Awarded as the best online publication by CIDC

Mix Design

How To Make Concrete At Site? M 25 Example

By
Er. Kaushal Kishore ,
Materials Engineer, Roorkee

PORTLAND CEMENT:
Joseph Aspdin, a mason at Leeds prepared a cement in 1824 by heating a mixture of finely-divided clay and hard limestone in a furnace until CO2 had been driven off; this temperature was much lower than that necessary for clinkering. The prototype of modern cement was made in 1845 by Isaac Johnson, who burnt a mixture of clay and chalk until clinkering, so that the reaction necessary for the formation of strongly cementitious compound took place. The name ‘Portland Cement’ was given due to the resemblance of the colour and quality of the hardened cement to Portland stone- a limestone quarried in Doset.

The process of manufacturing of cement consists essentially of grinding the raw materials ( calcareous materials such as limestone or chalk and argillaceous materials such as shale or clay), mixing them intimately in certain proportion and burning in a large rotary kiln at a temperature of upto about 14500C when the material sinters and partially fuses into balls known as clinker. The clinker is cooled and ground to a fine powder, with some gypsum added, and the resulting product is the commercial Portland Cement so widely used throughout the world.

MAKING CONCRETE:
Just mix cement, aggregates and water, cast this mix in a mould, open the mould next day. A uniform hard mass will be found, which is known as concrete, any body can make it. The simplecity in making concrete make this material to be look like very simple in its production, yet it as not so simple. Due to ignorance about concrete no other building materials ever mis-used as concrete in the construction. In India concrete is being used in the construction since the last 70 years. Yet 80% of the builders have no proper understanding of this materials. Go to any construction site (except big construction sites) you will find that sand and aggregates are being taken in iron tasla or cane baskets to charge the mixer without the consideration of site aggregates actual grindings, moisture content and bulking of sand. The water is poured in the mixer without any measured quantity. It could be well imagine what sort of concrete structure will be made with the concrete being produced in this crude method.

Most of the contractors, builders, masons etc. still follow 1:2:4 or 1:1.5:3 mixes they are not aware of Design Mixes and Concrete Admixtures. This paper described how Design Mixes can be converted into volume with 1 Bag Cement, 2 Boxes of sand and 4 Boxes of Aggregate. The site practical problem is the dispersion of water and liquid admixtures into the mixer. For this the site should fabricate a plastic circular graduated measuring container of 30 lit capacity with a tap fitted at its bottom. This container is to be fitted on top of the mixer. From this container water and liquid admixtures can conveniently poured direct into the mixer in a measured quantity.
(more…)

M-35 Mix Designs as per IS-10262-2009

By
Raj Mohammad Khan

Following table shows the M-35 Mix Designs as per IS-10262-2009, hope this helps all civil engineers here
(more…)

M-30 Mix Designs as per IS-10262-2009

By
Raj Mohammad Khan

Following table shows the M-30 Mix Designs as per IS-10262-2009, hope this helps all civil engineers here

(more…)

M-25 Mix Designs as per IS-10262-2009

By
Raj Mohammad Khan

Following table shows the M-25Mix Designs as per IS-10262-2009, hope this helps all civil engineers here
(more…)

M-20 Mix Designs as per IS-10262-2009

By
Raj Mohammad Khan

Following table shows the M-20 Mix Designs as per IS-10262-2009, hope this helps all civil engineers here

M-20 CONCRETE MIX DESIGN

As per IS 10262-2009 & MORT&H

A-1

Stipulations for Proportioning

1

Grade Designation M20

2

Type of Cement OPC 53 grade confirming to IS-12269-1987

3

Maximum Nominal Aggregate Size 20 mm

4

Minimum Cement Content (MORT&H 1700-3 A) 250 kg/m3

5

Maximum Water Cement Ratio (MORT&H 1700-3 A) 0.5

6

Workability (MORT&H 1700-4) 25 mm (Slump)

7

Exposure Condition Normal

8

Degree of Supervision Good

9

Type of Aggregate Crushed Angular Aggregate

10

Maximum Cement Content (MORT&H Cl. 1703.2) 540 kg/m3

11

Chemical Admixture Type Superplasticiser Confirming to IS-9103

A-2

Test Data for Materials

1

Cement Used Coromandal King OPC 53 grade

2

Sp. Gravity of Cement 3.15

3

Sp. Gravity of Water 1.00

4

Chemical Admixture Not Used

5

Sp. Gravity of 20 mm Aggregate 2.884

6

Sp. Gravity of 10 mm Aggregate 2.878

7

Sp. Gravity of Sand 2.605

8

Water Absorption of 20 mm Aggregate 0.97%

9

Water Absorption of 10 mm Aggregate 0.83%

10

Water Absorption of Sand 1.23%

11

Free (Surface) Moisture of 20 mm Aggregate nil

12

Free (Surface) Moisture of 10 mm Aggregate nil

13

Free (Surface) Moisture of Sand nil

14

Sieve Analysis of Individual Coarse Aggregates Separate Analysis Done

15

Sieve Analysis of Combined Coarse Aggregates Separate Analysis Done

15

Sp. Gravity of Combined Coarse Aggregates 2.882

16

Sieve Analysis of Fine Aggregates Separate Analysis Done

A-3

Target Strength for Mix Proportioning

1

Target Mean Strength (MORT&H 1700-5) 30N/mm2

2

Characteristic Strength @ 28 days 20N/mm2

A-4

Selection of Water Cement Ratio

1

Maximum Water Cement Ratio (MORT&H 1700-3 A) 0.5

2

Adopted Water Cement Ratio 0.5

A-5

Selection of Water Content

1

Maximum Water content (10262-table-2) 186 Lit.

2

Estimated Water content for 25 mm Slump 145 Lit.

3

Superplasticiser used nil

A-6

Calculation of Cement Content

1

Water Cement Ratio 0.5

2

Cement Content (145/0.5) 290 kg/m3

Which is greater then 250 kg/m3

A-7

Proportion of Volume of Coarse Aggregate & Fine Aggregate Content

1

Vol. of C.A. as per table 3 of IS 10262 62.00%

2

Adopted Vol. of Coarse Aggregate 65.00%

Adopted Vol. of Fine Aggregate ( 1-0.65) 35.00%

A-8

Mix Calculations

1

Volume of Concrete in m3 1.00

2

Volume of Cement in m3 0.09

(Mass of Cement) / (Sp. Gravity of Cement)x1000

3

Volume of Water in m3 0.145

(Mass of Water) / (Sp. Gravity of Water)x1000

4

Volume of Admixture @ 0% in m3 nil

(Mass of Admixture)/(Sp. Gravity of Admixture)x1000

5

Volume of All in Aggregate in m3 0.763

Sr. no. 1 – (Sr. no. 2+3+4)

6

Volume of Coarse Aggregate in m3 0.496

Sr. no. 5 x 0.65

7

Volume of Fine Aggregate in m3 0.267

Sr. no. 5 x 0.35

A-9

Mix Proportions for One Cum of Concrete (SSD Condition)

1

Mass of Cement in kg/m3 290

2

Mass of Water in kg/m3 145

3

Mass of Fine Aggregate in kg/m3 696

4

Mass of Coarse Aggregate in kg/m3 1429

Mass of 20 mm in kg/m3 1029

Mass of 10 mm in kg/m3 400

5

Mass of Admixture in kg/m3 nil

6

Water Cement Ratio 0.5

Advertisements

We are thankful to Er. Raj M. Khan for sharing this information with us on engineeringcivil.com. We hope this would be of great significance to civil engineers.