What is tremie method of concreting?
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. This produces a more reliable strength of the product.
What is a tremie slab?
A tremie seal is a non-reinforced concrete slab anchored by piles against buoyancy and installed underwater by divers within sheet piling or slurry walls to control water intrusion. Typically, the perimeter sheet piling is installed, followed by anchored production piles.
What is tremie pipe method?
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. The reason to immerse the tremie pipe lower end is to prevent intermixing of both concrete and water.
What is the purpose of a tremie?
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. A tremie is made of rigid metal or plastic tubes, generally with a diameter ranging from 20 – 30 cm.
What is the recommended minimum diameter of a tremie pipe?
While placing concrete by tremie method, all tremie pipes should be cleaned before and after use. The diameter of tremie pipe should be preferably 200 mm for constructing piles of all diameters within 600 mm.
What is the slump used for Tremie concrete?
Slump: 6 1/2 in. ± 1 in. This mix will develop compressive strength in the range of 5,600 – 7,000 psi at 28 days.
What is the maximum height through which concrete can be poured *?
4. What is the maximum height through which concrete can be poured? Explanation: Concrete consists of coarse aggregates. If it is placed or poured from a height above 1 m, segregation of coarse aggregate will take place, leading to improper distribution.
What causes laitance?
Laitance is a weak, easily-crumbled layer on the surface of concrete, consisting of cement and fine aggregates that rise to the surface when too much water is added. Laitance may also be caused by over-trowelling, rain damage, or poor curing.
How is laitance formed?
Laitance is caused by bleeding of concrete. In case of bleeding, only water accumulates at the top of the surface, but in case of laitance, along with water certain quantity of cement also comes to the surface, forming a thin layer of cement paste at the surface.
How far can you drop concrete without it segregation?
Detailed Solution. Explanation: As per clause 13.2 of IS 456: 2000, the maximum permissible free fall of concrete to avoid segregation may be taken as 1.5 m or 150 cm.