Category Archives: RCC

Footings : Levelling Course & Water Logging :

Dear Friends ,

Let us solve the query of one of the readers today.

This is the query :

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In fact , there are two queries here :

  1. When do we use Plain Concrete in a footing ?
  2. Ground Water seepage during excavation ?

Let us solve these queries one by one.

First query is about the Plain cement Concrete .

Please have a look at the section of the Footing as given in the RCC drawing :

The PCC is marked here with Red :

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Now have a look at the base of a pit . This is how the surface shall be at the base of the excavation :

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It shall be very clumsy to lay the rebars on such a muddy surface. Right ? Thats why we provide a certain thickness of plain cement concrete here . This concrete is also known as the ” LEVELLING COURSE “.

So the Levelling course is a layer of Plain cement concrete which is given so that we get a good working surface for laying the footing properly. 

Now have a look at the leveling course laid on a site :

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Next step is to lay the Rebars of the Footings :

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Parallely , the shuttering for the footing is also fixed on the Levelling course.

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Now we do casting of the Footing so that it becomes the RCC footing .

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Hope the first query is clarified.

Now second query pertains to the Water logging during excavation.

You can have a condition like this on the site :

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So what do we do in such a case ?

Simple.

We have dewatering pumps and take out the water before laying the Levelling course :

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There might be a case like this also :

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So now , may be we shall have to wait for a dry spell so that this water either gets absorbed in the soil below or is evaporated.

In a situation , when the excavated pit is not completely dried, it shall not be possible to lay the plain cement concrete in the mud.

What do we do then ?

In such a case , we shall have to do Boulder solling so that we get a good ,

solid working surface .

Look at the stake of Boulders which are also known as Rubble or Stone :

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These boulders , when laid in the base of a pit , shall look like this :

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After this , the levelling course is laid in plain cement concrete. This is followed by the RCC footing.

Hope both the queries are clarified now.

Thank you for asking the queries .

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What is Bar Bending Schedule ?

Hello Friends ,

The Blog has recently achieved a status of having 850 Followers .

Various Initiatives are regularly planned for the engagement and enlightment of the readers.

One such initiative is ” On Line courses for Civil Engineers ” which have been commenced from Sept 2016.

Many students have benefitted through the Basic Module for construction .

” The On line courses “ is an appropriate medium for learning new concepts or for honing the skills without disturbing the routine activities .

Now presenting the On line course on “BAR BENDING SCHEDULE ” which was requested by many students for some time.
This article explains the course Objectives and other details you would like to know.

Hope you get registered for this course by 15th April 2017 .

Course begins from 20th April 2017.

All the best !

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You can also directly apply through this form below :

 

 

Really?  On line course? 

Hi Friends ,

Good Morning !

Hope you are all enjoying the season !

Have a look at this .

CATALOGUE.OLC.17.03.17. (1)

Look what the students of this course have to say :

One student expressed his joy :

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Another student :

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Look at why the students are joining this online course :

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Some other reactions :

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Another update :

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So, friends …what are you waiting for ?

You can receive  a sample Audio Visual PPT from me by mail so that you can have a feel of how the actual teaching takes place. Also let me know which is your preferred language .

The PPT slides are in English but the commentary can be either in English or Hindi or in Marathi . So that you can easily understand .

Write to me today itself .

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Santosh Kulkarni shared an answer on Quora with you

How much cement and steel are required for 50×23=1150 square feet and thickness of 4″? by Santosh Kulkarni https://www.quora.com/How-much-cement-and-steel-are-required-for-50%C3%9723-1150-square-feet-and-thickness-of-4/answer/Santosh-Kulkarni-37?srid=zM5g&share=5d914961

FOUNDATIONS…beginners guide

Dear Friends ,

Good evening !

The design and selection of a particular type of foundation is a work of the RCC consultant The construction person must know the background so that the interaction with the designer is easy. Read this article so that you know the basics.

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HOW TO MEASURE THE FORM WORK ?

Friends ,

Good Morning to all of you !

There shall be occasions when you shall have to measure the form work [ centering and shuttering ]. You may have to check a bill where the form work has been measured.

This article takes you through the initial examples of such measurements ..with pictures.

Read on :

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FOOTING COST on M.S. Excel ?

Dear Friends ,

It has been almost a week that we met here.

Today let us do something different. we have estimated the cost of a footing earlier. However, today we shall see how to carry out the same calculations using the M.S.Excel.

Ready ?

Before we begin , let me narrate the exact problem :

Estimate the material cost for a Box footing of dimensions  P*Q*R .

The Grade of concrete to be used is : M GG

 GG can be any value between 20 to 60  

[ This  means , it can be a concrete of any grade between M20 TO M60 ].

The material rates are as follows :

  1. Cement : Rs.CCC per bag
  2. Artificial Sand :Rs.SSS per brass
  3. River Sand :Rs.RRR  per brass
  4. Aggregate : Rs. AAA per brass 

The composition of River and Crushed sand is : X and Y. ( X +Y =100 or Y = 100-X )

[ This means that if we assume River sand factor X to be 50 % , The crushed sand to be mixed shall be 100-50 =50 % ]

The ReBars density in the given RCC is given as : DDD Kg/CuM.

[ For a footing , DDD = 80 to 100 Kg/CuM ]

Rate of REBARS  is : Rs. WWW per MT

Binding wire needed : B % of  DDD. [ As you might remember , B = 1 % to 2 % of the Rebars weight ]

Rate of Binding wire is : Rs. BW per Kg

The Plasticizer to be added is : PPP Ml/bag of Cement

Rate of Plasticizer is : Rs. PS per Litre

So now with this data , let us try a hand at the calculations with MS Excel :

  1. Open a new MS Excel sheet on your laptop or Desktop and prepare the following table :4
  2. The Volume of footing shall be  calculated automatically once we put numeric values for the dimensions
  3. Now , you already know how to arrive at the proportion of the Cement, Sand and Aggregate in a concrete if the grade has been given.
  4. Make a table like this :

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6.GIF

Once we put  the numerical value of the grade in place of GG , we shall directly see the factor of sand in the given grade .

Now , make the following table which shows the consumption of the materials in 1 CuM of concrete of the given grade :

7.GIF

And ….yes…you are ready with the basic template.

In this example , there are 15 variables :

  1. Footing Dimension 01 [ P ]
  2. Footing Dimension 02 [ Q ]
  3. Footing Dimension 03 [ R ]
  4. Grade of concrete [GG ]
  5. Composition of river and crushed sand [ X % & Y% ]
  6. Density of Rebars in the concrete [DDD ]
  7. Consumption of Binding wire [B%]
  8. Consumption of Plasticizer [PS]
  9. Rate of Cement [ CCC ]
  10. Rate of Crushed Sand [SSS ]
  11. Rate of River sand :[RRR ]
  12. Rate of Aggregate [ AAA ]
  13. rate of Binding wire [BW ]
  14. Rate of Rebars [WWW ]
  15. Rate of Plasticizer [PPP]

Now , let us say , on your site , the following values have been determined :

    1. Footing Dimension 01 [ P =1200 mm ]
    2. Footing Dimension 02 [ Q=1200 mm  ]
    3. Footing Dimension 03 [ R= 1200 mm ]
    4. Grade of concrete [GG =30 ]
    5. Composition of river and crushed sand [ X =50 %  & Y=50 % ]
    6. Density of Rebars in the concrete [DDD = 100 Kg/CuM  ]
    7. Consumption of Binding wire [B= 1 %]
    8. Consumption of Plasticizer [PS= 80 ml /bag ]
    9. Rate of Cement [ CCC = Rs 300 per bag ]
    10. Rate of Crushed Sand [SSS= Rs. 3800 per brass ]
    11. Rate of River sand :[RRR= Rs. 4600 per brass ]
    12. Rate of Aggregate [ AAA= Rs.2500 per brass  ]
    13. rate of Binding wire [BW= Rs. 50 per kg ]
    14. Rate of Rebars [WWW = Rs. 38000 per MT ]
    15. Rate of Plasticizer [PPP= Rs.100 per litre]
  1. Now we simply need to enter this data into the templates we made earlier in the examples :

8.GIF

The proportion of materials in the concrete is as follows :

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The composition of River and Crushed sand shall be :

10.GIF

Now , we need to just feed the data in the Summary template as follows :

11.GIF

Now suppose after a few weeks , your site reports to you that now the data has changed slightly due to various factors. And your boss wants you to re-calculate the cost.

Dont worry. You shall now need less than a minute to tell him the revised cost.

Let us say , the new data is as follows :

Values which have remained constant :

  1. Footing Dimension 01 [ P =1200 mm ]
  2. Footing Dimension 02 [ Q=1200 mm  ]
  3. Footing Dimension 03 [ R= 1200 mm ]
  4. Grade of concrete [GG =30 ]
  5. Composition of river and crushed sand [ X =50 %  & Y=50 % ]
  6. Density of Rebars in the concrete [DDD = 90 Kg/CuM  ]
  7. Consumption of Binding wire [B= 1 %]

Following values have been revised :

  1. Consumption of Plasticizer [PS= 85 ml /bag ]
  2. Rate of Cement [ CCC = Rs 310 per bag ]
  3. Rate of Crushed Sand [SSS= Rs. 3900 per brass ]
  4. Rate of River sand :[RRR= Rs. 4500 per brass ]
  5. Rate of Aggregate [ AAA= Rs.2400 per brass  ]
  6. rate of Binding wire [BW= Rs. 45 per kg ]
  7. Rate of Rebars [WWW = Rs. 37000 per MT ]
  8. Rate of Plasticizer [PPP= Rs.95 per litre] 

Just feed the new values in our Summary template :

12.GIF

Now you can promptly inform your boss that the rate of concrete has been reduced from Rs. 8404 per CuM to Rs.8388 per CuM.

Accordingly , the cost of the footing has come down slightly from Rs.14523 to Rs.14494.

So friends , with this template on your laptop , whenever , any of the data in the 15 variables is revised at site , you can proudly present the revised cost within a minute.

Hope you enjoyed this .

Please give me your feedback /suggestions through this form here :

Thank you so much !

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