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 BULKAGE OF SAND???


BULKING OF SAND:

The Increase In The Volume Of  Dry Sand Due To Absorption Of Moisture Is Called

BULKING OF SAND, Bulking Of Sand Depends On The Quality Of Moisture In

The Sand And Also The Size Of The Particles. Five To Eight Percent Of The Increase

In The Moisture In The Sand Can Increase The Volume Of Sand Up To 20 To 40 Percent. 

TEST PROCEDURE TO DETERMINE BULKING OF SAND:

A)      Apparatus: 

 1)      20 lits, 25 litres measuring boxes (Farmas). 

 2)      Bucket.

 3)      Measuring tape        

 B)     Material     :      Sand  & Water

 C)    Procedure  :

 1)     Fill sand loosely in 20 litres, Measuring box and level with wooden log.

 2)     Unload the measured sand in 25 litres measuring boxes.

 3)     Fill 20-litre box with water up to ¾ heights.

 4)     Unload sand from 25 lit box in water in 20 lit box and level properly.

 5)     Remove water from top of sand and measure the level of sand at 4 places and take average depth.

 6)       Calculate Bulkage using the following formula.

 7)        Bulkage (%) = X x 100 / d

                        Where d = Final level of sand

                                    D = Initial level of sand

                                    X = Average depth of Settlement

   

  D)      Sample Calculations:

             Bulkage (%) = X x 100 / d

             Where d = Final level of sand

                        D = Initial level of sand

                        X = Average depth of Settlement

                        d  = D - X

                         X = Average depth of sand = X1 + X2 + X3 + X4 / 4

                         X1  = 4.5 cms.

                         X2  = 4.5 cms.

                         X3  = 4.5 cms.

                         X4 = 4.5 cms.

        Therefore,

                         X = ( 4.5 + 4.5 + 4 + 4) /4= 4.25 cms.

                         d = D – X = 30 - 4.25 = 25.75 cms

       Therefore,

                         % Bulkage = [4.25 / 25.75] x 100 = 16.5 %

 8)             Observation/Conclusion:   As Per Sample Calculation, Bulkage = 16.5%.

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