Where are post tensioned slabs used?
Where are post tensioned slabs used?
Post-tensioning now is used extensively in bridges, elevated slabs (parking structures and residential or commercial buildings), residential foundations, walls, and columns. Jim Rogers Bending and flexing creates high tensile forces that can cause the concrete floor slab to crack.
What is the Australian standard for concrete slabs?
In Australia, concrete slabs must be fixed in adherence with the Australian Standards AS 2870 and AS 3600. The most common slab thickness in Australia is between 85mm and 100 mm. The thickness of concrete slabs is usually stated in specification documents.
What is 30 MPa concrete used for?
This heavy concrete mix is usually used for creating external walls and slabs, as well as for structural piling. Used for: Commercial construction sites, creating foundations and beams for structural support and roads.
What is the difference between 20 MPa and 25 MPa concrete?
20mpa is weaker than 25mpa concrete, 32mpa and 40mpa concrete and so on. As a rule of thumb 20mph concrete is fine for foot traffic, I.e., footpaths and house slabs, depending on your sub base, whilst 25 mph is more appropriate for driveways and light traffic.
How common are post tension slabs?
The use of post tension cables has been around for many years. Back in the 1960 there was limited use in concrete foundations in residential construction, but very little. In states like California, Texas, Nevada and Arizona the use of post tension slabs have increased tremendously in the last ten years.
How do I know if my house is on a post tension slab?
How to tell if you have a post tension slab. Most homes that have post tension slabs have a sign that is stamped into a concrete garage floor, often near the edge of the garage door right in plain sight. Older homes with post tension slabs may have a plastic or paper sign fastened to the wall.
Which code is used in Australia for residential slabs and footings design?
BD-025 : Residential Slabs And Footings.
What are the two current Australian standards that cover residential slabs and footings?
The AS2870-2011 Residential Slabs and Footings Standard sets out a list of standard slab designs correlating to foundation soil types. This code provides designers with the most economical slabs/footing standards based on a number of criteria including both cost to the owner, and cost to the community.
Is 32 MPa concrete good?
We always recommend a minimum of 32 mpa because anything less can affect the level of gloss that is achievable. Even more importantly, if the mpa is too low, that can actually influence your floor’s ultimate durability over years.
What is 50 MPa concrete used for?
Concrete 50 MPa is commonly used in commercial and civil construction where high strength and durability are required. The mix will generally have a lower water to cement ratio than standard concrete.
What is 40 MPa concrete used for?
Concrete 40 MPa is commonly used in commercial and civil construction, for structural beams and columns, where increased durability and load-bearing capacity are required.
How long will a post tension slab last?
about 15-20 years
Conventional concrete & rebar foundations last about 20-30 years before failure begins to occur. Post-tension slabs are lasting about 15-20 years and are failing at a much higher rate. Post-tension slabs are created with concrete trenches around the perimeter of the house where the external walls will be placed.
Do post tension slabs crack?
Errors that lead to cracks in post-tensioned slabs As a result, even though post-tensioning is meant to help prevent a slab from cracking, the slab can still crack if the tensioning process is done incorrectly.
What year did post tension slabs start?
When was post-tensioned concrete first seen in this country? The first use was on the Walnut Lane Bridge in Philadelphia in 1949.
How long does post tension slab last?
How deep and wide do footings need to be Australia?
A concrete footing should be 100mm deep by 300mm wide if the footing is for a free standing wall. The footing should be increased to 150mm deep and 450mm wide if the wall being built is a retaining wall. For larger retaining walls an engineer may need to be approached for advice.
How deep are house footings Australia?
As a rule of thumb, the footing should be at least 30 cm deep and 1 metre long.
Is higher MPa concrete better?
32 MPa, 40 MPa, 50 MPa Higher strength is commonly used for concrete that will experience greater loads and traffic. This may be specified by engineers or builders to suit the load requirements which the concrete must support during its life.
How deep is a post tension slab?
A residential post-tensioned concrete slab will typically be 8 inches thick and use 3000 psi concrete. Once the concrete has gained strength to 2000 psi, typically within the 3 to 10 days recommended by PTI, the tendons are stressed.