Project on Concrete Mix Design for various grades of Concrete

AIM: Illustrating the mix proportion for a mix of M35 grade of concrete using flyash conforming to IS 3812 (PART 1) as specified in IS 10262: 2009

INTRODUCTION : Here comes the assumption for proceeding towards MIX DESIGN:

1. Grade Designation : M 40
2. Type OF cement : OPC Grade 43 conforming to IS 8112
3. TYpe of mineral admixture : Fly ash conforming to IS 3812 (PART 1)
4. MAXIMUM nominal size of aggregate : 20mm
5. minimum/ maximum cement content : 320/ 450 kg / m^3
6. maximum water cement ratio: 0.45
7. Workability : 100 mm
8. Exposure Condition : Severe ( FOr reinforced concrete)
9. Method of concrete placing : Pumping
10. Degree of Supervision : Good
11. Type of Aggregate : Crushed aggregate
12. Chemical Admixture type : Superplasticizers conforming to IS 3812(PART 1)

PROPRETIES of above mentioned aggregate are as follows:

1. Cement used: OPC 43 Grade
2. Specific Gravity of Cement : 3.15
3. Flyash: Conforming to IS 3812
4. specific gravity of flyash 1: 2.2
5. Specific Gravity of

• Coarse aggregate : 2.7
• fine aggregate :2.75

6. Water Absorption :

• Coarse aggregate : 0.5%
• Fine aggregate : 1%

7. Free SUrface MOisture :

• Coarse aggregate : nil
• fine aggregate : nil

8. Sieve Analysis :

• coarse aggregate

IS SIEVE sizes (mm)	analysis of coarse (1)	aggregate fraction (2)	% of (1)	different fraction(2)	combined (1+2)
20	100	100	60	40	100
10	0	71.2		28.5	28.5
4.75		9.4		3.7	3.7
2.36		0

conforming to table 2of IS 383.

• FINE aggregate :conforming to grading zone1 of table 4 of IS 383.

PROCEDURE :

1. mean characteristic strength(fm) : in order to have not MORE(i.e. not more than 5 out of 100 samples) than specified proportions of test samples below the characteristic strength, we go for higher compressive strength named as mean compresseive strength.

fm = fck +1.65 s

= 35 + (1.65*5)= 43.25 N/mm^2

B. water/ cement ratio:

1. from table 5 of is 456:2000 maximum w/c ratio = 0.45 for severe exposure condition.
2. from graph of mean compressive strength vs free water cement ratio obtained for given sample of aggregate
3. from graph of 28 days compressive strength of concrete vs water cement ratio on basis of 7 days strngth of cement categorised into 7 categories as A, B, C, D, E, F, G

MINIMUM Of above three values will be minimum w/c ratio.

here we assume it as 0.4

C. WATER CONTENT :

From Table 2 of IS 10262: 2009, maximum water content of 20 mm aggregate= 186 litre(for 25-50 mm slump)

Estimated water content for 100 mm slump =186 +(6/100)*186 = 197 litrs

as SUPERPLASTICIZERS is used, based on trials with superplasticizers water content reduction of 29% has been achieved.

hence water content on trial basis = 0.71* 197= 140 litres

D. CEMENT CONTENT :

W/C RATIO= 0.4

CEMENT contnt =140/0.4= 350 kg/ m^3

From TABLE 5 of IS456: 2000 minimum cement content for reinforced structure exposed to severe condition is = 320kg/m3

maximum of two will be our answer= 350 kg/m3.

now, assuming incresre in CEmentitious material content to be 10%

CEmentitious material content : 350*1.1=385 kg/m3.

water content =140 kg/m3.

w/c ratio= 140/385 =0.364

based on experience & trials , we are deciding/ assuming flyash content to be 30% of cememtitious content=

0.3*385= 115 kg/m3.

cement requirement= 385-115 = 270kg/ m3.

cement saving will be = 350-270= 80kg/m3.

flyash utilised will be = 115 kg/m3.

E. PROPORTIONS OF VOLUME OF COARSE AGGREGATE & FINE AGGREGATE CONTENT :

baesd on table 3 of IS 10262: 2009, VOLUME of coarse aggregate to 20mm size aggregate & fine aggregate (ZONE 1) for water cement ratio(0.5)=0.6

in the present case , w/c ratio comes out to be =0.364.

volume of coarse agg. is to be incresesd to decrease the fine aggregate content. AS the w/c ratio is decresed by 0.136 , there will be increse in coarse aggregate proportion by 0.0272.(for +/- 0.05 change in w/c ratio , -/+ change in 0.01 coarse aggregate proportion will occur).

hence coarse aggregate proprtion will be= 0.627

for pumpable concrete, values of coarse aggregate proportion can be decreased upto 10%.

therefore, coarse aggregate proportion will be = (0.9* 0.627) =0.565

fine aggregate proportions = 1-0.565=0.435

F. MIX CALCULATIONS:

1. Volume of concrete= 1 cum
2. vOLUME of cememt = 270/3.15*(1/1000)= 0.086 cum
3. volume of fly ash= 115/2.2*(1/1000)= 0.052 cum
4. volume of water = 140/1000=0.14 cum
5. volume of chemical admixture (@ 2% of total cementitious material by mass )= 7.7/1.145*(1/1000)=0.00672 cum
6. volume of aggregate will be= 1-(0.086+.052+.14+0.0067)=0.715 cum
7. coarse aggregate proprtion = 0.565*0.7150=0.404cum
8. fine aggregate =0.435*0.715= 0.311 cum.
9. weight of coarse aggregate = 0.404*2.7*1000=1091 kg/m3
10. weight of fine aggregate = 0311 *2.74*100=853 kg/m3

RESULT: MIX PROPORTION WILL BE

WEIGHT OF CEMENT : FINE AGGREGATE: COARSE AGGREGATE= 385:853:1091

1 : 2.215 : 2.833.

WEIGHT OF CEMENT utilised= 270kg/m3

weight of fly ash =115 kg/m3

weight of water= 140 kg/m3

weight of superplasticizers= 7.7 kg/m3

weight of coarse agg.=1091 kg/m3

weight of fine aggregate = 853 kg/m3.

water cement ratio adopted =0.364

• keeping the water cement ratio same, trial the mixes with change in admixture or water content to get the desired slump value .
• plot the graph with +/- 10% change in w/c ratio vs mean compressive strength of concrete.

AIM: ILLUSTRATE concrete mix design for M50 grade as specified in IS 10262: 2009 ALONG with the support of IS 456:2000.

INTRODUCTION: Here are the assumption to be followed for solving the mix design calculation

1. Grade Designation : M 50
2. Type OF cement : OPC Grade 43 conforming to IS 8112
3. MAXIMUM nominal size of aggregate : 20mm
4. minimum/ maximum cement content : 320/ 450 kg / m^3
5. maximum water cement ratio: 0.45
6. Workability : 100 mm
7. Exposure Condition : Severe ( FOr reinforced concrete)
8. Method of concrete placing : Pumping
9. Degree of Supervision : Good
10. Type of Aggregate : Crushed aggregate
11. Chemical Admixture type : Superplasticizers conforming to IS 3812(PART 1)

PROPRETIES of above mentioned aggregate are as follows:

1. Cement used: OPC 43 Grade
2. Specific Gravity of Cement : 3.15
3. specific gravity of admixture : 1.145
4. Specific Gravity of

• Coarse aggregate : 2.7
• fine aggregate :2.74

6. Water Absorption :

• Coarse aggregate : 0.5%
• Fine aggregate : 1%

7. Free SUrface MOisture :

• Coarse aggregate : nil
• fine aggregate : nil

8. Sieve Analysis :

• coarse aggregate

IS SIEVE sizes (mm)	analysis of coarse (1)	aggregate fraction (2)	% of (1)	different fraction(2)	combined (1+2)
20	100	100	60	40	100
10	0	71.2		28.5	28.5
4.75		9.4		3.7	3.7
2.36		0

conforming to table 2of IS 383.

• FINE aggregate :conforming to grading zone1 of table 4 of IS 383.

PROCEDURE:

A. MEAN COMPRESSIVE STRENGTH:

in order to have not MORE(i.e. not more than 5 out of 100 samples) than specified proportions of test samples below the characteristic strength, we go for higher compressive strength named as mean compresseive strength.

fm= fck+ 1.65 s

= 50 + (1.65*5)=58.25 N/mm2.

B. WATER CEMENT RATIO:

• from table 5 of IS 456:2000, maximum w/c ratio for severe exposure condition for reinforced structure will be=0.45
• FROM the graph of mean compressive strenght vs free water cement ratio based on trial mixes for given material / aggregate
• from the graph of 28 days compressive strength of concrete vs water/cement ratio based on 7 days compressive strength of cement categorised into 7 category as A,B,C,D,E,F& G.

MINIMUM OF THREE ABOVE will be our water cement ratio.

adopting w/c ratio =0.4( based on experience & trial)

C. CALCULATION OF WATER CONTENT:

FROM TABLE 2 OF IS 10262: 2009 on page 3, give the approximate value of water content based on maximum size of aggregate used. this content is used only for trial mixes starting point.

S.NO.	MAXIMUM SIZE OF AGGREGATE	WATER CONTENT REQUIREMENT(KG)
1	10	208
2	20	186
3	40	165

WATER REQUIREMENT FOR 100mm slump = 186 +(6/100)*186=197 kg

based on superplasticizers used, water reduction could be achieved upto 20% or above.

assuming water content reduction to be 25% then water required will be = 0.75*197=147.75=~148 kg/m3

D. CALCULATION OF CEMENT CONTENT:

W/C RATIO= 0.4

water content =148 kg/m3

cememt rqd.= 148/0.4=370 kg/m3

from table 5 of IS 456:2000 ON PAGE NO. 20, minimum cement content for severe exposure condition in reinforced structure will be = 320 kg/m3.

adopted higher value ,i.e. 370 kg/m3 cement content.

E. ESTIMATION OF COARSE AGGREGATE PROPORTION IN TERMS OF TOTAL VOLUME OF AGGREGATES:

baesd on table 3 of IS 10262: 2009, VOLUME of coarse aggregate to 20mm size aggregate & fine aggregate (ZONE 1) for water cement ratio(0.5)=0.6

in the present case , w/c ratio comes out to be =0.4 .

volume of coarse agg. is to be incresesd to decrease the fine aggregate content. AS the w/c ratio is decresed by 0.136 , there will be increse in coarse aggregate proportion by 0.02.(for +/- 0.05 change in w/c ratio , -/+ change in 0.01 coarse aggregate proportion will occur).

hence coarse aggregate proprtion will be= 0.62

for pumpable concrete, values of coarse aggregate proportion can be decreased upto 10%.

therefore, coarse aggregate proportion will be = (0.9* 0.62) =0.56

fine aggregate proportions = 1-0.56=0.44

F. MIX CALCULATION:

1. volume of concrete = 1 cum
2. volume of cement used = 370/3.15*(1/1000)= 0.1175cum
3. volume of water used= 148/1000= 0.148 cum
4. volume of admixture (2% superplasticizers of total cementitious material) = (7.4/1.145)= 0.00646 cum
5. volume of aggregate = 1-(0.1175+0.148+.00646)= 0.73 cum
6. volume of coarse aggregate = 0.56* 0.73=0.409 cum
7. volume of fine agg.= 0.44* 0.73= 0.321 cum
8. weight of coarse aggregate = 2.7*1000*0.409= 1104.3 kg/ m3
9. weight of fine aggregate= 2.74 * 1000*0.321= 880 kg/m3.

RESULT:

weight of cement : fine aggregate; coarse aggregate= 370:880:1104.3=

1 : 2.38 : 2.98

WEIGHT OF CEMENT utilised= 370kg/m3

weight of water= 148 kg/m3

weight of superplasticizers= 7.4 kg/m3

weight of coarse agg.=1104.3 kg/m3

weight of fine aggregate = 880kg/m3.

water cement ratio adopted =0.4

• keeping the water cement ratio same, trial the mixes with change in admixture or water content to get the desired slump value .
• plot the graph with +/- 10% change in w/c ratio vs mean compressive strength of concrete.