View source for Construction-of-Low-Cost-Houses/C2/Laying-Foundation-bed-Concrete/English

'''Title of the Script''': Laying Foundation Bed Concrete 

'''Authors''': Dr. Narsingh Varma, Chitra Balaji and Madhuri Ganapathi 

'''Key words''': Concrete spreader, Float, Level water tube, Spirit level, Bump Cutter, Screed, Safety shoes, Hand gloves, laitance, hessian cloth, video tutorial.


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|| '''Visual Cue'''
|| '''Narration'''
|-
|| '''Slide Number 1'''

'''Title Slide'''
||Welcome to this Spoken Tutorial on '''Laying Foundation bed Concrete. '''
|-
|| '''Slide Number 2 '''

'''Learning Objectives'''
||In this tutorial we will learn about:

* What is foundation bed concrete.
* Materials and tools required for laying the concrete.
* Process of laying foundation bed concrete.
* Safety precautions and
* Quality check

|-
|| '''Slide Number 3'''

'''Pre-requisites'''

'''https://spoken-tutorial.org'''
||To practice this tutorial, learners should be familiar with basic construction methods.

For the prerequisite tutorials, please visit this site.
|-
|| '''Slide Number 4'''

'''Details of foundation bed concrete'''
||Let us now learn about general terms on foundation bed concrete.
|-
|| 
13. details of foundation bed

foundation bed

laying bed concrete 

||'''Foundation:'''

It is the lowest part of the building that is in direct contact with the soil.

It transfers load from the superstructure to the soil safely. 

Foundation bed:

The soil immediately beneath the foundation of a building is foundation bed.

In load bearing structures, PCC has to be laid at the foundation bed after excavation.

|-
|| '''Slide Number 5'''

'''Purpose of Laying PCC'''
||The purpose of laying of PCC at foundation bed is to:
Level the undular surface of excavated soil.

Provide firm surface to the foundation

More information on this is given in the '''Additional reading material'''.

|-
|| '''Slide Number 6'''

'''Materials and Tools Required'''

||Materials and tools needed for laying foundation bed concrete.

|-
|| copy of 1 ,copy of 2 copy of 5b, copy of 13.a

1.cement concrete

1a.cement concrete
||The materials are: Cement, sand, 20 mm and 10 mm coarse aggregates and water.

These ingredients are mixed in the ratio 1:3:6 to make plain cement concrete.

Concrete mix can vary as per local technical guidance and site conditions. 

|-
|| Narration

add text on plain base
||Tools required for foundation bed concrete. 
|-
|| 2.concrete spreader

2a.concrete spreader

2b.concrete spreader
||'''Concrete spreader'''

It is used to spread the concrete. 
|-
|| 3.float

3a.float
||'''Float''' 

Float is used to level and spread the concrete.

It is made of a wooden strip with a''' '''wooden handle.

|-
|| 4.Trowel
||'''Trowel'''

Trowel is a tool for leveling and finishing the concrete.

It is made up of a steel sheet with a wooden handle.
|-
|| 5.water level 
||'''Level water tube'''

It is a thin, transparent and flexible plastic pipe.

It is used to fix and mark the same height between larger distances.
|-
|| 6.leveller
||'''Spirit level'''

Spirit level is a tool used to check the surface level.

It indicates whether the surface is horizontal or not.
|-
|| 7.bump creed

7a.bump creed

bumpcutter 1 

bump cutter 2
||'''Bump Cutter '''or''' Screed'''

It is used to level fresh concrete surfaces 

Leveling is done by cutting bumps and filling the depressions. 

It is also used to compact concrete, especially plain cement concrete.

|-
|| '''Narration'''

'''Slide Number 7'''

'''Laying Foundation bed Concrete'''
||Let us see the steps involved in the process of laying foundation bed concrete.

* Preparatory work for bed concrete
* Side shuttering
* Laying of concrete
* Leveling and finishing 
* Curing of concrete

All provisions mentioned in this tutorial are according to Indian Standard (IS) codes.

|-
|| 10.Excavated pit

11.vibratory compactor

11a.vibratory compactor
||  '''Preparatory work for bed concrete.'''

Remove loose materials if any from the excavated pit.

Remove the top 10 cm soil, if the excavation was completed before.

In case of filled soil, check and consolidate soil using a vibratory compactor.

|-
||  12.side shuttering

width of excavation

width of excavation more

width of excavation more 1

13.Details of foundation bed

width of footing offset
||'''Side shuttering'''

Side shuttering helps to mould the wet concrete in place until it is set.

If width of excavation is more than the width of bed concrete then, side shuttering is needed.

side shuttering has to be provided at the required width of bed concrete.

Width of bed concrete is width of footing plus 8 cm offset on sides.
|-
|| 14.marking of shuttering

15. level tube

16. pouring of concrete

pouring of concrete 1 

pouring of concrete 2

17.spread concrete

17a.spread concrete
||'''Laying of concrete'''

Mark benchmarks of average 8 cm thickness from the base of the foundation pit. 

These markings are done at various locations along the excavated trench.

This is done using a water level tube, to ensure uniform laying of concrete.

The concrete mix is poured inside the foundation pit up to the marking.

Care has to be taken while pouring the concrete into the foundation pit.

The maximum permissible free fall of concrete should be 150 cm.

Spread concrete uniformly using hoe or spreader up to benchmark level.
|-
||  bump cutter1

bump cutter 2

19.latiance

20.sprinkle some cement

21.leveling

21a.21b.21c.

||'''Leveling and finishing'''

Remove local unevenness of concrete if any using a bump cutter.

Consolidate concrete using screed.

In case of formation of latiance, sprinkle dry cement over the foundation bed.

Compact the foundation bed again to make it uniform.Laying and leveling must be completed when concrete is wet.
|-
||  22.hessian cloth

23. watering

23a.watering
||'''Curing'''
Cure concrete by covering it with wet hessian cloth. 

Keep the cloth wet by watering for few days before starting the masonry work.

Curing must be continued till the start of masonry or minimum 14 days.
|-
|| 
24.personal protective 

gloves, gloves1 and gloves 2


24a.safety shoes

24b.specs

googles

try to fit googles and shoes and gloves in page

||'''Safety Precautions'''

Always wear personal protective equipment on construction sites.

Hand gloves provide safety to hands against construction chemicals.

Shoes provide safety to legs against the toxic effect of cement. 

Shoes also prevent physical injury to the legs.

Safety goggles prevent eye irritation from chemicals and concrete dust. 
|-
|| laying bed concrete

25.foundation bed level

26.segregation

27.bleeding

28.slump 

||'''Quality Check'''

Check the foundation bed level using spirit level.

It must be horizontal.

PCC must be free from segregation and bleeding.

Slump value of concrete should be 25 mm to 75 mm.

|-
|| '''Slide Number 8'''

Reference codes
||These are the reference IS codes.

IS 456 

IS 1904 

IS 1080 
|-
|| Only Narration.
||With this we come to the end of this tutorial.

Let us summarise.
|-
|| '''Slide Number 9'''

'''Summary '''

||In this tutorial we have learnt about,

* What is foundation bed concrete.
* Materials and tools required for laying the concrete.
* Process of laying foundation bed concrete.
* Safety precautions and
* Quality check

|-
|| '''Slide Number 10'''

'''About Spoken Tutorial project '''

||The video at the following link summarizes the Spoken Tutorial project.

Please download and watch it. 

|-
|| '''Slide Number 11'''

'''Forum for specific questions'''

||Please post your timed queries in this 

forum.
|-
|| '''Slide Number 12'''

'''Acknowledgement slide.'''
||The Spoken Tutorial Project was established by Ministry of Education, Government of India.

|-
|| '''Slide Number 13'''

'''Thank you '''

||This tutorial is contributed by Dr. Narsingh Varma, Chitra Devi and Madhuri Ganapathi from IIT Bombay

Thank you for joining.

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