Concrete Mix Design is the process of
selecting suitable ingredients of concrete and determining their relative proportions
to produce a concrete of certain minimum strength and durability as
economically as possible.

Concrete Mix designer required a great
knowledge so that if there any difficulty comes he handles this problem. He
must aware these essential steps which are the basics of concrete mix Design.

Here we will explain all steps step
by step according to ACI 211. You should read this to clear your every point about Concrete Mix Design . Concrete Mix Design ACI 211 (Note: This process we will explain from
beginning so any one who want to make concrete design first time so it can help
more .

1.
Selection
of Source

2.
Quality
tests of Material (Aggregate, Sand and
water)

3.
Determinations
of Slump

4.
Calculation
of concrete mix design and final take
batch weight

5.
Trial
of Concrete Mix Design

6.
Selection
of final suitable design

**1.**

**Selection of Source**

In this step Designer first see from where
he will take material for Concrete Mix Design. He will confirm about below
mentioned two points with his Project Manager or Owner of Company that from
where company will take material. There are two steps

A.
Buy
some near source for Concrete Mix Design.

B.
Take
Material from other Company Crusher

A. Buy some near source for Concrete Mix Design

In this case you
have to visit near companies which are working around your project to meet with
their Material Engineer. You ask above out that from where they are taking
material for concrete work. You have to conform about location of aggregate
Source and natural sand from so he will give you the location that where the
source is present. It will give you a great help otherwise it will take a great
time to search this.

Now you will visit this
place with Consultant and will take simple from this place and will do quality
tests for this source.

**2.**

**Quality tests of Material (Aggregate, Sand and water)**

After taking material from source you have
to make Quality tests some test you will perform inside lab and some from
independent lab. Independent lab is outside lab in the city where they have all
the apparatus especially for cement, steel if your company doesn’t have apparatus
you have to perform these from outside.

List of Quality test which will you perform
from inside and outside lab. The complete procedure of these tests is present
in link below of each test

**Inside your Company Lab**

1.
Sieve
analysis of course and fine aggregate

2.
Dry rodded
unit weight

3.
Los Angles
abrasion test

4.
Soundness
of Course and fine Aggregate

5.
Specific
Gravity of course and fine aggregate

6.
Thin
and elongated for course aggregate

7.
Combined
gradation of course aggregate

8.
Combined
gradation of fine aggregate

9.
Clay
lumps and friable particles

10.
Combined
Specific Gravity and Absorption

**Outside Independent Lab**

For these test you have to give material to
independent lab they will perform all these test. After 3 days they will give
result of these tests

1.
Chemical
Analysis of water

2.
Petrographic
examination of course aggregate

3.
Chemical
analysis of course aggregate

4.
Organic
impurities in fine aggregate

5.
Potential
alkali reactivity chemical test method on course aggregate

6.
Potential alkali reactivity chemical test
method on course aggregate

**3.**

**Determination of maximum size of aggregate**

You are making
design you first determine that which will be the maximum size of aggregate. The
maximum size of aggregate depends upon three factors

1.
1/5

^{th}of Narrowest dimension between sides of forums,
2.
1/3

^{rd}the depth of slab,
3.
3/4

^{th}of spacing between reinforced bars
So you calculate this by yourself and your project manager will
also help you in determining of maximum size of Aggregate.

**4.**

**Determination of Slump**

The third main
important point in concrete mix design is determination of slump.

So this is the required
list of slump according to your structure you will take the value of slump from
this table. Suppose you structure is Reinforced foundation wall and footing in
this case required slump is 75 mm. So when you will make trail in your lab in
this case you see one point

That how much is the distance between
from your concrete batching plant and bridge or building. If distance is of 30
minutes so when you will make trail in laboratory in concrete mixture you must
bring 75mm slump after 30 minutes. So in future when your concrete mixture will
go from batching plant to Bridge it will com 75mm.

Note.
Slump can be increased when chemical admixture used but provided here two cases

1.
Admixture
treated concrete has lower water cement ration. Because admixture reduce amount
of water so in this case we can’t use higher w/c ratio.

2.
Use
limited amount of admixture so that there is no segregation potential or
excessive bleeding. Normally how much dosage we will use is mentioned on
admixture.

**5.**

**Water/cement ratio**

During trial in
lab slump can be control by water to cement ratio. You start

Your trail from
w/c 0.35 w/c

If you are making trial in lab after 30 minutes slump is coming 50
mm in this case you have to increase water to cement ratio to 0.36 if in 0.36
again slump is coming 65mm. now you have to increase your w/c 0.37 upto 0.45 or
more. When you achieve slump 75mm then at this point you take simple of concrete
for compressive strength for 3, 7 and 28 days. So if after 28 days strength is coming
.

When you achieve slump 75mm then at this
point you take simple of concrete for
compressive strength for 3, 7 and 28 days. So if after 28 days strength is coming
100% Then you can submit your design for approval in consultant.

**6.**

**Calculation of Concrete mix Design**

For this step I will give a practical concrete mix design excel
sheet which we have made in our lab so that it will give to reader a great help
when he will make practical.

We will explain only one trail other trail you can do by yourself
easily.

So you calculate by yourself with calculator

These are five sheets of calculation which excel format you can take also from me or you can take from your company Material Engineer.

In this we calculate

1. w/c ratio .

2. Water which we will get by multiplying cement with w/c ratio

__Calculation Sheet No 1__In this we calculate

1. w/c ratio .

2. Water which we will get by multiplying cement with w/c ratio

__Calculation Sheet No 2__In this sheet we will so calculation of

1. Estimated Strength

2. Air Content Percentage

3. Dry Rodded unit Volume of Course Aggregate

4. And weight of course Aggregate

__Calculation Sheet No 3__In this sheet we will do calculation for to determine volume of

1. Cement

2. Water

3. Absolute Volume of Course Aggregate

4. Volume of Air

5. Volume of Admixture

6. Absolute Volume of Fine Aggregate

5. Weight of Fine Aggregate

1. Course Aggregate

2. Fine Aggregate

3. Water

Note ( We will adjust weight because in Aggregates has moisture and absorption so we will take value of this all after this we will get accurate weight of Course and Fine Aggregate and Water

4. At last we will get the Final weight from aur above calculation

Cement

Water

3/4 " Size

3/8 " Size

Fine Aggregate

Admixture

so now when we will get all these weight then we will do lab trail in our lab. we will put all these ingridents in Manual mixture in Laboratory and when we achive desired slump then we will take 9 Sample 3 Cylinders we will crush after 3 Days and 3 Cylinder after 7 Days and next 3 Cylinder we will crush after 28 Days. If 28 Days Strength comes to 100 % the we will submit our design for approval.

this Design we achived desired strength and slump so we submitted it for approvel. Final Compressive Strength of Concrete Result which we will achive atlast. According to this we will use this concrete for our project

__This was the design which we made after 3, 7 and 28 days compressive Strength resul is preset. In__

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