Introduction of a wider range of more sustainable factory produced blended cement

As our business evolves to follow our roadmap to net zero and achieve our Future In Action objectives, employees and customers will see an ever-growing list of carefully controlled, ‘Factory Produced Blended Cements’. To help us all with the changes Richard Boult, Commercial Technical Manager for Cement, talks through the updates to the cement product range:

The latest addition to the CEMEX portfolio is our CEMSTONE bulk product and later this year packed Rugby High Strength will change in composition to include less clinker but maintain the same strength performance levels.

On this journey some of the technical jargon will also change and we will need to be careful over the type of language we use when referring to products.

The obvious way to be clear on what is being referred to is to use the ‘brand’ name, which should be reflected in the Product Description field of our despatch and invoice documentation. For example, our portfolio of bulk cement products is currently CEMEX Portland, CEMEX Extra and CEMEX Cemstone and our packed cement range (bearing the Rugby brand) is Rugby Premium, Rugby Sulfate, Rugby High Strength and Rugby White. More information on these products and their key benefits can be found at www.cemex.co.uk/cement-products

Often, we hear expressions such as CEMI and CEMII to describe these products with each one having its own proper technical description. And with more and more products on the way it is worth examining this naming convention in a little more detail.

The background to these strange descriptions lies within the Product Standard for Cement, “BS EN 197-1 Cement, Part 1 – Composition, Specifications and Conformity Criteria for Common Cements”.

Currently the standard contains technical descriptions for 27 ‘common cements’ although only a few are actually manufactured currently in the UK. Last year a further part of the standard (BS EN 197-5) was published which lists a further five possible ‘common cements’ although their use will only be allowed in structural concrete the UK in 2023 when the concrete standard is changed.

Currently cements are grouped into six types denoted by the word CEM followed by Roman Numerals (and not ordinary numbers):

– CEMI Portland cement

– CEMII Portland-composite cement

– CEMIII Blast furnace cement

– CEMIV Pozzolanic cement

– CEMV Composite cement

and now following the introduction of BS EN197-5:

– CEMVI Composite cement

Are you still with me?

CEMI is pretty straightforward as while all of these cements are allowed to contain a small amount of ‘Minor Additional Constituent’ it is made predominantly from clinker, the hard granular material manufactured in our kilns. However, as the types of materials (known as additions) that are allowed to be used to manufacture the other ‘blended cements’ (CEMII to CEM VI) are numerous there is a further layer of complexity used to describe in simple terms these other additions which in order are:

• Blast furnace slag (a by-product of steel production) denoted as S
• Silica fume (a by-product of silicon and ferrosilicon alloy production) denoted as D
• Natural pozzolana (a material found in quarries around Europe and worldwide which has reactive properties rather like cement often formed through volcanic activity) denoted as P
• Natural calcined pozzolana (often clays that have been pyro-processed in kilns) denoted as Q
• Siliceous fly ash (a by-product of burning the hard coals prevalent in Europe) denoted as V
• Calcareous fly ash (a by-product of burning coals containing a higher amount of calcium) denoted as W
• Burnt shale (a by-product of burning oil bearing rocks for fuel) denoted as T
• Limestone (a carbonaceous rock abundant in the Earth’s crust formed from the shells of ancient sea creatures) denoted as L or LL

Using this list of ‘additions’ the full technical description of any of the ‘common cements’ can be built up (refer to Table 1 in BS EN197-1 or BS EN 197-5). For example, in our case:

CEMEX EXTRA has the notation CEMII/B-V which means it is a Portland-composite cement containing 65-79% clinker (the meaning of the B here) and the addition being siliceous fly ash i.e., a Portland-fly ash cement

and

CEMEX CEMSTONE has the notation CEMII/A-LL which means it is a Portland-composite cement containing 80-94% (the meaning of the A here) and the addition being limestone i.e., a Portland-limestone cement

You can see then that simply referring to CEMII could end up with confusion over which product is being described. The full correct notation includes a sequence at the end to describe the strength class tested in a standard mortar at 28-days, and a letter to denote whether the early strength is ‘Normal’ (N) or ‘Rapid’ (R).

So, in the example above CEMEX EXTRA in full is BS EN 197-1 CEMII/B-V 42,5N Portland fly-ash cement, meaning its strength is between 42.5MPa and 62.5MPa at 28-days and it has a ‘normal’ early strength and CEMEX CEMSTONE is BS EN 197-1 CEMII/A-L 52,5N Portland limestone cement, meaning its strength is above 52.5MPa at 28-days. Note the use of a comma instead of a decimal point in the strength class, this is ‘Euro speak’.

At some point in the future, you are quite likely to see CEMII/C-M (Q-L) 42,5N or CEMVI/S-L 32,5R products in production. Answers on a postcard please if anyone can let me know the full description, constituent materials and cement type for these two products….

So, there you have it, cement naming convention in a nutshell. As technical descriptions are a bit of a mouthful, for our day-to-day business it is probably worth simply referring to the Brand Names given above and in the table as these are unique to each product, and this will avoid confusion. It’s probably worth a check to see if this can be improved in your local systems and procedures. If, however, colleagues and customers start talking about CEMI’s and CEMII’s please make sure they are using the correct form in full before you decide which product it is they are actually referring to.