What is the purpose of keeping tremie pipe’s tip immersed in freshly-placed concrete for about 1m in underwater concreting?

  What is the purpose of keeping tremie pipe’s tip immersed in freshly-placed concrete for about 1m in underwater concreting? The size of tremie pipe is about 300mm with sections having flange couplings fitted with gasket to prevent water leakage. The tremie pipe should be closed initially to prevent water from entering the pipe. It should be designed with sufficient thickness and weight so that it would not be buoyant when empty inside water. The placement of tremie concrete is commenced by putting the closed pipe underwater to the location for concreting, followed by partial filling of tremie pipe with concrete. In order to have tremie concrete flowed out of the pipe, it is necessary to fill the pipe with concrete of sufficient height to overcome the water pressure and frictional head. After that the tremie pipe is raised about 150mm to allow concrete to flow out. To enhance sufficient bonding, each succeeding layer of concrete should be placed before the preceding layer has rea...
Post a Comment

WHAT IS GENERAL REQUIREMENTS FOR BUILDING DRAINAGE SYSTEM???

PLUMBING                              

1)    Water  Supply, Drainage And Sanitation

Water supply, drainage  and sanitation  form  the  main  components  of  normal  plumbing  work  on  a  housing project.

2)    General   Requirements  For  Buildings

All premises intended for human habitation, occupancy or use shall be provided with the supply of potable water which is neither connected with unsafe water supply nor subject to the hazards of backflow or back-siphonage.

Plumbing fixtures, devices and appurtenances shall be supplied with water in  sufficient volume and at pressure adequate to enable them to function satisfactorily under all normal conditions of use.

Plumbing shall be designed and adjusted  to use the minimum quantity of water consistent with proper performance and cleaning.

Devices for heating and storing water shall be so designed and installed as to prevent dangers from explosion through overheating.

Every building having plumbing fixtures installed and intended for human habitation occupancy or use on-premises abutting on a street alley or easement in which there is a public sewer, shall have connection with the sewer.

 3)    Water  Supply  Requirements

 Water requirements for drainage and sanitation for residences and buildings are given below:

Type  of building

Daily  per  capita  consumption ( Litres)

 

Residential

135

Offices

45

 

4)    Drainage  And  Sanitation  Requirements

There shall be at least one water tap and arrangements for drainage in the vicinity of each water closet or group of water closets in all buildings.

5)    Gradients  And Pipe  Sizes

Sewers shall be designed for discharging three times the dry weather flow flowing half-full with a minimum self-cleansing velocity of 0.75m/sec. The approximate gradients which give this velocity for sizes of pipes likely to be used in building drainage and the corresponding discharges when flowing half-full are as follows:

Sr. No.

Pipe  diameter 

(mm)

Gradient

Discharge

  (cum / min)

1

100

 1  in  57

0.18

2

150

1  in  100

0.42

3

200

1  in  145

0.73

4

230

1  in  175

0.93

5

250

1  in  195

1.10

6

300

1  in  250

1.10

 In cases, where it is practically not possible to conform to the ruling gradients, a more  flat  gradient  may  be  used  but the minimum velocity in such cases shall, on no  account,  be less than 0.61 m/sec. It is undesirable to employ gradients  which  result  in velocities greater than 2.4m/sec.

The approximate gradients which give a velocity of 2.4 m/sec. for the various sizes of pipes and the corresponding discharge when flowing half-full are as follows:

Sr No

Pipe  diameter 

(mm)

Gradient

Discharge

  (cum / min)

1

100

1  in    5.6

0.59

2

150

1  in    9.7

1.32

3

200

1  in  14.0

2.40

4

230

1  in  17.0

2.98

5

250

1  in  19.0

3.60

6

300

1  in  24.5

5.30

The discharge values corresponding to nominal diameter and gradient given in above-mentioned tables  are based on Manning’s  Formula (n=0.015). 

Minimum  Pipe  Size

Minimum size of pies shall be 100 MM. The sizes of pipes shall be decided in relation to the estimated quantity of flow and the available gradient.

6)    Choice Of  Materials  For  Pipes

Drainage  pipes  may  be  made  of  salt-glazed  stoneware,  cement  concrete,  cast  iron, asbestos  cement, lead, unplasticized  PVC  or  high  density polyethylene.

7)      Salt-Glazed  Stone Ware  Pipes

For sewers and drains, glazed stoneware pipes shall be used, as far as possible, in preference to other types of pipes. These pipes are suitable where acidic effluents or acidic subsoil conditions are likely to be encountered. IS 651-1971 gives specifications for salt-glazed stoneware pipes.

 8)    Cement  Concrete  Pipes

Cement concrete pipes with spigot and socket or collar joins are a good alternative to  salt  glazed stoneware sewers over 150 mm in diameter. However, these are not be used to carry acid effluents or sewage under conditions conducive to production of hydrogen sulfide and shall not be laid in those  subsoils which are likely to adversely affect  the quality or strength of concrete.

Cement  concrete water pipes conforming to IS: 458-1971 maybe used for surface water drains in all diameters. Life of cement concrete pipe may be increased by lining inside of the pipe by suitable coatings like epoxy/ polyester resins etc.

 9)    Cast  Iron  Pipes

Cast iron pipes, conforming to IS 1536-1967 and IS 1537-1960, shall be used in the following situations  :

Ø  In  unstable ground  where soil movement is expected,

Ø  In made-up ground

Ø  In conditions where increased strength is required for a sewer laid at insufficient depth or where it is exposed or where it has to be carried on piers or above ground.

Ø  In conditions where pipes have to be suspended on  below  ceilings  of  floor  slabs.

However, even when given a protective paint coating is given to cast iron pipes, these are liable to severe external corrosion in certain soils such as soils permeated by peaty waters and soils in which the subsoil contains appreciable concentration of sulfates. Suitable external wrapping of the pipes may be resorted to as an adequate safeguard.

 10)   Asbestos  Cement  Pipes

Asbestos cement  pipes conforming to IS 1626-1960 are commonly used for house drainage systems and are not recommended for underground situations or where encasement is to be done.

11)  Lead  Pipes

Soil, waste  and  anti-siphonage  pipes which branch from fittings to main stacks may be of lead  and  must conform to IS 404-1962.

 12)   Unplasticised  PVC  Pipe

Pipes conforming to IS 4905 - 1968 may be used for drainage purposes. However, where hot water discharge is anticipated, wall thickness should be at least 3mm irrespective of the size and flow load.

 13  High  Density  Polyethylene  Pipes

High-density polyethylene pipes and  fittings shall conform to IS 4984-1972 and  IS 8008-1976  for use in potable water supply.

 14)  Building  Inserts For  Drainage Pipes

Drainage pipes shall be kept clear of all other services.  Provision  shall be made during the construction of the building for the entry of drainage pipes.  In most cases, this may be done conveniently by building sleeves or conduit pipes into or under the structure in appropriate positions. This will facilitate the installation and maintenance of the services.

 15)  Manholes

At every change of alignment, gradient or diameter of a drain, there shall be a manhole or inspection chamber.  The maximum distance between manholes shall be 30 m.  Inspection chambers shall be such size as will allow necessary examination or clearance of drains. The minimum internal sizes   and  wall thicknesses  of chambers  shall be in as follows :

Sr No

Depth (mm)

Minimum  internal  dimensions (mm x mm)

Minimum wall  thickness (mm)

1

Upto  1000

800  x 800

200

2

1000 to 1500

1200 x 900

200

3

Above  1500

1200 x 900  or  1400 dia

300

Thicknesses  of  base  concrete  for chambers of different depths shall be as follows :

Sr No

Depth

 (mm)

Thickness  of  base 

concrete  (mm)

1

Upto  1000

150

2

1000  to  2000

200

3

Above  2000

300

 16)  Check List  For  Piping  Work

ENGG / FR / 


 

Work-site:

 

Check  List  For  Piping  Work                       Report  No:              Dated:

 

Sr  No

Parameter

Observation

1

Job

 

2

Contractor

 

3

Type  of pipe specified

 

4

Check the brand of pipes

 

5

Location  and  use

 

6

Check  quality  of  material

 

7

Check  dimensions

 

8

Check  level / gradient / alignment

 

9

Check the bedding of pipes

 

10

Check  joint  as  specified

 

11

Check the brand of solvent used to fix pipes

 

12

Check  fittings  and specials

 

13

Check  hydraulic test at 1.5  times  normal  head

 

14

Check the wrapping of hessian with a bitumen coating to pipes

 

15

Check the wrapping of insulating thread for pipes carrying hot water

 

16

Check the outlets for all spouts as per tile module

 

17

Check that after completion of work all the outlets are closed to prevent any material to enter in the pipes

 

18

Proper closing of chased portion after alignment is done

 

19

Check  painting

 

20

Check  supports

 

Other  comments :

 

Contractor’s  Engineer:

Site Engineer:

 17)  Check List  For  Manholes   And   Inspection Chambers

ENGG / FR / 


 

Work-site:

 

Check  List  For Manholes and Inspection  Chambers

Report No:                                                                              Dated:

 

Sr  No

Parameter

Observation

1

Job

 

2

Contractor

 

3

Type  of  manhole  specified

 

4

Location  and  use

 

5

Size  specified

 

6

Type  and  quality  of  cover

 

7

Check  masonry

 

8

Check  plastering

 

9

Check  levels  of incoming and  outgoing  pipes

 

10

Check  rungs

 

11

Check  finish  level

 

Other  comments :

 

Contractor’s  Engineer:

Site Engineer:

 

 


Comments

Post a Comment

Popular posts from this blog

What Is GGBS ?? What is the advantage of using GGBS as replacement of cement in concrete??What Is The Differences Between GGBS and PFA

What is GGBS?? GGBS (ground granulated blast furnace slag). What is the advantage of using GGBS as replacement of cement in  concrete? From structural point of view, GGBS replacement enhances lower heat of  hydration, higher durability and higher resistance to sulphate and chloride  attack when compared with normal ordinary concrete. On the other hand, it  also contributes to environmental protection because it minimizes the use  of cement during the production of concrete. However, it is identified that there are still some hindrances that prevent the  prevalence of its usage in local market. Technically speaking, GGBS  concrete suffers from lower rate of strength development which is highly  sensitive to curing conditions. In this connection, certain site measures  have to be introduced to the construction industry to ensure better quality  of curing process in order to secure high quality of GGBS concrete. On the  other hand, des...
Read more

DOOR FRAME // POINTS TO BE CONSIDERED AND CARE TO BE TAKEN WHILE ERECTING THE DOOR FRAME//HOW TO CALCULATE DOOR FRAME HEIGHT

Image
FOLLOWING POINTS TO BE CONSIDERED AND CARE TO BE TAKEN WHILE ERECTING  THE DOOR FRAME: 1) Before fixing of door frame, apply black Japan (coal tar) over the rough surface of the door frame which is touching to the RCC member/block masonry and  Primer to be applied on finished surface of door frame, if painting coming on  the door frame, so that application of black Japan (coal tar) and primer to be  done at ground level only. Do not take materials up without application of black  Japan (coal tar) and primer.   2) Different types of Holdfast and their uses. 3) Fix the hold fast to the door frame for both 7’ & 8’ door frame as per given  figure for different situation of block masonry. 4) Sometimes door frames width may be same for different locations i.e. Kitchen  and Bedroom, but Rebate size may be different. For eg. Kitchen door frame  Rebate = 47mm,& Bedroom door frame Rebate = 42mm. Hence one has to  ensure that door frame of ...
Read more

BLOCK MASONRY STEP BY STEP PROCEDURE...WHAT IS H/B RATIO

Image
BLOCK MASONRY Generally we are using in both residential and commercial buildings Hollow and Solid Block masonry as per site requirement.   Specification And General Guidelines For Block Masonry 1) Before starting any block work, prepare masonry layout on Typical Floor Plan  (Architecture Plan/ Chaapkam drg.). Thickness of each wall to be marked on plan in  different colours (Legend Type) and to be approved by the Project Incharge. Drawing is prepared before starting of first slab to put Electrical Conduits. 2. For H/B Ratio for less than or greater than 4 meter long masonry wall, the specs are given in below Para’s. 3. At the time of deciding the thickness of block for that particular wall, note that H/B ratio should not be greater than 20 for all walls less than 4 meter in length & for wall which is greater than 4 meter in length, H/B ratio should not be greater than 18. Where H = Height of block masonry and B = breadth of block masonry...
Read more