This document discusses techniques for underwater concrete construction. It covers topics such as concrete specifications, laying techniques using methods like tremie, bucket placing, and pump placement. Tremie placement is described as the standard method, involving pumping concrete through a watertight pipe. Concrete mixes for tremie placement require workability additives and a maximum aggregate size of 20mm. Repair works are also discussed, involving defining the repair area, cleaning, haulage, inspection, and environmental considerations.

1. BANGALORE INSTITUTE OF TECHNOLOGY
DEPARTMENTOFCIVIL
ENGINEERING
UNDER THE GUIDEANCE
OF
B S KARTHIK
Asst.professor
PRESENTED BY
AGNESH B S
1BI11CV008

2. Topics coveredTopics covered
Introduction
Concrete specification
Laying techniques
Repair works
Conclusion

3. IntroductionIntroduction
There are often situations such as basements ,
sewerage ,ducts , harbours , bridges and marine works ,in
which concrete is to be placed underwater.
Special precaution need to be taken whenever the
concrete is to be placed underwater.
The concrete should be plastic and cohesive but should
have good flowability.

4.  Performance requirements for UWC
Workability & self compaction
Cohesion against washout & segregation
Low heat of hydration
Controlled set time
Compressive strength
Adequate bond
 Problems faced
Segregation of fine aggregates from coarse aggregates
Water pollution
Increased w/c ratio
washout

5. Types of Materials usedTypes of Materials used ::
Cement
 Coarse Aggregates
 Fine Aggregates
 Admixtures

6. CEMENT :CEMENT :
Types of cements used in UNDERWATER CONCRETING
:
Ordinary Portland Cement (OPC)
Sulphate Resisting -Portland Cement ( SRPC )
Low Heat - Portland Cement ( LHPC )

7. AGGREGATESAGGREGATES :
Coarse Aggregates :
The coarse aggregate for intruded in concrete
shall conform to the following gradation:
Maximum Size - 1.5-2 inch (100% shall pass a 75
mm sieve )
Minimum Size - material passing a 19 mm sieve
shall not exceed 5% by mass of the coarse
aggregate.

8. Fine Aggregates :
 The sand for the intruded grout shall be well
graded, preferably of round grains and shall
conform to the following gradation:
 Passing 1.18 mm sieve 95 - 100%
 Passing 600 um sieve 60 - 85%
 Passing 300 um sieve 20 - 45%
 Passing 150 um sieve 15 - 30%
 Passing 75 um sieve 0 - 10%

9. Use of Different AdmixturesUse of Different Admixtures
Anti-washout admixtures
Hydrocem
 Mellose
Viscosity modified admixtures
Naphthalene Formaldehyde
Sulfonated Melamine Formaldehyde

10. Concrete Particles with adding MELLOSE
Concrete Particles without MELLOSE
* Black Dots
Indicates Water

11. Concrete laying techniquesConcrete laying techniques
Tremie method
Bucket Placing
Pump method

12. TREMIE METHOD
A Tremie is a watertight pipe
Generally 250mm in dia.
Funnel shaped hopper at its upper end
and a loose plug at the bottom.
It is supported on a working platform
above water level.

13. Specifications of concrete to
be used in Tremie method:
Coarse Aggregate: Gravel of 3/4” (20mm) max. size. Use
50-55 % of the total aggregate by weight.
Sand, 45-50% of the total aggregate by weight
Water/Cement Ratio: 0.42 (0.45 Maximum).
Water-Reducing Admixture (preferably it is also
plasticizer): Do not use super plasticizers.
Air-Entrainment Admixtures: To give 6% total air.
Retarding Admixture: To increase setting time to 4-24
hours, as required.
Slump: 6 1/2" ± 1"
This mix will develop compressive strength in the range
of 5,600 – 7,000 psi at 28 days.

14. Laying of concrete by using Tremie
14
Basic principle behind Method
of underwater concreting -
Tremie method
Method of underwater
concreting— Tremie
method (inside view)

15. Divers Using Tremie Concreting

16. Bucket placingBucket placing

17. PUMP METHOD:
Pumping concrete directly
into its final position,
involving both horizontal
and vertical delivery of
concrete.
Pumping concrete has the
advantage of operational
efficiency with potential
savings of time and labour.
17
PUMP METHOD OF
LAYING CONCRETE

18. Repair worksRepair works
Defining the Area
Cleaning the Affected Area
Equipment Haulage
Personnel requirements
Inspection methods
Environment considerations

19. At present, the Tremie placement method is
the standard way of placing high-quality
concrete underwater. The other placement
method are not able to reliably place high-
quality underwater concrete for major
structures, although they may find
application in special cases.

20. ReferencesReferences::
www.ce.berbley.edu/~parmont/165/tremie
www.vulcanhammer.net
www.ce.gatech.edu/~kk92/classpress/uwater/in
dex.htm
www.scanecm.com.au/products/additives/hydr
ocem/index.htm
www.ce.ecn.purdue.edu/cem/cliproj/civil/mello
se.htm
www.masterbuilder.com/uc.htm