2375 2445 2515 2585

150 2220 2290 2360 2430 2500 2570

160 2205 2275 2345 2415 2485 2555

170 2190 2260 2330 2400 2470 2540

180 2175 2245 2315 2385 2455 2525

190 2160 2230 2300 2370 2440 2510

200 2145 2215 2285 2355 2425 2495

210 2130 2200 2270 2340 2410 2480

220 2115 2185 2255 2325 2395 2465

230 2100 2170 2240 2310 2380 2450

240 2085 2155 2225 2295 2365 2435

250 2070 2140 2210 2280 2350 2420

The table is worked out for cement content 330 kg/m³. For each 20 Kg difference in cement content from 330 Kg correct the weight per m³, 3 Kg in the same direction.

Table 6:Estimated wet density of fully compacted concrete(kg/m³)

(Max size of saturated & surface dry aggregate 20 mm for first trial)

Free water content

(Kg/m³)

Specific gravity for combined aggregates

2.4 2.5 2.6 2.7 2.8 2.9

120 2285 2355 2425 2495 2565 2635

130 2270 2340 2410 2480 2550 2620

140 2255 2325 2395 2465 2535 2605

150 2240 2310 2380 2450 2520 2590

160 2225 2295 2365 2435 2505 2525

170 2210 2280 2350 2420 2490 2560

180 2195 2265 2335 2405 2475 2545

190 2180 2250 2320 2390 2460 2530

200 2165 2235 2305 2375 2445 2515

210 2150 2220 2290 2360 2430 2500

220 2135 2205 2275 2345 2415 2485

230 2120 2190 2260 2330 2400 2470

The table is worked out for cement content 330 kg/m³. For each 20 Kg difference in cement content from 330 Kg correct the weight per m³, 3 Kg in the same direction.

Table 7:Estimated wet density of fully compacted concrete(kg/m³)

(Max size of saturated & surface dry aggregate 40 mm for first trial)

Free water content

(Kg/m³)

Specific gravity for combined aggregates

2.4 2.5 2.6 2.7 2.8 2.9

100 2335 2405 2475 2545 2615 2685

110 2320 2390 2460 2530 2600 2670

120 2305 2325 2445 2515 2585 2655

130 2290 2360 2430 2500 2570 2640

140 2275 2315 2415 2485 2555 2625

150 2260 2330 2400 2470 2540 2610

160 2245 2315 2385 2455 2525 2595

170 2230 2300 2370 2440 2510 2580

180 2215 2285 2355 2425 2495 2565

190 2200 2270 2340 2410 2480 2550

200 2185 2255 2325 2395 2465 2535

210 2170 2240 2310 2380 2450 2520

The table is worked out for cement content 330 kg/m³. For each 20 Kg difference in cement content from 330 Kg correct the weight per m³, 3 Kg in the same direction.

Zone

of FA

W/C

ratio

10mm aggregate 20 mm aggregate 40 mm aggregate

VL L M H VL L M H VL L M H

I

0.3 43-53 46-56 49-60 54-67 32-39 35-42 39-47 44-53 27-33 29-35 33-39 38-46

0.4 46-56 48-58 51-62 57-69 34-42 37-45 41-49 46-56 29-35 31-38 35-42 41-49

0.5 48-58 50-61 53-65 59-72 37-45 39-47 43-52 48-59 31-38 33-41 37-44 43-52

0.6 50-61 52-63 56-68 62-75 39-47 41-50 45-54 50-61 33-41 36-43 39-47 45-54

0.7 52-64 55-66 58-70 64-77 41-50 44-53 47-57 53-64 36-44 38-46 42-50 47-57

II

0.3 36-43 37-46 40-49 44-54 27-32 28-35 32-39 35-44 22-27 23-29 27-33 31-38

0.4 37-46 39-48 42-51 46-57 28-34 30-37 33-41 37-46 24-29 25-31 28-35 32-41

0.5 39-48 41-50 44-53 47-59 30-37 32-39 35-43 39-48 25-31 27-33 30-37 34-43

0.6 41-50 42-52 45-56 49-62 32-39 34-41 36-45 41-50 27-33 29-36 32-39 36-45

0.7 42-52 44-55 47-58 51-64 34-41 36-44 38-47 43-53 29-36 31-38 34-42 38-47

III

0.3 29-36 32-37 33-40 37-44 23-27 24-28 27-32 30-35 18-22 20-23 22-27 26-31

0.4 31-37 33-39 35-42 38-46 24-28 26-30 28-33 31-37 20-24 21-25 24-28 27-32

0.5 32-39 34-41 36-44 40-47 25-30 27-32 29-35 33-39 21-25 23-27 25-30 29-34

0.6 34-41 36-42 38-45 42-49 27-32 29-34 31-36 35-41 23-27 24-29 27-32 30-36

0.7 35-42 37-44 39-47 43-51 28-34 30-36 32-38 36-43 24-29 26-31 29-34 32-38

IV

0.3 26-29 27-32 29-33 32-37 19-23 21-24 23-27 26-30 16-18 18-20 19-22 22-26

0.4 27-31 29-33 30-35 34-38 21-24 22-26 24-28 28-31 17-20 19-21 20-24 24-27

0.5 28-32 30-34 32-36 35-40 22-25 24-27 26-29 29-33 18-21 20-23 22-25 25-29

0.6 30-34 31-36 33-38 36-42 23-27 25-29 27-31 30-35 20-23 22-24 23-27 26-30

0.7 31-35 32-37 35-39 37-43 25-28 26-30 28-32 32-36 21-24 23-26 25-29 28-32

Table 8: Proportion of fine aggregate with different workability

IS Sieve

Designation

Percentage passing for Single Sized Aggregate of

Nominal Size

Percentage passing for Graded

Aggregate of Nominal Size

63mm 40mm 20mm 16mm 12.5mm 10mm 40mm 20mm 16mm 12.5mm

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

80mm 100 - - - - - 100 - - -

63mm 85-100 100 - - - - - - - -

40mm 0-30 85-100 100 - - - 95-100 100 - -

20mm 0-5 0-20 85-100 100 - - 30-70 100 - -

16mm - - - 85-100 100 - - - 90-100 -

12.5mm - - - - 85-100 100 - - - 90-100

10mm 0-5 0-5 0-20 0-30 0-15 85-100 10-35 25-55 30-70 40-85

4.75mm - - 0-5 0-5 0-10 0-20 0-5 0-10 0-10 0-10

2.36mm - - - - - 0-5 - - - -

Table 9: Grading requirements of Coarse aggregates (IS:383-1970)

Table 10 : Grading Requirements For Fine Aggregates (IS :383-1970)

� For crushed stone sands, the permissible limit on 150 micron IS sieve is increased by 20 %.

� Fine aggregate complying with the requirements of any of the grading zone in this table is

suitable for concrete.

� It is recommended not to use the fine aggregate conforming to the grading zone IV in

reinforced concrete unless tests prove it suitable for the purpose.

� Where concrete of high strength and good durability is required, fine aggregate conforming

to any of the four zones can be used, but the concrete mix should be properly designed. As

the fine aggregate grading becomes progressively finer, the ratio of fine aggregate to coarse

aggregate should be progressively reduced.

IS Sieve

Designation

Percentage Passing For Grading Zone

I II III IV

10 mm 100 100 100 100

4.75 mm 90-100 90-100 90-100 90-100

2.36 mm 60-95 75-100 85-100 95-100

1.18 mm 30-70 55-90 75-100 90-100

600 micron 15-34 35-59 60-79 80-100

300 micron 05-20 08-30 12-40 15-50

150 micron 00-10 00-10 00-10 00-15

Exposure Conditions

Sl

No.

Exposure

condition

Description

1. Mild �Concrete surfaces protected against

weather or aggressive conditions, except

those situated in coastal areas.

2. Moderate �Concrete surfaces sheltered from severe

rain or freezing whilst wet

�Concrete exposed to condensation and rain

�Concrete continuously under water

�Concrete in contact or buried under non

aggressive soil / ground water

�Concrete surfaces sheltered from saturated

salt air in coastal area

Sl

No.

Exposure

condition

Description

3. Severe �Concrete surfaces exposed to severe rain,

alternate wetting and drying or occasional

freezing whilst wet or severe condensation

�Concrete completely immersed in sea water

�Concrete exposed to coastal environment

4. Very

Severe

�Concrete surfaces exposed to sea water

spray, corrosive fumes or severe freezing

conditions whilst wet

�Concrete in contact with or buried under

aggressive sub- soil/ ground water

5. Extreme �Surface of members in tidal zone

�Members in direct contact with liquid/ solid

aggressive chemicals

Sl

No.

Placing conditions Degree of

workability

Slump

(mm)

1. �Blinding Concrete

�Shallow Sections

�Pavements using pavers

Very low 0.75-0.80

(CF)

2. �Mass Concrete

�Lightly reinforced sections in slabs,

beams, walls, columns

�Floors

�Hand placed pavements

�Canal linings

�Strip footings

Low 25-75

3. �Heavily reinforced sections in slabs,

beams, walls, columns

�Slipform work

�Pumped concrete

Medium 50-100

to

75- 100

4. �Trench fill

�In-situ piling

High 100- 150

5. �Tremie Concrete Very High By flow

determination

Workability of Concrete

Example 1:-

A mix is required to be designed for M20 grade of concrete which is

to used in lightly reinforced slab. Other details are as given below :

Standard deviation from

previous relevant work : 4.0 N/mm²

Required workability : (low) slump (25-75 mm)

Exposure : mild

Maximum free W/C ratio : 0.55

Minimum cement content : 300 Kg/ m³

Maximum size of aggregate : 20mm (uncrushed)

Type of sand : River sand

Cement : OPC 43 Grade

Other Details : The sand and aggregate has

been used in the

construction since the last

40 years and they are found

to be quite good.

Test results of materials :

Cement 7 days compressive strength : 39.5 N/mm²

Sand grading : Zone II

Aggregate grading : 20- 05 mm graded

Specific Gravity of Sand : 2.7

Specific Gravity of Aggregate : 2.7

Water absorption of sand : 1.4%

Water absorption of aggregate : 0.9%

Bulk density of room dry sand : 1.52 Kg/lit

Bulk density of room dry aggregate : 1.47 Kg/lit

Step 1 :-

Target mean strength of concrete,

= 20 + 1.65 x 4.0

= 26.6 N/mm²

Step 2 :- Selection of free w/c ratio

7- day compressive strength of cement = 39.5 N/mm²

Type of aggregate = Uncrushed (River gravel)

Therefore, from the appropriate curve, the w/c ratio for target

strength of 26.6 N/mm² is 0.51.

The value is selected as the same is less than specified max w/c

ratio of 0.55

s65.1f fckck

_

+=

Solution :-

Step 3 :- Selection of free water content

From table, for 20mm uncrushed aggregate and river sand, for required workability of 25-75 mm slump, free water content is found to be 180 kg/m³

Step 4 :- Determination of cement content

w/c ratio = 0.51

Water = 180 kg/m³

Cement = 180/0.51 = 353 kg/m³

The value of cement content is higher than the specified minimum cement content of 300 kg/m³, hence accepted

Step 5 :- Determination of concrete density

Specific gravity of combined aggregates = 2.7

Maximum size of aggregate = 20mm

Free water content = 180 kg/m³

Density of concrete ( from table ) = 2408 kg/m³

Step 6 :- Determination of aggregate quantity

Concrete density = 2408 kg/m³

Cement content = 353 kg/m³

Water content = 180 kg/m³

Total aggregates = (2408 – 353 – 180) kg/m³

= 1875 kg/m³

Step 7 :- Determination of sand content

Workability = Low

Max size of aggregate = 20mm

Zone of sand = II

w/c ratio = 0.51

From table the proportion of sand = 33- 39%

= 36% (say)

Sand = 1875x0.36

= 675 kg/m³

Step 8 :- Determination of coarse aggregate

Coarse aggregate = (1875- 675) kg/m³

= 1200 kg/m³

Thus the quantity of materials per cum of concrete on the basis

of saturated and surface dry aggregates:

Water = 180 kg/m³

Cement = 353 kg/m³

Sand = 675 kg/m³

Coarse agg = 1200 kg/m³

Mix ratio by weight on the basis of saturated and surface dry

aggregates:

Cement : Sand : C/aggregate = 1 : 1.91 : 3.40

Water cement rati0 = 0.51

FINAL PROPORTIONS :

CONVERSION OF PROPORTION BY WEIGHT TO PROPORTION BY VOLUME

Proportion by weight can be converted into proportion by

volume, by dividing it with the bulk density of site aggregates.

Bulk density of cement = 1.44 x 103 kg/m³

Bulk density of sand = 1.52 x 103 kg/m³

Bulk density of c/ aggregate = 1.47 x 103 kg/m³

Therefore, mix ratio by volume = 1 : 1.81 : 3.33

Free water cement ratio = 0.51

Working out volume of aggregate for one bag of cement

Cement = 50 kg = 35000cc

Dry sand = 1.81x35000 = 2x(33cm x 33cm x 29cm)

Room dry agg = 3.33x35000 = 4x(32cm x 32cm x 28.5cm)

Free water = 25.5 liter

NOTE : The bulking of sand and adjustment in mixing water

should be taken into consideration as per actual moisture

content of site aggregates.

MIX DESIGN WITH USE OF PLASTICIZER

In Example 1 above , it is proposed to use superplasticizer forreduction in mixing water. It is found that 3cc/kg ofsuperplasticizer reduces 10% of water.

Accordingly, water reqmt = (180-18) Kg/ m³

= 162 Kg/ m³

Cement reqmt = (162/0.51) Kg/ m³

= 318 Kg/ m³

Density of wet concrete = 2430 Kg/ m³

Total aggregate = (2430 – 162 – 318) Kg

= 1950 Kg/ m³

Therefore, Sand = 1950x0.36 = 683 Kg/ m³

C/ aggregate = 1950 – 683 = 1267 Kg/ m³

Superplasticizer = 318x3 = 954 cc/ m³

Quantity of material by volume per bag of cement

Cement = One bag (50 Kg)

Dry sand = 2x( 33cm x 33cm x 32.6cm)

Dry aggregate = 4x( 32cm x 32cm x 33.3cm)

Water = 25.5 lit

Superplasticizer = 150 cc

Saving in cost/cum of concrete

Saving in cement = 353 – 318 = 35 Kg

cost of cement saved = 35x3 = Rs.105

Cost of superplast = Rs. 50

(One liter)

Overall saving = Rs.(105-50) = Rs. 55

(Per cum of concrete)

Thus use of superplasticizer results in saving in cost and otherbenefits such as reduction in mixing water & well compactedbetter finished concrete.