Project on Concrete Mix Design for various grades of Concrete

AIM -

It is important to note that concrete is a heterogeneous material containing a variety of ingredients, such as coarse aggregates, fine aggregates, water, admixtures, and so on. This gives concrete the strength it needs to achieve the desired result, and they must be included in the specified amount in order to achieve this result. This specific amount is decided based on the mix design as per the IS code 10262:2019. A specific amount of concrete is selected to ensure that it gives the desired workability in the plastic state, the desired durability in the given environmental conditions, the desired strength in the hardened state, as well as the most economical concrete possible.

INTRODUCTION :-

There are two different concrete mix designs in this project.

1. The M35 concrete mix design

Fly ash, superplasticizer, and wet aggregates are used to create the M35 concrete mix design.

2. M50- Grade concrete mix design

In order to create the M50 concrete mix design, superplasticizer and partly dry aggregates are used.

TO DETERMINE THE MIX DESIGN OF M35 CONCRETE MIX WITH FLY ASH

• Classification: M35
• OPC 43 grade verifying IS 12269 cement type
• Fly ash is the type of mineral additive.
• The aggregate's maximum nominal size is 20.
• (Table 5 of IS 456:2000) Minimum water-to-cement ratio: 0.45
• Workability: Slump of 100–120mm

MATERIAL PROPERTIES

• Use of OPC 43 grade (IS 12269) cement
• Cement's specific gravity is 3.15.
• Specific gravity of fly ash is 2.2.
• Aggregate that is coarse- Specific gravity: 2.74
• Water absorption of coarse aggregate: 0.5%
• water absorption of fine aggregate: 2.74 fine aggregate specific gravity
• Sieve analysis of coarse aggregate according to IS 383 Table 2
• Sieve analysis of fine aggregate in accordance with Grading zone I of Table 4 of IS 383

PROCEDURE

• The formula f'ck = fck + 1.65s yields the target strength for the mix percentage (Table I: IS 10262:2009).

assuming that s = 5N/sq-mm.

F'ck thus equals 35+1.65(5) = 43.25 N/sq- mm. Maximum

• water-cement ratio = 0.4 is taken into account (Table 5: IS 456:2000).
• moisture content
  (Table 2: IS 10262:2009) Maximum water content for 20 mm aggregate is 186 litres.

Water content for a 100mm slump is estimated at 186+ (6/186) = 197 litres.

However, the water content can be decreased by 20% to 30% if super plasticizer is used.

This results in a water content of 132 litres (197-(30% of 197)).

Use 140 litres.

• Adopted cement content to volume ratio is 0.4.

140 divided by 0.4 is 350 kg/cum of cement.

For moderate exposure, cement must contain a minimum of 320 kg/cum. (2000) (Table 5: IS 456

350 kg/cume exceeds 320 kg/cum.

• Fly ash content: Taking a 10% increase in cementitious material into consideration

Cementitious content is therefore 350 x 1.1 = 385 kg/cum.

Fly ash makes for 30% of the cementitious material overall, or 385 x 0.3, or 115 kg/cum.

• Volume of coarse aggregate and fine aggregate with a w/c ratio of 0.5 = 0.6 (Table 3: IS 10262:2009) is the proportion of the two.

CALCULATION

The calculations for the blend are as follows:

• Concrete volume equals one cum.
• Volume of cement is equal to Mass of cement divided by (Sp. gravity times 1000) = 270/(3.15 times 1000) = 0.086 cum.
• Volume of fly ash is equal to Mass of fly ash / (Sp. gravity x 1000) = 115/(2.2x1000) = 0.052 cum.
• Volume of water is equal to mass of water divided by (Sp. gravity times 1000) = 140/(1x1000) = 0.14 cum.
• Volume of chemical admixture is calculated as Mass of chemical admixture/(Sp. gravity x 1000) = 7.6/(1.145x1000) = 0.006cum.
• All together, the volume equals [1-(0.086+0.052+0.14+0.006)] = 0.716 cum.
• Mass of coarse aggregate is Volume of all aggregates multiplied by Volume of coarse aggregate and Sphericity of coarse aggregate multiplied by 1000, or 0.716x0.56x2.74x1000, or 1098 kg/cum.
• Mass of fine aggregates is calculated as follows: 0.716x0.44x2.74x1000 = 863 kg/cum. Vol. of all aggregates x Vol. of fine aggregate x Sp. gravity of fine aggregates x 1000.

RESULTS

• Mixing ratio attained:
• Cumulus weight = 270 kg.
• 115 kg/cum for fly ash
• 140 litres of water
• 863 kg/cum for fine aggregates.
• 1098 kg/cum for coarse aggregate.
• Admixture of chemicals = 7 kg/cum.
• w/c ratio equals 0.4
• Weight-based mixture ratio: 1:2.24:2.85

CONCLUSION

It is necessary to measure the slump and adjust the water content and admixture in order to achieve the desired slump. In order to meet the requirements, the proportions of the mix can be adjusted and reworked as necessary

To determine the mix design for M50 concrete

• Classification: M50
• OPC 43 grade verifying IS 12269 cement type
• The aggregate's maximum nominal size is 20.
• (Table 5 of IS 456:2000) Minimum water-to-cement ratio: 0.45
• Workability: Slump of 100–120mm

MATERIAL PROPERTIES

• Use of OPC 43 grade (IS 12269) cement
• Cement's specific gravity is 3.15.
• Specific gravity of a chemical admixture: 1.145
• Specific gravity of coarse aggregate is 2.74.
• Water absorption of coarse aggregate: 0.5% water
• absorption of fine aggregate: 2.74 fine aggregate specific gravity
• Sieve analysis of coarse aggregate according to IS 383 Table 2
• Sieve analysis of fine aggregate in accordance with Grading zone I of Table 4 of IS 383

PROCEDURE

• The formula f'ck = fck + 1.65s yields the target strength for the mix percentage (Table I: IS 10262:2009).

assuming that s = 5N/sq-mm.

So, f'ck is equal to 50+1.65(5), or 58.25 N/sq-mm.

• Maximum water-cement ratio = 0.4 is taken into account (Table 5: IS 456:2000).
• moisture content

(Table 2: IS 10262:2009) Maximum water content for 20 mm aggregate is 186 litres.

Water content for a 100mm slump is estimated at 186+ (6/186) = 197 litres.

However, the water content can be decreased by 20% to 30% if super plasticizer is used.

• This results in a water content of 132 litres (197-(30% of 197)).

Use 140 litres.

• Adopted cement content to volume ratio is 0.4.

140 divided by 0.4 is 350 kg/cum of cement.

For moderate exposure, cement must contain a minimum of 320 kg/cum. (2000) (Table 5: IS 456

350 kg/cume exceeds 320 kg/cum.

• Volume of coarse aggregate and fine aggregate with a w/c ratio of 0.5 = 0.6 (Table 3: IS 10262:2009) is the proportion of the two.

As a result, the amount of coarse aggregate with a w/c ratio of 0.4 is rectified to 0.62.

For concrete that can be pumped, it can be cut by up to 10%. So, the volume of coarse aggregate is equal to 0.62 x 0.9, or 0.56.

Volume of fine aggregate is equal to 0.44 x 1.056.

CALCULATIONS

The calculations for the blend are as follows:

• Concrete volume equals one cum.
• Volume of cement is equal to Mass of cement divided by (Sp. gravity times 1000) = 350/(3.15x1000) = 0.111 cum.
• Volume of water is equal to mass of water divided by (Sp. gravity times 1000) = 140/(1x1000) = 0.14 cum.
• Volume of chemical admixture is calculated as Mass of chemical admixture/(Sp. gravity x 1000) = 7.6/(1.145x1000) = 0.006cum.
• The total volume is equal to [1-(0.111+0.14+0.006)] = 0.743 cum.
• Mass of coarse aggregate is calculated as follows: 0.743x0.56x2.74x1000 = 1140 kg/cum. Vol. of all aggregates x Vol. of coarse aggregate x Sp. gravity of coarse aggregates x 1000.
• Mass of fine aggregates is calculated as follows: 0.743x0.44x2.74x1000 = 896 kg/cum. Vol. of all aggregates x Vol. of fine aggregate x Sp. gravity of fine aggregates x 1000.

RESULTS

• Mixing ratio attained:
• 350 kg/cum for cement.
• 140 litres of water
• 896 kg/cum for fine aggregates.
• Granular material: 1140 kg/cum.
• Admixture of chemicals = 7 kg/cum.
• w/c ratio equals 0.4
• Weight-based mixture ratio: 1:2.56:3.26

CONCLUSIONS

In order to achieve the desired slump, the water content and admixture can be adjusted in accordance with the slump measurement. A mix proportion can be adjusted and reworked according to the needs of the project.