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

# Tag Archives: mortar

# 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.**

**Why not watch Masonry on video ?**

Here is the link : **Masonry**

# 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.

**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 .

**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 .

**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**** .**

**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****.**

**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.

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.**

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:**

( Read : Throw the stone..carefully )

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**

**total**

**material**

**cost**

**.**

**This**** ****shall**** ****help**** ****us**** ****in****:**

**1.****Budgeting**** ****for**** ****materials**

**2.****Ordering**** ****the**** ****material**

**The**** D****ata****:**

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****.**

**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****.**

**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.**

**Again, Find number of bricks per CuM:**

**= 1/0.0011848 = 541 nos.**

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.**

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

**f****or**** 0.24 ****CuM**** ****of**** ****mortar**** .**

**1**

**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****.**

**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.**

**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**

**Cement: 1.5 bags**** ****x**** 4 = ****6 ****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****.**

**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: **** ****6 ****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**

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.**

Its really a fun.

believe me.

**Happy journey on the path of estimations.**

# Throw the stone…carefully.

**Overview:**

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****.**

**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.

**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)**

**A cross stone called as Header**is provided

**across the wall**to give a binding on the wall 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.