UNDERWATER CONCRETING
Prepacked Concrete(Grouted Concrete)
Prepacked Concrete
• Placing coarse aggregate only in forms and thoroughly compacting it to form prepacked mass.
• Mass is grouted with cement mortar of required proportions.
• Mortar grouts the concrete and displaces water and fill the voids.
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Requirements
• Well graded aggregate to produce dense and compact concrete.
• The aggregate should be wetted before being placed.
• Aggregates up to maximum size of 80 mm .• Fine sand, pozzolanic filler material and a
chemical agent.• An air entraining agent .
Methods of Grouting
• The mold is filled partially with grout and coarse aggregates can be deposited in the grout.
• The grout can be poured on top surface of the aggregate and allowed to penetrate to the bottom.
• Pumping the grout into aggregate mass from the bottom.
Benefits of Grouting
• The prepacked concrete exhibit lower drying shrinkage and higher durability.
• Resistance from freezing and thawing.• Rate of development of strength is slow but
eventual strength is same so it is used for underwater construction.
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