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CHAPTER 4

MIX DESIGN OF CONCRETE WITH

MANUFACTURED SAND

4.1 GENERAL

The design of concrete mix requires complete knowledge of the

various properties of the ingredients used in concrete. This chapter discusses

the properties of materials used and the mix proportioning of M 20, M 30 and

M 40 grades of concrete with the replacement levels of manufactured sand

from 0 to 100%. Besides it considers the specific gravity and fineness

modulus values of each replacement level of manufactured sand.

4.2 MATERIALS

4.2.1 Cement

Portland pozzolana cement conforming to IS 1489 – 1991 was used

for this experimental investigation. The physical and chemical properties of

cement are shown in Tables A 1.1 and A 1.2.

4.2.2 Coarse Aggregate

Locally available crushed aggregate of 20mm down size

conforming to graded aggregate as per IS: 383 – 1970 was chosen for the

present investigation. The coarse aggregate was tested as per the procedure

given in IS: 2386 - 1963 and the results are given in Table A 1.3.

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4.2.3 Fine Aggregate

Locally available river sand was used as fine aggregate. The natural

river sand was replaced by the manufactured sand. Here the manufactured

sand varied from 0 to 100% as ten increments and designated as A, B, C, D,

E, F, G, H, I, J and K respectively. The physical and chemical properties of

the fine aggregate are given in Tables A 1.4 and A 1.5. The particle size

distribution curve of the fine aggregate is shown in Figure 4.1.

Figure 4. 1 Particle size distribution analysis of MS

Figure 4.1 shows the grading curves of natural sand and the various

proportions of manufactured sand. In the figure, L.L represents the lower limit

and the U.L represents the upper limit of the particle size distribution curves

of sand. From the figure, it is noticed that the particles of size less than 300

microns are higher for the proportions of 80 %, 90 % and 100 %manufactured

sand.

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4.2.4 Water

Water is a key ingredient in the manufacture of concrete. A potable

tap water was used in this research.

4.3 MIX DESIGN (IS 10262 – 1982)

Mix design is a process that consists of two interrelated steps.

It involves

1) Selection of suitable ingredients (cement, aggregate, water and

admixtures) of concrete.

2) Determining their relative quantities (‘proportioning’) to

produce as economically as possible, concrete of the

appropriate workability, strength and durability.

In this thesis, mix proportions for M 20, M 30 and M 40 grade

concrete were arrived at for the different replacement levels of natural sand

with manufactured sand as ten increments. This meant considering the

specific gravity and fineness modulus values of each replacement level of

manufactured sand. In the process, the mixes were named as A, B, C, D, E, F,

G, H, I, J and K for 0 to 100% respectively. Concrete mixes were designed as

per IS 10262 – 1982. Mix proportions of M 20, M 30 and M 40 grade

concrete are given in Tables 4.1 to 4.3 and Figures 4.2 to 4.4.

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Table 4.1 Ingredients of M 20 grade concrete

D Cement(kg)

F.A(kg)

C.A(kg)

Water(Lit)

A/Cratio F.A:C.A

F.A:C.A(based onsurface

index value)A 372 550.56 1242.48 197.16 4.82 30 : 70 1 : 2.26B 372 550.56 1253.64 197.16 4.85 30 : 70 1 : 2.28C 372 550.56 1223.88 197.16 4.77 31 : 69 1 : 2.23D 372 587.76 1197.84 193.44 4.80 33 : 67 1 : 2.04E 372 587.76 1197.84 189.72 4.80 33 : 67 1 : 2.04F 372 591.48 1197.84 189.72 4.81 33 : 67 1 : 2.03G 372 617.52 1197.84 186.00 4.88 34 : 66 1 : 1.94H 372 617.52 1197.84 186.00 4.88 34 : 66 1 : 1.94I 372 613.80 1197.84 182.28 4.87 34 : 66 1 : 1.95J 372 602.64 1197.84 182.28 4.84 33 : 67 1 : 1.99

K 372 595.20 1223.88 182.28 4.88 33 : 67 1 : 2.00

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Figure 4.2 Percentages of ingredients for M 20 grade concrete

Table 4.2 Ingredients of M 30 grade concrete

D Cement(kg)

F.A(kg)

C.A(kg)

Water(Lit)

A/Cratio F.A:C.A

F.A:C.A(based onsurface

index value)A 404.35 529.38 1247.81 197.39 4.40 30 : 70 1 : 2.36B 404.35 526.66 1247.80 196.03 4.39 30 : 70 1 : 2.37C 404.35 539.17 1220.88 193.13 4.35 31 : 69 1 : 2.26D 404.35 565.67 1193.76 191.72 4.35 32 : 68 1 : 2.11E 404.35 566.57 1193.77 191.23 4.35 32 : 68 1 : 2.11F 404.35 570.31 1193.78 189.74 4.36 32 : 68 1 : 2.09G 404.35 595.13 1193.78 187.34 4.42 33 : 67 1 : 2.01H 404.35 593.22 1193.76 186.51 4.42 33 : 67 1 : 2.01I 404.35 594.11 1193.78 183.87 4.42 33 : 67 1 : 2.01J 404.35 592.74 1193.78 181.80 4.38 33 : 67 1 : 2.06K 404.35 578.90 1193.78 178.52 4.42 33 : 67 1 : 2.01

Figure 4.3 Percentages of ingredients for M 30 grade concrete

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Table 4.3 Ingredients of M 40 grade concrete

D Cement(kg)

F.A(kg)

C.A(kg)

Water(Lit)

A/Cratio F.A:C.A

F.A:C.A(based onsurface

index value)A 486.5 399.69 1328.91 192.18 3.55 23 : 77 1 : 3.32B 486.5 397.63 1328.90 191.15 3.55 23 : 77 1 : 3.34C 486.5 397.63 1328.90 191.15 3.53 24 : 76 1 : 3.16D 486.5 437.92 1276.53 187.99 3.52 26 : 74 1 : 2.91E 486.5 438.61 1276.53 187.22 3.53 26 : 74 1 : 2.91F 486.5 441.49 1276.51 186.15 3.53 26 : 74 1 : 2.89G 486.5 460.72 1276.29 184.31 3.57 26 : 74 1 : 2.78H 486.5 459.63 1276.29 183.64 3.57 26 : 74 1 : 2.78I 486.5 459.92 1276.29 181.61 3.57 26 : 74 1 : 2.78J 486.5 458.86 1276.29 181.22 3.54 26 : 74 1 : 2.78K 486.5 448.16 1276.28 177.46 3.57 26 : 74 1 : 2.78

Figure 4.4 Percentages of ingredients of M 40 grade concrete

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4.4 DISCUSSION OF TEST RESULTS

4.4.1 Properties of Materials

From Figure 4.1, it is found that the particle sizes of manufactured

sand for the proportions A to H lie within the lower and upper limits. But the

proportions I, J and K (80, 90 and 100% manufactured sand) exceed the upper

limit. This represents that the finer fractions below 300 microns are higher in

these proportions, which may affect the workability and the strength of the

concrete.

4.4.2 Mix Design

From Tables 4.1 to 4.3 and Figures 4.2 to 4.4, it is observed that for

the constant cement content, the fine aggregate content is increased while

increasing the proportions of manufactured sand due to the coarser particles

of manufactured sand. It is also noticed that the water content is slightly

reduced with the increase in proportions of manufactured sand due to the high

surface moisture content of manufactured sand, which may increase the

strength of the concrete.

4.5 CONCLUDING REMARKS

According to the findings of this research, the gradation of the

manufactured sand, the increased amount of aggregate/cement ratio and the

reduced amount of water cement ratio, the workability of the concrete may get

reduced and the strength of the concrete may be increased. The presence of

large amount of fines in 80, 90 and 100% manufactured sand may reduce the

strength of the concrete in these proportions.