Different Grades of Concrete explained …

Different projects often require different grades of concrete. In this instance, the grade is defined as the strength and composition of the concrete based on the minimum strength the concrete needs to be after 28 days following initial construction.  

C Grade concretes are measured using cubic concrete testing. This is where samples of concrete are taken from batch of concrete and tested to ensure the concrete is of suitable strength. A minimum of 3 cubes are taken from each sample, which are then stored in moist air for 24 hours.

The specimens are then removed from the moulds and submerged in water before being taken out and tested. C graded concrete shows the compressive strength of the concrete in newtons. For example, C20 concrete has 20 newtons of strength.  

Choosing the right grade of concrete for a job is essential as it can dramatically affect the concretes performance and suitability.

For example, larger structures have high strength requirements, therefore they require higher grades of concrete such C35 and above. 

Lower strength concrete such as C15 or C20 tends to be mainly used for domestic projects such as patio slabs, pathways, driveways and internal floor slabs whilst higher grade concrete including C30 concrete and above is mainly used for commercial projects such as roadways, bridges and external slabs.  

Other methods of grading concrete …

Sometimes concrete mixes are measured using a slightly differently ratio.

For example, you may often see references to M grade concrete. In this case the M stands for mix and represents the ratio between the cement, fine aggregate and course aggregate.  

M20 grade concrete, for example is made up of 1–part cement to 1.5 parts of sand (fine aggregate) and 3 parts aggregate. (gravel/crushed stone) M grade concrete is measured using a compressive strength ratio of MPa N/mm2 psi (pounds per square inch) 

M grade concrete is normally defined under two main categories, Nominal and design concrete. “Nominal” or regular concrete is mainly used for small scale construction and includes grades of concrete ranging from M15 to M25. Design mix is a higher strength concrete which is more suited to larger commercial construction. 

With design mix concrete, the mix ratios are decided by an Engineer and there is no pre-fixed ratio. Design mixes are usually used for larger scale and commercial construction. 

We produce a vast array of different grades of concrete to suit all projects both big and small from our state of the art Liebherr Concrete Plant in Whetstone, Leicester. 

To find out more contact us today.