Project on Concrete Mix Design for various grades of Concrete

Project on Concrete Mix Design for various grades of Concrete

Requirements and Explanations of the Project

1. Aim & Introduction Need to provide the Aim and Introduction of the project in detail (Maximum Marks 50)
2. Procedure in detail Show and explain the step-by-step procedure involved (Maximum Marks 150)
3. Result Explanation of the result needs to be provided (Maximum Marks 60)
4. Report Format Presentation should be well formatted and neat (Maximum Marks 40)

Objectives:

1. Calculate the Concrete Mix Design for M35 grade concrete with fly ash.

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

Introduction:

• Concrete is a composite material made with the right mix proportion and gives good strength and durability and if it is not then gives an adverse effect on concrete properties.
• Mix design of concrete is an efficient process of selecting an economical, relative proportion of material, which gives the amount of work for full compaction.
• Selection of suitable proportions for making concrete of essential strength, durability, and workability.
• Concrete compressive strength depends on the quality and quantity of cement water aggregate, and also depends on the batching, mixing, transportation, placing, compaction, and curing that directly affect the construction.

Nominal mix: In the previous study of nominal mix specification of concrete defined the proportion of ingredients (cement: sand: aggregate). The mixes of fixed cement-aggregate ratio which ensure the strength are termed nominal mixes. It is used for small works. It has limited work for below the M20 grade of concrete. It needs high cement content. Due to the variability of mix proportions, the nominal concrete for given workability varies in strength The Mix proportion like 1:1:2, 1:1.5:3, 1:2:4, etc should be preferred as per the IS Code 456:2000 the nominal mix of concrete.

Standard Mix: The nominal mixes of fixed cement-aggregate ratio (by volume) vary widely in strength and may result in under or over-rich mixes. For this reason, the minimum compressive strength has been included in many specifications. These mixes are termed standard mixes known as standard mixes. As per the code IS 456-2000 concrete mix designated as grade M10, M15, M20, M25 under the 28 days characteristic strength of concrete.M10, M15, M20 and M25 proportion should be (1:3:6, 1:2:4, 1:1.5:3 and 1:1:2).

Design Mix: The structural engineer has proposed the design mix in form of mix proportion which is determined by the concrete producer. The method of results in the production of concrete with the most economically suitable properties In the mix design does not serve as a guide. it does not guarantee the correct mixing ratio for the prescribed performance which does not increase 30 N/mm2. For example, M20 and M25. etc.

Several National and International codes are included in the guidelines for the Mix design:

As per the IS code: Propositioning guidelines – IS 10262:2009,10262:2019 and recommended guideline- IS 10262:1982

As per the BS code: (British standard- BS- EN 206-1 and for complementary standards BS 8500 part 1 & 2)

As per the ACI American Concrete Institute: (American standard – ACI 211, 211-91, reapproved 2002).

Material property of the fresh concrete and then construction should start upon the design.

For Cement, we have tested: Grade of cement, Consistency of cement, Initial setting time, and Specific gravity of cement. For Aggregate we have tested: The density of aggregate, Bulking of fine aggregate, specific gravity of fine aggregate and coarse aggregate, fineness modulus, the Particle size of aggregate, silt content, specific gravity, water absorption tests, and unit weight.

---------------------------------------------------------------------------------------------------------------------------

Objective 1 Calculate the Concrete Mix Design for M35 grade concrete with fly ash

General: Design mix concrete is a process of selecting ingredients for a concrete mixture and deciding on their proportions. The step-by-step process of the mixed grade of concrete has been explained below with using the various Indian Standard codes.

1. Stipulating for Proportioning:

Garde of concrete = M35

Grade or type of cement = OPC 43 grade conforming to IS 8112

Type of mineral admixture: fly ash conforming to IS 3812(PART1)

Maximum nominal size of aggregate = 20mm

Exposure condition: severe (for RCC)

Minimum cement content = 320 kg/m^3 (table 5 from IS 456-2000 code – Exposure condition = severe)

Maximum water cement content = 0.45 (table 5 from IS 456-2000 code – Exposure condition = severe)

Workability =75mm

Method of placing concrete = for pumpable concrete

Type of aggregate: crushed angular aggregate

Maximum cement content: 450 kg/m^3

Degree of supervision = good

Type of aggregate: crushed angular aggregate

Chemical admixture = superplasticizer

2. Test data for materials: the test data obtained from the vendor or producer of the material which are required.

Cement used: = OPC 43 grade conforming to IS 8112

The specific gravity of cement = 3.15

Fly ash: conforming to IS 3812(PART1)

The specific gravity of fly ash =2.2

Chemical admixture: superplasticizer from code IS 9103

The specific gravity of aggregate: coarse aggregate =2.74, and fine aggregate =2.74

Water absorption: coarse aggregate =0.5%, and fine aggregate =1.0%

Free surface moisture: coarse aggregate = dry state and fine aggregate = dry state

Test of sieve analysis: use the IS code 383 2016

For coarse aggregate: Use table7 for coarse aggregate

IS sieve sizes mm	Coarse aggregate		Percentage of different fractions			Remark
	Analysis of coarse aggregate fraction					conforming to IS 383 code
	I	II	I	II	III
20	100	100	60%	40%	100%
10	0	71.20	0	28.3	28.5
4.75		9.40		3.7	3.7
2.36		0

for fine aggregate: Grading zone II of table 9 of 383-2016 for fine aggregate

3. Target mean strength

ft= target average compressive strength at 28 days.

fck = Characteristic strength of concrete at 28 days in N/mm^2

S = standard deviation = 5, from (table 1 IS 10262-2009)

So, N/mm^2

4. Selection of water cement ratio:

From table 5 of IS 456-2000 for severe exposure conditions maximum water-cement ratio = 0.45

5. Selection of water content:

Given in the (IS 10262-2009), for the desired workability (other than 25 to 50 mm slump range), the required water content may be established by trial or an increase by about 3 percent for every additional 25 mm slump or alternatively by use of chemical admixtures conforming to IS 9103.

so, The estimated value of water content for 75mm slump = 186+(3/100) x186 = 191 lit.

As per superplasticizer is used the water content can be reduced by up to 20%

Based on trials water content reduction of 20% is achieved with a plasticizer. Hence, the arrived water content = 191x0.80 = 152.8 lit.

6. Selection of cement content with fly ash:

Water cement ratio =0.45

Cementitious material (cement + fly ash) = (water content) / 0.45

= 152.8/0.45

=340.45 kg/mm^3

according to the very exposure condition “severe” the minimum cement content =320 kg/mm^3 so, it’s safe. 320 340.45 kg/mm^3, hence ok.

Estimated cement content = 340.45 kg/mm^3 (taken).

To proposition a, mix containing fly ash the following steps should be taken-

(a)the percentage of fly ash needs to be decided based on project requirements and the quality of the material.

(b) In some cases, increases in Cementous material can be warranted. An increase in Cementous material content and its percentage may be based on experience and trial

increase by 10% Cementous material content in the calculation of cement content.

Cementous material content = 340.45 x 1.10 = 374.50 kg/mm^3

Water content = 152.8 kg/mm^3

Therefore, water cement ratio = 152.8/374.50 = 0.40

Assumed water cement ratio = 0.40

flyash@30% of total Cementous material content = 374.50 x (30/100) = 112.35 kg/mm^3

cement OPC grade 43 = 374.50 – 112.35 = 262.15 kg/mm^3

saving material of cement while using ash = 340.45 – 262.15 = 42.3 kg/mm^3

fly ash content being utilize = 112.35 kg/mm^3

7. Proportion of volume of coarse aggregate and fine aggregate content:

From table 3 IS 10262-2009 volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate Zone 1 for water content ratio of 0.5 = 0.6

In this study, the water-cement ratio = 0.40

Therefore, the volume of coarse aggregate needs to be increased to decrease the fine aggregate. As the water-cement ratio is lower by 0.10 the proportion of the volume of coarse aggregate is increased by 0.02 (at the rate of -/+0.01 for every 0.05 change in water-cement ratio)

Therefore, the corrected volume of coarse aggregate for water cement ratio of 0.40 = 0.62

Therefore, the pumpable concrete these values are reduced by 10%

Volume of coarse aggregate = 0.62*0.9 = 0.558

Volume of fine aggregate content = 1- 0.558 = 0.442

8. Mix Calculations:

The mix calculation per unit volume of concrete shall be as follow

• Volume of concrete = 1m^3
• Volume of cement = (mass of cement / specific gravity) *1/1000

= 262.15/3.15*1/1000

= 0.0833 m^3

(c) Volume of mass fly ash = (mass fly ash / specific gravity) *1/1000

= (112.35/2.2) * (1/1000) = 0.0510 m^3

(d)Volume of water content = (mass water / specific gravity) *1/1000

= (1/152.8) *(1/1000)

=0.1528 m^3

(e) Volume of chemical admixture = (mass of chemical admixture / specific gravity) *1/1000

= (6.807/1.145) *1/1000 = 0.006804 m^3

(f) Volume of FA and CA = [a(b+c+d+e)]

= [1-(0.0833 + 0.0510 +0 .1528 + 0.006804] = 0.706 m^3

Mass of coarse aggregate = e * volume of coarse aggregate x specific gravity of fine aggregate *1000 = 0.706 x 0.558 x 2.74 x 1000 = 1080.42 kg/m^3

Mass of fine aggregate = e * volume of fine aggregate x specific gravity of fine aggregate *1000 = 0.706 x 0.442 x 2.74 x 1000 = 855.022 kg/m^3

9. Mix proportion for the trial number

Cement = 262.15 kg/mm^3

Water = 152.8kg/mm^3

Fly ash = 112.35 kg/m^3

Fine aggregate = 855.022 kg/m^3

Coarse aggregate = 1080.42 kg/m^3

Chemical admixture = 6.802 kg/m^3

w/c ratio = 0.4

10. Obtained Result of Mix Proportion

Mix Ratio = 1: 3: 4

-------------------------------------------------------------------------------------------------------------------------

Objective 2 Calculate the Concrete Mix Design for M50 grade concrete without fly ash

General: Design mix concrete is a process of selecting ingredients for a concrete mixture and deciding on their proportions. The step-by-step process of the mixed grade of concrete has been explained below with using the various Indian Standard codes.

1. Stipulating for Proportioning:

Garde of concrete = M50

Grade or type of cement = OPC 53 grade conforming to IS 8112

Type of mineral admixture: fly ash conforming to IS 3812(PART1)

Maximum nominal size of aggregate = 20mm

Exposure condition: very severe (for RCC)

Minimum cement content = 340 kg/m^3 (table 5 from IS 456-2000 code – Exposure condition = very severe)

Maximum water cement content = 0.45 (table 5 from IS 456-2000 code – Exposure condition = very severe)

Workability =100mm

Method of placing concrete = for pumpable concrete

Type of aggregate: crushed angular aggregate

Maximum cement content: 450 Kg/m^3

Degree of supervision = good

Type of aggregate: crushed angular aggregate

Chemical admixture = superplasticizer

2. Test Data required for materials: Test data required for the material obtained from the manufacturer

Grade or type of cement = OPC 53 grade form code IS 8112

Specific gravity

Cement =3.15

Coarse aggregate = 2.65

Fine aggregate = 2.61

Chemical admixture = plasticizer code IS 9103

Surface moisture = coarse aggregate = 0, fine aggregate =0

3. Mix Calculation:

(1) Target mean strength N/mm^2

ft= target average compressive strength at 28 days.

fck = Characteristic strength of concrete at 28 day in N/mm^2

S = standard deviation = 5, from (table 1 IS 10262-2009)

(2) Selection of water cement method ratio

As per IS code 10262-1982 ------------ eq(i)

Fig.1 w/c = the value does not act on the curve it's beyond the curve

Fig.2 w/c = 0.32

As per IS code 456-2000 ----------- eq(ii)

Assumed very severe exposure condition from Table 5

w/c = 0.45 (maximum range) we use lower than this value, i.e., w/c = 0.4

As per IS code 10262-2019 ----------- eq(iii)

from the [curve 1] w/c = 0.38

Refer to the latest procedure for selecting the w/c so, that we choose the w/c value from the eq(ii) and eq(iii), compare the value, and take the minimum value. i.e., w/c = 0.38

(4) Calculation of water content:

IS per 10262-2009 from Table 2

Water content for 20mm size aggregate = 186 kg/m^3

In clause 4.1, For 100mm slump water content = 186+(6/100*186) = 197 lit.

Use superplasticizer is used to reduce 25% water content.

New water content =197*0.75 =147.75 kg/m^3

(5) Calculation of cement content:

water content as per concrete = 147.75 kg/m^3

w/c ratio = 0.38

cement content = 147.75/0.38 = 388.82 kg/m^3

according to very severe conditions the minimum cement content = is 388.82 kg^3 so, it’s safe.

388.82 kg/m^3, hence ok.

cement content = 388.82 kg/m^3, (taken)

assumed weight of admixture = 2% weight of cement

= (2/100) x (388.82) = 7.776 kg/m^3

(6) Calculation of Fine aggregate and coarse aggregate:

As per IS code 10262-2009, table 3, for zone2

Volume of coarse aggregate for zone 2 = 0.62

w/c 5= 0.62

for w/c 0.38 =

X= [(0.5-0.38) x 0.01/0.05)]

= (0.12) x (0.2) = 0.024

X= 0.024

Volume of coarse aggregate = 0.62+0.024 = 0.682

For pumpable concrete, the Volume of coarse aggregate reduced by 10%

New volume of coarse aggregate =0.682*0.9 = 0.6138

Volume of fine aggregate = 1 – 0.6138 = 0.3862

(7) Mix calculations:

(a) Volume of concrete = 1 m^3

(b) Volume of cement = (mass of cement/specific gravity of cement) x (1/1000)

= 388.82/3.15 = 0.123 m^3

(c ) Volume of water = (mass of water/specific gravity of water) x (1/1000)

147.75 /1000 = 0.147 m^3

(d) Volume of chemical admixture = (mass of admixture /specific gravity of admixture) x (1/1000)

(7.776/1.145) x 1000 = 0.0068 m^3

(e) Volume of FA and CA = [a- (b+c+d+e)] = [1-(0.123 + 0.147 + 0.0068] = 0.7232 m^3

(f) Mass of coarse aggregate = Volume of all aggregate x volume of coarse aggregate x specific gravity of coarse aggregate x 1000

Mass of coarse aggregate = 0.7232 x 0.6138 x 2.65 x 1000 = 1176.65 kg/m^3

Mass of fine aggregate = Volume of all aggregate x volume of fine aggregate x specific gravity of fine aggregate x 1000

Mass of fine aggregate = 0.7264 x 0.3862 x 2.61 x 1000 = 732.28 kg/m^3

(8) Mix Proportion of concrete:

Cement = 388.82 kg/m^3

Water = 147.15kg/m^3

Fine aggregate = 732.28 kg/m^3

Coarse aggregate = 1176.65 kg/m^3

Chemical admixture = 7.776 kg/m^3

w/c ratio = 0.38

(9) Obtained Result of Mix Proportion:

Mix Ratio = 1: 2 :3

----------------------------------------------------------------------------------------------------------------------