Project on Concrete Mix Design for various grades of Concrete

Aim : Mix design for M 35 grade concrete with fly ash

Step 01 : Stipulation's for proportioning :-

A -	Grade designation	M35
B -	Type of cement	OPC 43 grade conforming to IS 8112
C -	Type of mineral admixture	Fly ash confirming to IS 3812 ( Part 1)
D -	Maximum nominal size of aggregates	20 mm
E -	Minimum cement content	320 kg/m^3 (Table :5 IS 456-2000,based on exposure condition)
F -	Maximum water-cement ratio	0.45 (Table :5 IS 456-2000,based on exposure condition)
G -	Workability	100 mm slump value of pumpable concrete
H -	Exposure condition	Severe ( for reinforced concrete)
I -	Method of concrete placing	Pumping
J -	Degree of supervision	Good
K -	Type of aggregate	Crushed angular aggregate
L -	Maximum cement content	450 kg/m^3
M -	Chemical admixture type	Superplaticizer

Step 02 : Test data for materials :-

A -	Cement used	OPC 43 grade confirming to IS 8112
B -	Specific gravity of cement	3.15
C -	Fly ash	Conforming to IS 3812 part 1
D -	Specific gravity of flyash	2.2
E -	Chemical admixture	Superplaticizer conforming to IS 9103
F -	Specific gravity of : Coarse aggregate Fine aggregate	2.74 2.74
G -	Water absorption : Coarse aggregate Fine aggregate	0.5% 1%
H -	Free surface moisture : Coarse aggregate Fine aggregate	Nil Nil
I -	Seive analysis : Fine aggregate Coarse aggregates	Conforming to grading Zone 1 of table 4 IS 383 Table

Step 03 : Target strength for mix proportioning :-

Target mean strength

f'ck = fck +1.65s

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

Where,

f'ck - Target average compressive stength at 28 Days

fck - Characteristic compressive strength

s- Standard deviation

Step 04 : Selection of Water Cement Ratio :-

Maximum water-cement ratio = 0.45 (for severe condition ,from table 5 of IS 456-2000)

On experience water-cement ratio = 0.4

0.4 < 0.45, Hence OK.

Step 05 : Selection of water content :-

Maximum water content for 20mm aggregate =186 litres ( Table 2 of IS 1026:2009) for 25mm to 50mm slump range

For 100 mm slump

= 186+(6/100)*186 =197 litres

As superplaticizer is used, the water content is reduced upto 30%

Based on trials water content reduction of 29% is achieved with plasticizer

Hence arrived water content = 197*0.71 = 140 litres

Step 06 : Calculated of Cement content :-

Water - cement ratio = 0.4

Cementitious material ( Cement + flyash ) content = 140/0.4 = 350 kg/m^3

In table 5 of IS 456-2000, the cement content for severe exposure = 320kg/m^3

350 kg/m^3 > 320kg/m^3

Hence OK.

Now,

To proportion the mix containing flyash the following steps are suggested :

1. The percentage of flyash need to be decided based on project requirement and qualityof materials.
2. In some cases increase in cementatious materials can be warrned. Increase in cementatious material content and its percentage may be based on experience and trial In this increase of 10% cementatious material content is considered.

Cementatious material content	350*1.1 = 385kg/m^3
Water content	140kg/m^3
So, water- cement ratio	140/385 =0.364
Fly ash at 30% total cementatious material content	385-30% =115kg/m^3
Cement (OPC)	385-115 =270kg/m^3
Saving of cement while using flyash	350-270=80kg/m^3
Fly ash beign utilized	115kg/m^3

Step 07 : Proportion of volume of Coarse Aggregate And Fine Aggregate :-

From table 3 of IS 1026:2009 ,volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone 1) for water - cement ratio = 0.6

In present case the water - cement ratio is 0.4

Therefore the volume of coarse aggregate needs to be increased to decrease the fine aggregate content.

As the water- cement ratio is lowered by 0.1 ,the proportion of volume of coarse aggregate is increased by 0.02( at the rate of +/- 0.01 for every +/- 0.05 change in water- cement

ratio)

Hence the corrected value ofcoarse aggregate for the water-cemnt ratio = 0.64

( If coarse aggregate is not of angular type, then also the volume of coarse aggregate may be required to be increased suitably ,based on experience)

For pumpable concrete, these are reduced by 10 %

Volume of coarse aggregate = 0.64*0.9 = 0.576

Volume of fine aggregate = 1-0.576 = 0.424

Step 08 : Mix Calculations :-

A -	Volume of concrete	= 1 m^3
B -	Volume of cement = (Mass of cement / Specific gravity of cement) * 1/1000	= (270/3.15 )*1/1000 = 0.086m^3
C -	Volume of flyash = (Mass of flyash / Specific gravity of flyash) * 1/1000	= (115/2.2) *1/1000 = 0.052m^3
D -	Volume of water = (Mass of water / Specific gravity of water) * 1/1000	= (140/1)*1/1000 = 0.140m^3
E -	Volume of chemical admixture = (Mass of admixture / specific gravity of admixture) * 1/1000	= ( 7.6/1.14)*1/1000 = 0.006m^3
F -	Volume of aggregate (Fine and coarse) = a - (b+c+d+e)	= 1-(0.086+0.052+0.140+0.006) = 0.716m^3
G -	Mass of coarse aggregate = f * Volume of coarse aggregate * Specific gravity of coarse aggregate * 1000	= 0.716*0.576*2.74*1000 = 1130 kg/m^3
H -	Mass of fine aggregate = f * Volume of fine aggregate * Specific gravity of fine aggreate * 1000	= 0.716*0.424*2.74*1000= 831 kg/m^3

Step 09 : Mix Proportion :-

Cement	270kg/m^3
Fly ash	115kg/m^3
Water	140kg/m^3
Fine aggregate	831kg/m^3
Coarse aggregate	1130kg/m^3
Chemical admixture	7kg/m^3
Water- cement ratio	0.364
MIX RATIO	1:2.15:2.94

Step 10 :

The slump shall be measured and the water content and dosage of admixyure shall be adjusted for achieving the required slump on trial.The mix proportion shall be reworked for the actual water content and checkedd for durability requirements.

Step 11 :

Two or more trials having variation of 10 % of water-cement ratio in Clause 10(Step 10) shall be carried out and a graph between three water - cement ratios and corresponding strengths shall be plotted to work out the mix proportions for the given target strength for feild trials .However durability shall be met.

Result : The mix design for M 35 grade of concrete with flyash is 1: 2.15:2.94

* Calculate the Concrete Mix Design for M50 grade concrete without Fly ash *

Aim : Mix design of M 50 grade concrete

Step 01 : Stipulation's for proportioning :-

A -	Grade designation	M50
B -	Type of cement	OPC grade 43 conforming to IS 8112
C -	Maximum nominal sizeof aggregate	20mm
D -	Minimum cement content	320kg/m^3
E -	Maximum water-cement ratio	0.45 (Table :5 IS 456-2000,based on exposure condition)
F -	Workability	100mm ,slump value of pumpable concrete
G -	Exposure condition	Severe (for reinforced concrete)
H -	Method of concrete placing	Pumping
I -	Degree of supervision	Good
J -	Type of aggregate	Crushed angular aggregate
K -	Maximum cement content	450kg/m^3
L -	Chemical admixture type	Superplaticizer

Step 02 : Test data for materials :-

A -	Cement used	OPC 43 grade confirming to IS 8112
B -	Specific gravity of cement	3.15
C -	Chemical admixture	Superplaticizer conforming to IS 9103
D -	Specific gravity of Coarse aggregate Fine aggregate	2.74 2.74
E -	Water absorption Coarse aggregate Fine aggregate	0.5% 1%
F -	Free surface moisture Coarse aggregate Fine aggregate	Nil Nil
G -	Seive analysis Fine aggregate Coarse aggregate	Conforming to grading Zone 1 of table 4 IS 383 Table

Step 03 : Target strength for mix proportioning :-

Target mean strength,

f'ck =fck +1.65s

= 50+1.65*5 =58.25 N/m^2

Where,

f'ck - Target average compressive stength at 28 Days

fck - Characteristic compressive strength

s- Standard deviation

Step 04 : Selection of Water Cement Ratio :-

From Table :5 of IS 456-2000, by exposure condition

Here severe condition is considered , Maximum water-cement ratio= 0.45

Based on experience water- cement ratio = 0.4

0.4 <0.45 ,Hence OK.

Step 05 : Selection of water content :-

Maximum water content for 20mm aggregate = 186 litres ( Table 2 of IS 1026:2009) for 25mm to 50mm slump range

For 100 mm slump ,= 186+(6/100)*186 = 197 litres

As superplaticizer is used, the water content is reduced upto 30%

Based on trials water content reduction of 29% is achieved with plasticizer

Hence arrived water content = 197*0.71 = 140 litres

Step 06 : Calculated of Cement content :-

Water - cement ratio = 0.4

Cement content = 140/0.4 =350kg/m^3

In table 5 of IS 456-2000, the cement content for severe exposure = 320kg/m^3

350kg/m^3 > 320kg/m^3

Hence OK.

Step 07 : Proportion of volume of Coarse Aggregate And Fine Aggregate :-

From table 3 of IS 1026:2009 ,volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone 1 ) for water- cement ratio = 0.6

In present case the water - cement ratio is 0.4

Therefore the volume of coarse aggregate needs to be increased to decrease the fine aggregate content .

As the water- cement ratio is lowered by 0.1 ,the proportion of volume of coarse aggregate is increased by 0.02( at the rate of +/- 0.01 for every +/- 0.05 change in water- cement ratio)

Hence the corrected value of coarse aggregate for the water-cemnt ratio = 0.64

( If coarse aggregate is not of angular type, then also the volume of coarse aggregate may be required to be increased suitably ,based on experience )

For pumpable concrete, these are reduced by 10 %

Volume of coarse aggregate = 0.64*0.9 = 0.576

Volume of fine aggregate = 1-0.576 = 0.424

Step 08 : Mix Calculations :-

A -	Volume of concrete	= 1 m^3
B -	Volume of cement = ( Mass of cement / Specific gravity of cement ) * 1/1000	= (350/3.15)*1/1000 =0.111 m^3
C -	Volume of water = ( Mass of water/ Specific gravity of water ) * 1/1000	= (140/1)*1/1000 =0.140 m^3
D -	Volume of chemical admixture = ( Mass of admixture/Specific gravity of admixture ) * 1/1000	= (7.6/1.145)*1/1000 =0.006 m^3
E -	Volume of agggregate (fine adn coarse) = a-(b+c+d)	= 1-(0.111+0.140+0.006) =0.743 m^3
F -	Mass of coarse aggregate = e * Volume of coarse aggregate * Specific gravity of coarse aggregate * 1000	= 0.743*0.576*2.74*1000= 1173 kg/m^3
G -	Mass of fine aggregate = e * Volume of fine aggregate * Specific gravity of fine aggregate * 1000	= 0.743*0.424*2.74*1000 =863 kg/m^3

Step 09 : Mix Proportion :-

Cement	350kg/m^3
Water	140kg/m^3
Fine aggregate	863kg/m^3
Coarse aggregate	1173kg/m^3
Chemical admixture	7kg.m^3
Water cement ratio	0.4
MIX RATIO	1: 2.46: 3.35

Step 10 :

The slump shall be measured and the water content and dosage of admixyure shall be adjusted for achieving the required slump on trial.The mix proportion shall be reworked for the actual water content and checkedd for durability requirements.

Step 11 :

Two or more trials having variation of 10 % of water-cement ratio in Clause 10(Step 10) shall be carried out and a graph between three water - cement ratios and corresponding strengths shall be plotted to work out the mix proportions for the given target strength for feild trials .However durability shall be met.

Result : The mix ratio for M 50 grade concrete is 1:2.46:3.35

* In this calculation's aren used Table's *

1 . Table 8 of IS 10262 : 2009

Note :- (+ 1 N/mm^2 where there is deviation,when not periodically checked for workability and strength )

2. Table 5 of IS 456 : 2000

3 . Table :2 of IS 10262 : 2009

4 . Table 3 IS 1026 : 2009

Note :- ( Volume of coarse aggregate per unit volume of total aggregate for different zones of fine aggregate )