Tag Archives: mortar

What is grade 53 of cement? 

What is the 53 grade in cement? Read this post which explains the basic concepts behind the grade :

https://www.quora.com/What-is-the-53-grade-in-cement/answer/Santosh-Kulkarni-37?share=ad0d3801&srid=zM5g

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M sand economical than Natural sand ?

Dear Friends ,

Every year during the rainy season , the natural or river sand becomes short supply. Construction work suffers. There are other options available for the river sand…such as Crushed sand or M sand.

This post explores whether using the M sand as a replacement to the natural sand is econoimcal ?

Read it to know

Is a manufactured fine aggregate pricier than sand? by Santosh Kulkarni https://www.quora.com/Is-a-manufactured-fine-aggregate-pricier-than-sand/answer/Santosh-Kulkarni-37?share=bb5ce272&srid=zM5g

MORTAR FOR PLASTER ?

Dear All ,

I am so happy to see all of you here .

So nice of you to be following this blog.

I get further inspired when I know that you are going to immediately read this post.

Thank you so much for the fantastic support.

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Why not watch Masonry on video ?

Here is the link : Masonry

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All in the family of concrete

Overview:

This article explains the various types of materials required in mortar , concrete and reinforced cement concrete.

Before we go forward let us understand the basics:

Hydration of cement :

Cement reacts in the presence of Water and  a process known as hydration takes place . Heat is evolved during this process and hence it is known as exothermic .

Cement mortar:

When sand is added to the cement & water , it makes a substance which is known as cement mortar.

Cement mortar is used in joining , pointing and plastering .It can be made in various proportions of cement : sand such as :
1:1, 1:2 , 1:3 ,1:4 ,1:5 ,1:6.

The ratios 1:1, 1:2 are used for punning , the ratios 1:3 ,1:4 are used for plastering whereas the ratios 1:5 ,1:6 are used for joining of brick masonry and stone masonry.

SAND JUST RECEIVED AT SITE. TRUCK DIMENSIONS : 15 ' X 8 ' X 3' 6". VOLUME OF SAND :             420 CUBIC FOOT                   OR  4.2 BRASS
SAND JUST RECEIVED AT SITE. TRUCK DIMENSIONS : 15 ‘ X 8 ‘ X 3’ 6″.
VOLUME OF SAND : 420 CUBIC FOOT OR 4.2 BRASS

Cement concrete:

When aggregate is added in this mortar , it makes a substance known as cement concrete.

In order to make a dense concrete , it is necessary to properly select the particle sizes of fine aggregate ( sand ) and coarse aggregates and this process is known as blending .

Concrete is shown on drawing as              CC ( cement concrete ) or PCC ( Plain cement concrete ) and is used in :

Levelling course below footings
Bed concrete below flooring
Benching below underground pipes
Plinth protection
Coping on the top of parapet wall

Cement concrete is quite strong in compression but is rather weak in tension. Steel bars are excellent in tensile strength.
So , Steel bars are added in cement concrete to make it strong in tension .

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Reinforced Cement concrete:

The mechanism of Cement concrete and steel bars together is called reinforced cement concrete.
This has the compressive strength of concrete and also is blessed with the tensile strength due to presence of steel bars in the tension zone.
The working of steel bars in the concrete works on the basis of bond developed between the surface of concrete and steel bars .

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HYSD bars :
This bond is further improved by the  undulating or rough surface of the steel bars which is possible in tor-steel or ribbed bars.

Now in this context , let us make a list of what all is needed to make mortar , concrete and RCC .

A CEMENT BAG WEIGHS 50 KG AND HAS A VOLUME OF 35 LITRES.
A CEMENT BAG WEIGHS 50 KG AND HAS A VOLUME OF 35 LITRES.

Cement:

Can be Ordinary Portland Cement  or Pozzolona Portland Cement :
OPC is available in grades 43 & 53.
Whereas PPC is available in grade 33 only.

Meaning of grade of cement :
When it is said that the cement is 43 grade , it means that if a cube is made in a cement mortar using this cement and tested , the average crushing strength on 28th day shall not be less than                 430 Kg/Sq.cm.

The standard cube size is
7.07 cm x 7.07 cm x 7.07 cm.

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Sand:
It can be River sand or Crushed sand.
Both of them can be used in concrete in varying proportions.

The particle size has to be between 
75 microns to 4.75 mm .

One problem with river sand is its silt content and it should be controlled within 3% . In case , the silt content is more than 3% then the sand must be washed prior to it’s use.

If the particle sizes larger than 4.75 mm are present in larger proportions , then it is 
advisable to screen the sand prior to use in mortar.

Water:
For optimum results , the water should be free from chemicals and impurities and hence it is better to use the potable water for concrete.

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Aggregate:

The aggregate is designated by the mean size of aggregate ( MSA ) and the suggested size for RCC is 10 to 20 mm.

Admixtures:

These are of three groups:
Plasticizers , Retarders &
Water proofing chemicals.

Plasticizers help in improving workability of concrete without addition of extra water during mixing.
Retarders decelerate the setting time of concrete and thus transportation of ready mix concrete becomes feasible over long distances.
Waterproofing chemicals are used to make the concrete impermeable to passage of water.
These are used during the concreting of the terrace slab or sunk portions below toilets or balconies or wet areas of a building.

Steel bars:

Can be either Mild steel bars or HYSD bars.
Mild steel bars are available in grade Fe250.
High yield strength deformed bars
( HYSD ) are available in grades of Fe 415 , Fe 500 and Fe 550.

Meaning of grade :

Grade Fe415 means it has an ultimate tensile strength of 4150 Kg/Sq.cm.

Binding wire:
Used for binding the steel bars together . Main bars to distribution ,
Main bars to stirrups ,
Lapping of bars.

Mild steel wire 
GI wire
Suggested diameter is 1.6 mm.
Cover blocks:
Mortar blocks
PVC blocks
15 mm
25 mm
40 mm
50 mm

Why so many bricks ???

Dear Reader ,

In my experience , the subject of estimation is quite boring to the students as well as field people.

In that context , we are going through a series of articles devoted to the arithmetic involved in construction.

We have already discussed the estimation of materials in concrete

( Read post : Vow..what a concrete )

Now we shall travel in the masonry today.

Just keep your patience when you read.

If you get bored , just Stop and take a break.

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Take a scrap pad and a calculator and do some jugglery yourselves.

That’s how you shall keep aligned .

Re-continue and reflect as many times as you feel.

There is no hurry.

Happy Calculating !

Overview:

We talked about the general aspects of the masonry in the previous post.
We also spoke about  the stone masonry

( Read : Throw the stone..carefully )

Now we shall learn the arithmetic issues involved in counting the bricks.

We shall  be able to find out the :
Number of bricks needed for the masonry work and also the mortar needed for the job.
In other words ,for a given masonry wall we shall be able to compute:

1.No of bricks 

2.No of cement bags
3.Sand

And then we can also find out the total material cost.

This shall help us in:
1.Budgeting for materials
2.Ordering the material

Ok ? so all geared up ?
let us begin..here we go:

The Data:
The brick wall which we need to build is 5 m long, 4 m high and it is 200 mm thick.
It is to be jointed in Cement mortar 1:6.
The bricks of size 200 mm x100 mm x 70 mm have been approved.

CHECK THE ACTUAL DIMENSIONS OF THE BRICKS ON SITE
CHECK THE ACTUAL DIMENSIONS OF THE BRICKS ON SITE

The method:
1.Calculate the volume of one brick :
0.2m x 0.10m x 0.07m = 0.0014 CuM.
2.Find number of bricks per CuM:
= 1/0.0014 = 714 nos.

So 714 bricks shall be needed if there is no mortar joint. Right ?

3. Now,assume that there is a mortar joint of 10 mm thickness between the  bricks.

So, increase each dimension of brick by 10 mm.

Thus,the volume of each brick with mortar shall be :
0.21 x 0.110 x 0.08 =0.001848 CuM.

4..Again, Find number of bricks per CuM:

= 1/0.0011848  = 541 nos.

NORMALLY CEMENT MORTAR CM ( 1:6 ) IS USED FOR THE BRICK WORK
NORMALLY CEMENT MORTAR CM ( 1:6 ) IS USED FOR THE BRICK WORK

5.Thus, number of bricks have reduced from 714 to 541 due to the presence of mortar.

6.Therefore, 714 – 541 = 173 Bricks represent the volume of cement mortar.

173 x 0.0014= 0.2422 CuM.
7.Summary I:

We shall need 541 bricks and 0.24 CuM of cement mortar for 1 CuM of brick work.

TRAY FOR MIXING CEMENT MORTAR at the location of brickwork
TRAY FOR MIXING CEMENT MORTAR at the location of brickwork

8.Now we also need to find out how many cement bags and how much quantity of sand is needed 

for 0.24 CuM of mortar .

Let us assume that the mortar quantity is CuM.

The mix is CM 1:6.
We shall use dry mix method.

Cement: [1.52/(1+6)]x 28.8 =  [0.2171]x 28.8 = 6.25 Bags

Sand: [0.2171] x 6  = 1.302  CuM.

Consumption of materials for 1 CuM of cement mortar (1:6):

Cement: 6.25 Bags
Sand:   1.302 CuM.

A CEMENT BAG WEIGHS 50 KG AND HAS A VOLUME OF 35 LITRES.
A CEMENT BAG WEIGHS 50 KG AND HAS A VOLUME OF 35 LITRES.
Now ,we actually need only 0.24 CuM of mortar for 1 CuM of brick work

Hence for 0.24 CuM of mortar , we shall need :
Cement: 6.25 Bags x 0.24 =1.5 bags
Sand:   1.302 CuM. x 0.24= 0.3125 CuM.

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9.Summary II:
Consumption of materials for 1 CuM of Brickwork :
Cement: 1.5 bags
Sand:     0.3125 CuM.
Bricks: 541 Bricks

10.Now we are at the final lap:
Volume of brick wall:
5 x 4x 0.2 = 4 CuM

Therefore material consumption shall be:

Cement: 1.5 bags x 4 =  bags
Sand:     0.3125 CuM. x 4 = 1.25 CuM.
Bricks: 541 Bricks x 4 = 2164 Bricks

If the unit rates are known we can also find out total cost of the materials.

RCC FRAMED STRUCTURE. [ Brickwork in full swing ]
RCC FRAMED STRUCTURE.
[ Brickwork in full swing ]
11.Assume that :

Bricks : INR 4200 per 1000. [ INR 4.2  per no ]

Sand : INR 4500 per Brass or 100 Cft.

[ INR 45 per cft or 45 x 35.29 = INR 1588 per cuM.]

Cement : INR 300 per bag of 50 Kg.

The material cost shall be as follows :

Cement:  bags@ 300 =       1800
Sand:     1.25 CuM.@ 1588 = 1985
Bricks:  2164 Bricks@ 4.2 =  9088

Total cost :1800 + 1985 + 9088

= INR 12,873 

12. Now we can find out the materials cost per CuM  of  brick work :

12,873 /4 = INR 3218.25 per CuM of brick work 

or 3218.25/35.29 = INR 91.19 per Cubic feet of brick work

BRICKS STORED AT THE SITE
BRICKS STORED AT THE SITE

Author’s note :

Dear Reader ,

Hope you have understood the basics.

1.Remember , you don’t have to do all this calculation every .

Just memorize the unit cost i.e INR 3218.25 per CuM or INR 91.19 per Cubic feet of brick work .

As long as the material rates are the same, the cost shall be the same.

2. For those comfortable with spread sheets , once do this calculation in the spread sheet with proper formulae. Later , when any of the variable changes ,the moment you revise that figure, the entire computations shall be automatically revised.

SAK.PORTRAIT.27.8.2012

Its really a fun.

believe me.

Happy journey on the path of estimations.

Throw the stone…carefully.

Overview:

In our detailing of a building we have already discussed the RCC elements in a building.

From previous post we are reviewing the masonry work.( Read: Laying bricks for building success)
This article takes the reader to the next level :Understanding Stone masonry.

LOOK AT THE OLD STONE ARCH BRIDGE
LOOK AT THE OLD STONE ARCH BRIDGE

The Stone Masonry:

Everyone likes the aesthetics and the grace of the stone walls. The sturdy facade which a stone wall creates is incomparable to any other form .Stone masonry uses the natural stones and hence may be we move forward towards the direction of the nature or may be, the stone wall reminds us of our forgotten past when we used to live inside the stone caves.

LOOK AT ANOTHER  BEAUTIFUL  STONE ARCH AND STONE MASONRY          [ CR ]USED IN A RELIGIOUS BUILDING
LOOK AT ANOTHER BEAUTIFUL STONE ARCH AND STONE MASONRY [ CR ]USED IN A RELIGIOUS BUILDING

Different styles:
There are 4 distinct methods in stone masonry depending on whether the stone [ which is also called  as Rubble]  has been dressed ( shaped) or is used as it is ( no shape given after breaking in quarry)

A.With dressed stones:
1.Ashlar masonry
2.Coursed Rubble masonry( CR)

Ashlar is more refined as compared to coursed rubble masonry. Ashlar has greater dimensional control and is more appealing from aesthetics point of view.
Both are normally used for monumental works or public buildings.

Why ashlar or coursed rubble masonry are not suitable for modern buildings ?

1.Skilled masons to dress the stone are not available.
2.Productivity is quite less.
3.Dead weight of walls is much higher

In short when cost constraints are not there , adequate time is available and most important, magnificent looks are important directly  go for Ashlar or UCR masonry.

B.With Undressed stones:

3. Un-Coursed Rubble masonry ( UCR)
4.Random rubble masonry ( RRM)

Both of these use the stone as it is. The stone are quarried and further broken in medium size from 9″ to 12″ . the joining is done in cement mortar CM ( 1:6 ).
A cross stone called as Header is provided across the wall to give a binding on the wall width .
Some times RCC precast headers can also be given. There is also a practice of keeping reinforcement bars across the width .

There is not much difference between UCR and RRM  . However, note the following:
1.UCR is better in overall appearance than RRM and hence as a convention it is used for walls above the plinth .
2.RRM is used for wall foundations or retaining walls since the looks are not important.

UN-COURSED RUBBLE MASONRY IN THE COMPOUND WALL.
UN-COURSED RUBBLE MASONRY IN THE COMPOUND WALL.
RANDOM RUBBLE MASONRY USED IN THE COMPOUND WALL . [ REAR PORTION ]
RANDOM RUBBLE MASONRY USED IN THE COMPOUND WALL .
[ REAR PORTION ]