Project on Concrete Mix Design for various grades of Concrete

Challenge @ 5

1. AIM:

To design the concrete mix for M30 grade concrete with fly ash. Data required for concrete mix design:

• Grade of concrete
• Maximum size of aggregate
• Minimum cement content
• Maximum water-cement ratio
• Workability in terms of slump
• Exposure condition
• Maximum temperature at the pouring point
• Early age strength (if required)
• Grading zone of fine aggregate
• Type of aggregate
• Maximum cement content
• Admixture used
• Specific gravity of all the materials
• Moisture content (free)

PROCEDURE:

1. Concrete Mix Design for M35 grade concrete with Fly ash:
2. Target mean strength of concrete f¹_ck

f¹_ck = f_ck + 1.65*S

= 35 + 1.65*5

= 43.25 N/mm²

Where,

f_ck = Characteristic compressive strength at 28 days

S = Standard deviation from [ IS 10262:2009 Table-1]

2. Selection of water-cement ratio

From the, Table-5 of IS 456:2000, It can be taken depending upon the exposure condition

3. Selection of water content

From, Table – 2 of IS 10262:2009,

The maximum water content for 25mm to 50mm slump =186 Kg = 186 Liters

[For additional slump 3% may be added for every 25mm slump]

As super plasticizer is used, the water content can be reduced up to 20% and above.

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

4. Selection of cement content

• It can be calculated from water-cement ratio
• Minimum cement content is taken from table-5 of IS 456:2000

For example:

W=186 kg; Water-cement ratio=0.45

Cement= = = 413.33 Kg

Compare this value with from table-5 of IS 456 minimum cement content

Now, to preparation a mix containing fly ash the following steps are suggested.

Cementitious material content = Cement content * % of cementitious material.

Fly ash cementitious material = Cementitious material * % of fly ash content

Fly ash material content = Cementitious material – Fly ash cementitious content

5. Preparation of volume of coarse aggregate and Fine aggregate

From table-3 of IS 10262:2009; Volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (Zone-I)

• As water-cement ratio is lower by 0.10, the proportion of volume of coarse aggregate is increased by 0.02 (at the rate of -1+0.01 for every ±05 change in w/c ratio)

[NOTE: Is coarse aggregate is not angular type, then also the volume of coarse aggregate may be required to be increased suitability, based experience].

6. Mix Calculations

The mix calculation per unit volume of concrete shall be as follows:

1. Volume of concrete = 1 m³
2. Volume of cement = *
3. Volume of water = *
4. Volume of fly ash = *
5. Volume of aggregate (Coarse aggregate+ Fine aggregate) = [a-(b+c+d)]
6. Mass of coarse aggregate = e * Volume of C.A. * Sp. gravity of C.A. * 1000
7. Mass of fine aggregate = e * Volume of F.A. * Sp. gravity of F.A. * 1000

7. Mix proportion
8. Cement = ………Kg/m³
9. Water = ………Kg/m³
10. Fine aggregate = ………. Kg/m³
11. Coarse aggregate = …... Kg/m³
12. Fly ash = ………. Kg/m³
13. Water-cement ratio = …….

1. Concrete Mix Design for M50 grade concrete without Fly ash:
2. Target mean strength of concrete f¹_ck

f¹_ck = f_ck + 1.65*S

= 50 + 1.65*5

= 58.25 N/mm²

Where,

f_ck = Characteristic compressive strength at 28 days

S = Standard deviation from [ IS 10262:2009 Table-1]

2. Selection of water-cement ratio

From the, Table-5 of IS 456:2000, It can be taken depending upon the exposure condition

3. Selection of water content

From, Table – 2 of IS 10262:2009,

The maximum water content for 25mm to 50mm slump =186 Kg = 186 Liters

[For additional slump 3% may be added for every 25mm slump]

As super plasticizer is used, the water content can be reduced up to 20% and above.

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

4. Selection of cement content

• It can be calculated from water-cement ratio
• Minimum cement content is taken from table-5 of IS 456:2000

For example:

W=186 kg; Water-cement ratio=0.45

Cement= = = 413.33 Kg

Compare this value with from table-5 of IS 456 minimum cement content

5. Preparation of volume of coarse aggregate and Fine aggregate

From table-3 of IS 10262:2009; Volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (Zone-I).

• As water-cement ratio is lower by 0.10, the proportion of volume of coarse aggregate is increased by 0.02 (at the rate of -1+0.01 for every ±05 change in w/c ratio)

[NOTE: Is coarse aggregate is not angular type, then also the volume of coarse aggregate may be required to be increased suitability, based experience].

6. Mix Calculations

The mix calculation per unit volume of concrete shall be as follows:

1. Volume of concrete = 1 m³
2. Volume of cement = *
3. Volume of water = *
4. Volume of admixture = *
5. Volume of aggregate (Coarse aggregate+ Fine aggregate) = [a-(b+c+d)]
6. Mass of coarse aggregate = e * Volume of C.A. * Sp. gravity of C.A. * 1000
7. Mass of fine aggregate = e * Volume of F.A. * Sp. gravity of F.A. * 1000
8. Mix proportion
9. Cement = ………Kg/m³
10. Water = ………Kg/m³
11. Fine aggregate = ………. Kg/m³
12. Coarse aggregate = …... Kg/m³
13. Admixture = ………. Kg/m³
14. Water-cement ratio = …….

RESULT:

By adding the all the values on the above design, we can get the ratio of the mix design. In this question they couldn’t give the proper data for calculation and design of the mix.