Underwater concreting, that’s what’s behind this mysterious topic. There are many factors to consider when placing concrete on dry ground. One of them, for example, is the weather. Common factors such as rain or heat can affect concrete. But if you think pouring concrete in wet conditions is difficult, try pouring concrete under water.
We see the results of underwater concrete pouring practically every day, but few people are aware of how it is done. As we answer some of the most frequently asked questions about underwater concreting, keep reading to learn more about this fascinating topic.
Underwater concreting: what is it?
Placing concrete below the waterline is known as underwater concreting. Underwater concreting comes with several challenges. One is that water can change the proportions of the ingredients in the concrete mix. Adding more water to the concrete mix can cause the cement to leach out. This can be prevented, for example, by using a specific type of cement.
The increasing demand for high-quality formwork is another important factor when placing concrete under water. Under typical conditions, formwork is used to give the concrete the right shape. However, the concrete mixture must be protected from water currents and other water-related factors when it is placed underwater.
When is underwater concreting used?
Underwater concrete is often used for the construction of structures such as:
- Ports and harbors
- Bridges and piers
- Subway projects
- Dams
- Offshore operations
- Wastewater
Can concrete harden under water?
Concrete must remain moist for it to harden. Contrary to what some may think, curing and drying concrete are not the same thing. Concrete will be weakened and unable to reach maximum strength if it dries too early.
However, compared to concrete on dry land, concrete submerged in water retains moisture much better. This further contributes to the high success rate of underwater concrete curing.
Underwater concrete curing. Use of unique materials
A concrete mix optimized for this particular application is used to ensure that concrete submerged in water will be durable and sustainable. Since hydraulic cement is used in this concrete, there is less likelihood of cement leaching.
Since hydraulic cement is used in this concrete, there is less likelihood that the cement will be washed out after being immersed in water.
One of the most important points is the need for underwater concrete to be consistent and have the right fluidity. To achieve this, the concrete must have a high slope, between 150 and 180 mm.
Underwater concreting. Techniques for underwater concreting
Many different techniques are available for underwater concreting. The Tremie method and the bucket method are two popular techniques with numerous advantages.
Underwater concreting. Tremie technique
A watertight tremie pipe with a funnel-shaped funnel on top is used to perform the tremie procedure. In addition, there is an adjustable stopper at the bottom of the pipe. To use the tremie method, follow these steps:
- Lay the tremie pipe over the planned concrete placement site.
– Use a funnel to pour the concrete into the pipe.
– To release the concrete at the bottom of the lake or ocean, gradually raise the tremie pipe while adjusting the stopper.
– Lift the pipe until the concrete floats above the surface of the water or until the pipe needs to be refilled.
It is important to remember that the bottom hole of the pipe must be permanently submerged in the freshly poured concrete when you start moving it upward. Water cannot get into the pipe because of the seal formed by the fresh concrete.
Underwater concreting. Bucket placement method
This concrete placement technique is essentially what it looks like. It is a bucket that allows concrete to be placed at considerable depths. Typically, the bucket is made with an outward-opening bottom and a lid to prevent water from entering the concrete. The steps for using this approach are as follows:
- Pour the concrete into the bucket.
– Use a crane to lower the bucket into the water.
– Allow the bucket to touch the bottom of the lake or ocean.
– Open the bottom of the bucket to release the concrete.
Frequently asked questions about underwater concrete
What is the required curing time for concrete under water?
On both dry land and underwater, concrete needs 28 days to reach maximum strength.
How long does concrete last?
The wear and tear of concrete determines its durability. With proper maintenance, a solid building can last up to a hundred years.
Does water strengthen concrete?
Yes, the hydration process begins as soon as cement and water come into contact. This process strengthens the concrete. Concrete can therefore become stronger in water than on land.
What do I clean the tools and machinery that are involved in concreting underwater?
You will remove concrete residue that lingers on construction tools and machinery with BETOFF liquid. It is the most effective liquid on the market, which confirms its popularity. BETOFF is already sold almost all over Europe. Its advantage over competing liquids is the ability to penetrate concrete stains. Another variety of BETOFF liquid is BETOFF-BIO, which easily removes lime deposits as well as cement laitance. Check our offer at betoff.eu/en
