By : Selvaraj Yogeswaren Mohamad Afiq Hezam Ali Logaswaran UNDER WATER CONCRETING
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
By :
SelvarajYogeswarenMohamad AfiqHezam AliLogaswaran
UNDER WATER CONCRETING
Under Water Concreting
Past Under Water Concreting UsageCurrent Under Water Concreting Usage
Under Water Concreting
•Current Under Water Concreting Usage…
•Method’s
•Problems
Under Water Concreting
…Method’s…
Anti-washout Admixtures (AWA)
Anti-washout Admixtures (AWA)
What are they ? Characteristics Uses Advantages Disadvantages Examples
What are they…?
Viscosity – modifying admixture Consist of long molecule chains Cellulose derivatives (most common)
› Welan hum› Hydropupropyl methyl cellulose
What are they…?
Non – cellulose derivatives› Polyethylene Oxide
Characteristics…
Improve cohesiveness› Resists bleeding› Reduce Segregation› Results in minimal loss of fines
Tremies…
Placement Method’s
› Bucket Placement› Tremie
Wet pipe Dry pipe
Tremies…
Tremies…
Mixtures for under water placement.
Mixture for under water concrete…
Anything that improves workability should be considered
Slump approximately 7in. MSA should be approx 1.5in – 2.0in FA should be 45% of total aggregate Use air-entraining admixture
Methods…
Concrete Bagwork Grounting preplaced aggregate Concrete mixed conventionally Placement by Jercuie
Problems
Segregation of FA from CA Water pollution from contact between
fresh concrete and surrounding water Increased water cement ratio Washout
Uses
Concrete in large, underwater placements› Offshore platforms› Docks› Harbors› Bridge Structures
Advantages
Workability is improved Set time, cure time, shrinkage & creep
are not affected Reduced chloride ion permeability
Disadvantages
Reduction in elastic modulus 80% - 100% of original
Reduction in strength› Compressive 75% - 100% of original› Fexural 84% - 100%
Example
Example
Hydrocem
RHEOMAC UN450
Mellose
Hydrocem - Properties
Power admixture Increases cohesiveness while
maintaining high workability Increases strength up to 39 times the
strength under water without admixture
Hydrocem – Test Results
Hydrocem Test
Results
Sample 2 : Concrete
With Hydrocem
Sample 1 : Concrete
With Silica Fume
All other variables constant
Strength of concrete outside of water after 28 days.
› Sample 1 : 35% stronger than sample 2
All other variables constant
Strength of concrete underwater after 28 days
› Sample 2 : 39 times stronger than sample 1
Mellose
Mellose
Mellose
Cellulose based admixture
Used by Koren Company on the Kwangan Great Bridge
Reomac UW - 450
Properties
More Information
Testing
Reomac UW - 450
Reomac UW – 450 Properties
Cellulose based admixture No affect on slump or setting time Useful for mortar or grouting where
mixtures have a high water cement ratio
Lessens strength when used out of water
Increases strength when used underwater
Reomac UW – 450 More Information
Air-entraining admixtures may be necessary to achieve desired air content
Pozzalans & WRAs are recommended to achieves maximum result.
Should be placed by pump ortremie.
Reomac UW – 450 Testing
Washout test – Determines relative amount of cement lost when concrete is exposed to a large amount of water.
Some Of The Example Of Under Water Concreting
Thank You
Related Documents
