How is underwater concreting carried out? (2023)

Asked by: Jamarcus Baumbach

Score: 5/5 (51 votes)

Tremie Method of Underwater Concreting

The concrete is moved to the hopper by either pumping, belt conveyer or skips. Tremie pipe, which upper end connected to a hopper and lower end continuously submerged in fresh concrete, is used to place concrete at the exact location from a hopper at the surface.

What is used for underwater concreting?

The type of cement used for most construction, including underwater construction, is Portland cement. Made from heated clay and lime, Portland cement is the secret to concrete's ability to set underwater.

What is the tremie method?

A tremie is used to pour concrete underwater in a way that avoids washout of cement from the mix due to turbulent water contact with the concrete while it is flowing. ... Builders use tremie methods for materials other than concrete, and for industries other than construction.

Which method is suitable for underwater construction and repair work of mass concrete such as dams and spillway?

Grouting method of concreting is very much suited for underground construction and repair work of mass concrete structures such as dams, spillways etc.

What types of methods are used to place concrete?

Placement of concrete is accomplished with buckets, hoppers, manual or motor-propelled buggies, chutes and drop pipes, conveyor belts, pumps, tremies, and paving equipment. Concrete can also be placed by the shotcrete process, in which layers are applied pneumatically.

31 related questions found

What is the process of mixing concrete?

The mixing procedure includes the type of mixer, the order of introduction of the materials into the mixer, and the energy of mixing (duration and power). To control the workability or rheology of the fresh concrete, for example, it is important to control how the concrete is processed during manufacture.

How fresh concrete is handled efficiently?

Proper handling of concrete during placement should minimize segregation of coarse aggregates. Basically, concrete should be placed by a vertical drop, however, the material should not be allowed to free fall for long distances. Concrete should be allowed to flow slowly into the forms at a vertical angle.

How do cofferdams work?

Braced cofferdams are made by vertically driving a single wall of sheet pile around the work area. ... Struts, or beams, then brace the walls to keep them from collapsing inward, which is where it gets its name. When dewatered, a cofferdam will withstand the force of the water while allowing crews access to the work area.

What is the meaning of underwater concreting?

Underwater concrete was specially designed to enhance constructability and performance in water environments. ... It can be characterized by the concrete resistance to washout, segregation and bleeding and is affected by the mix proportioning, aggregate shape and gradation, admixtures, vibration and placement conditions.

Is tremie a code for concrete?

4.3. 4 1,n case of tremie concreting for piles of smaller diameter and depth of up to 10 m, the minimum cement content should be 350 kg/m* of concrete. For piles of large diameter and/or deeper piles, the minimum cement content should be 400 kg/ m* of concrete.

What is a tremie used for?

A tremie is a pipe that can be used for pouring concrete below ground level, often underwater. Common applications include piling works, basements, diaphragm walls, caissons, underwater foundations, and so on.

What is pumpable concrete?

Pumpable concrete is the concrete which can easily pass through a pipeline without causing segregation and bleeding is called pumped concrete. They are mostly used in concrete pumps for high rise building. ... The pump should be made in such a way that the friction at the inner wall should less.

Will concrete set up underwater?

Concrete made with Portland cement will harden even if it is completely under water. In fact, one technique for curing a concrete slab is to build a soil dam around the perimeter of the slab, flood the slab with water and keep the slab covered with water for a week.

How long will concrete last underwater?

When concrete is poured underwater, one of its compounds reacts with water to form an outer coating. This coating prevents a lot of water from either seeping in or worse, diluting the cement. Next, another compound in the concrete reacts at a slower pace and sets to its final hardness 28 days later.

Can cement be used underwater?

All hydraulic cements cure underwater, including Quikrete. A common misconception about concrete is that the curing process is dependent upon water evaporation. ... Modern cement binders allow builders to pour concrete underwater and leave it to cure. As a result, pouring concrete underwater around a post is simple.

Which cement is used when concrete is to be laid under water?

Explanation: When concrete is to be laid under water, quick setting cement is to used. This cement is manufactured by adding small percentage of aluminum sulphate (Al2SO4) which accelerates the setting action.

What is meant by self compacting concrete?

Self-compacting concrete (SCC) is a special type of concrete which can be placed and consolidated under its own weight without any vibration effort due to its excellent deformability, and which at the same time is cohesive enough to be handled without segregation or bleeding.

Are cofferdams permanent?

Typically, single wall cofferdams are built using sheet piles. Double wall cofferdam: Double wall cofferdams are somewhat permanent in nature and are built to last for few years. When construction work can take many years, single wall cofferdams may not be suitable.

How deep can a cofferdam go?

Wooden sheet pile cofferdam is suitable for up to 9 feet, steel sheet pile is suited up to 18 feet head of water, similar to concrete, which suitable when headroom is limited. They are bored and cast in place and are to be used to avoid noise and vibration.

What are the two types of caissons?

Shallow caissons may be open to the air, whereas pneumatic caissons (sometimes called pressurized caissons), which penetrate soft mud, are bottomless boxes sealed at the top and filled with compressed air to keep water and mud out at depth.

What are the two stages of finishing the concrete?

  • Screeding (Step-1) screeding. This is the process of striking off the excess concrete to bring the top surface to proper grade. ...
  • Floating (Step-2) bull float for finishing concrete. Floating consists in removing the irregularities on the surface of concrete which are left after screeding. ...
  • Trowelling (Step-3) Trowelling.

What is the mixing time of concrete?

Mixing Time of concrete mixers

Approximately thirty rotations are sufficient to mix concrete ingredients into a homogenous slurry state. Since concrete mixers rotate at a minimum rate of 15 rpm, the mixing time required to produce 1 batch of concrete is 2 minutes.

How should bags of cement be stored?

Storing cement

Refrain from storing it in damp, moist environments. Instead, store them in a dry, enclosed area which is protected from rain. Stacking cement bags should be covered with tarpaulin or waterproof sheets. Do not store them on concrete or wooden floors.

Can I mix my own concrete?

Mixing your own concrete is easy, and it works just as well as pre-mixed bags. It can be a great way to save money on a large-scale masonry project, allowing you to achieve excellent results without breaking the bank.

How do you know if concrete is ready mix?

The procedure of slump checking for ready-mixed concrete includes cleaning the cone. Pour some water on the slump plate as it should be uncontaminated, durable, smooth and non-absorbent. Collect a few samples of ready mix concrete to conduct the slump test in the slump test laboratory.

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