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What Does MPA Mean In Concrete?

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So What Does MPA Mean In Concrete?

A megapascal (MPa) is a measure of the compressive strength of concrete. It lets inspectors know how much pressure can be applied to the concrete before it cracks or fails. Concrete is measured by its strength capacity. MPa (megapascals) is the metric measurement for psi or pounds per square inch. The BC Building Codes require a minimum MPa for specific concrete projects.

Footings, Walls, Foundations – 20 – 25 MPA
Interior Flatwork – 25 – 28 MPA
Garages, Carports – 32 MPA
Exterior Flatwork – 32 MPA

Please refer to the table below for MPA Levels and their Strengths.

MPA Concrete Strength Sydney

One MPa is equal to one million pascals (Pa); as a pascal is one newton of force per square meter, a megapascal is one million newtons per square meter.

If you have a project that requires a defined strength of concrete – i.e. 20MPa to set the posts for a raised deck – then it is time to call in the experts and have concrete delivered from a ready-mixed truck – It’s the only way to guarantee the structural strength in the concrete.

You may also see concrete requirements expressed as ‘N20/10’ – this is where N means normal class concrete, 20 refers to 20MPa of strength and 10 refers to it containing a maximum aggregate size of 10mm.

The English unit equivalent to MPa is pounds per square inch (psi). While the U.S., U.K., and a few other countries use psi, the majority of countries rely on MPa. Many manufacturers, builders, and suppliers provide product data showing both MPa and psi ratings for concrete materials. To convert psi to MPa, multiply the psi value by 0.0068915. For example, 2,500 psi = 2,500 x 0.0068915, or 18 MPa.

MPa ratings are used by a wide variety of building professionals. The structural engineer determines the required MPa rating for a structure based on the weight and load of the building and its occupants. Builders and contractors can then refer to MPa ratings when choosing materials, pouring concrete, and designing nearby building elements. Inspectors refer to MPa ratings when testing new concrete items, and concrete manufacturers may use these items when recommending products to clients. MPa ratings are also used in pre-engineered concrete facilities during the design and manufacture of precast concrete panels.

The MPa of new concrete is determined using a cylinder-testing process. Inspectors bore concrete cylinders after the surface has dried, or cured, for 28 days. The cylinders must be transported carefully to testing labs, where they are placed on testing machines. These machines usually consist of two heavy plates that are pressed together at either end of the cylinder; the machine subjects the concrete to extremely high compression forces until the cylinder cracks. Multiple tests are performed, and the average MPa is given to builders, engineers, and inspectors for review. If the MPa rating is lower than the design parameter, the concrete may need to be removed and re-poured.

Even more importantly, if the MPA is too low, that can actually influence your floor’s ultimate durability over the years. For that reason, we recommend a minimum of 32MPA for your floor, and if you want a Nil exposure look, we suggest 40mpa or 50mpa.

Low MPA concrete slabs may potentially cause:
– Potential Collapse of Pillars
– Cracks May Occur Easily
– Power Tools May Dent The Slab Easier

What Does MPA Mean In Concrete

20 MPa and 25 MPa compressive strength

    • Commonly used for house slabs, driveways, footings, and footpaths.

    • Residential slabs and footings

A default slump of 100 mm has been adopted by the premix concrete industry to reduce the uncontrolled addition of water on-site and make placing and compacting of concrete easier for concreters.

32 MPa, 40 MPa, 50 MPa compressive strength

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 that the concrete must support during its life

High strength: 65 MPa, 80 MPa, 100 MPa compressive strength

Commonly used for projects requiring high-strength concrete with options in design slump between 140 and 200 mm. 65 MPa concrete is available in 10 mm, 14 mm, and 20 mm aggregate sizes while 80 and 100 MPa are only available in 10 mm and 14 mm aggregate sizes. High-strength concrete is usually specified by engineers in applications such as high-rise buildings.Floor Levelling Sydney - Ardex Self Levelling Concrete - 14

Why Is MPA Important For Concrete Polishing?

If you do not want to see any stone whatsoever, you should choose 40MPa or even 50Mpa. This is known as Nil exposure and is considered to be the ‘Industrial look.’ In the simplest terms, the strength of the concrete refers to the hardness of the concrete. A Nil exposure slab needs to be much harder because when grinding, we need to be able to even out the concrete without immediately grinding too deeply. Otherwise, the stone underneath the stone may end up getting exposed, which will totally change the finish.

If you want to see some of the stone or a lot of it, then we recommend you choose 32MPa.

Some concreters offer 20MPa concrete, but that level is extremely soft where polishing is concerned. We always recommend a minimum of 32MPa 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 the years.

For that reason, we recommend a minimum of 32MPa for your floor, and if you want a Nil exposure look, we suggest 40MPA or 50MPa.

You might also want to be aware that for a Nil exposure slab, we have heard that it’s important for the concrete to use fresh water rather than recycled water because fresh water minimises the risk of discolouration. However, as we aren’t specialists in concreting, it is always best to check this with the concreter who pours the slabs.Concrete Polishing Floors Sydney - Concrete Polishing Sydney

Why Is MPA Important For Concrete Grinding?

What concrete hardness means for the concrete grinding industry is that the surface you are grinding will be either soft or hard. A 25 MPA concrete is very soft generally rain damaged and powdery and something that says 50 MPA which is very hard, generally curing compound applied or densified.

It’s really hard to tell until you start grinding the concrete.

– We recommend starting with a hard bond diamond and see if the grinding is quick enough.

– If too slow or not cutting at all, change to a soft bond but check the wear on the diamond after 10 mins or to make sure it’s not wearing too quickly.

A “Mohs Hardness Test Kit” can be used to also test the MPA of the concrete slab

The Mohs Hardness Test Kit is the perfect hardness tester for floors – to help choose the right diamond grinding tool for your job.

Mohs’ hardness is a measure of the relative hardness and resistance to scratching between minerals. Using the Mohs Hardness Tester Kit to determine the hardness or the scratchability of your concrete is useful for identifying the best diamonds to use on the job.

Once you have determined the hardness of the concrete you can make informed decisions about which diamonds to use without taking the risk they will wear out too fast or glaze over.

Taking the time to test your slab before grinding will allow you to get a longer grinding life out of your diamonds, saving you thousands of dollars in lost diamonds or unproductive work.

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