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Incorrect construction of sand-cement screeds can lead to a multitude of failures such as de-bonding, cracking, crazing, poor abrasion resistance and ultimately, an unacceptable surface finish. We investigate the main reasons for such failures and offer expert advice that can help to eliminate it.

There is a common misconception that sand-cement screed flooring is more economic than finished concrete surfaces. As a result, screeds are often used for applications where concrete flooring would have been more appropriate. It is important to note that sand-cement screeds are only suitable for:

  • Light duty use; where there is no heavy point loads or abrasive traffic; and
  • As a levelling layer under covering such as tiles, carpet, wood flooring and vinyl.
Mix proportion specifications
The application of inadequate mix specifications is a major cause of failure in sand-cement screeds. It is therefore advisable to first consult a trusted industry guideline such as the pamphlets from TCI that are obtainable online at
According to this guide, the appropriate mix proportion is as follows: 1 x 50kg bag of cement: 130 litres (±150kg) of damp, loose sand.
Sephaku Cement also has a convenient cement calculator that enables you to quickly and easily calculate how much cement you will need to complete your project.

Material selection
Selecting the correct materials is a critical aspect of preparing to construct solid sand-cement screeds. This applies for all three the main components of the mix:
  • Cement: Only use CEM I, CEM IIA, CEM IIB and CEM IIIA cements with a strength grade of 32,5N MPa or higher. Click here to download a useful brochure to help you choose the right cement.
  • Chemical admixtures and additives: It is not common practice to use admixtures in screeding, but in instances where bonds, pigments or water-proofing agents are used, the manufacturers’ instructions must be followed to a tee.
  • Sand: The sand must be well-graded concrete sand of average to low water requirement. Plaster sands should not be used at all, as it typically has higher water requirements which weakens the mix and causes greater drying shrinkage that is the main cause of cracking.

Practices to avoid
A significant percentage of screed failures are also caused by bad practices that are handed over from generation to generation. Studies show that the primary issues are:
  • Poor surface preparation
  • Placing screeds on “dirty concrete” (oil, sand, debris, etc.)
  • Mixing too much screed too long in advance, instead of within an hour of use
  • Mixtures that are too dry and that cannot be compacted sufficiently
  • Floating of neat cement powder into the surface to dry and improve the finish
  • Floating of a cement/water slurry into the surface to “enhance” the finish
  • Incorrect and inconsistent batching

Finally and perhaps most importantly, it is imperative to provide for adequate temporary protection, as soon as the screed is completed. As it is a relatively thin and large surface, it allows for a lot of evaporation. For this reason, temporary protection such as plastic sheeting or curing compounds should be used to prevent premature drying. Special care must be taken to not make marks on the newly finished surface.

Lack of such protection in the early stage of development will compromise the integrity of the screed and may also void any manufacturers’ warranties that are in place. Generally trafficking should be avoided for the first 24-48 hours, but it is best to check the manufacturers’ specifications in this regard.

Industrial concrete floors are typically constructed for heavy-duty purposes such as industrial and commercial floors, driveways and parking spaces, hardstand areas and cold room floors. We investigate the advantages and qualities of industrial concrete floors plus offer advice on how to build it sustainably and economically.

Top advantages of industrial concrete floors
As industrial concrete floors are high-performance floors, it poses a multitude of advantages for high performing commercial and industrial spaces:

Improved abrasion resistance, dimensional stability and ability of load transfer at saw cut joints. Decreased potential for plastic and drying shrinkage cracking. Lower risk of curling.
Most importantly, it requires lower maintenance costs in the long run

Minimum requirements of industrial floor concrete
Point of departure for building industrial floors is to use concrete that is specifically designed and manufactured for industrial purposes. It should also comply with the following minimum standards and requirements:
  • Cement grade: Use concrete that has a minimum grade of 30 MPa for light duty industrial and commercial applications where there is heavy hard rubber wheeled traffic. This will improve the abrasion resistance and impermeability when power trowelled.
  • Strength class: It is advisable to use a CEM I or CEM II cement with a minimum cement content of 310kg per m3 (Cubic Meter).
  • Micro fibres: The concrete should ideally have an addition of 600g to 900g polypropylene micro fibres per 1 m3. This will make a significant difference in the reduction of bleeding and potential of plastic shrinkage cracking. It will further contribute towards increased impermeability as well as enhanced impact and abrasion resistance.
  • Slump: The acceptable slump range for industrial floor concrete is between 50 to 100 mm with the aim to accomplish a target slump of 75 mm.
How to avoid typical issues with industrial concrete floors
Drying shrinkage is one of the major issues that affect the dimensional stability of concrete floors. The potential for drying shrinkage can be decreased by:
  • Reducing the cement paste/aggregate ratio by using the maximum aggregate size and content.
  • Using admixtures to reduce the water required for the mix even further.
Ideally, industrial concrete floors should achieve a drying shrinkage value of less than 0.05% - which equates to 0, 5 mm per 1 metre length.
Curling is another common problem. The potential for curling can be reduced substantially by taking the following factors into consideration:
  • Thicker slabs are less likely to lift than thin slabs
  • Panel sizes should not be greater than 30 times the slab thickness or 4,5 m Square, whichever is lesser
  • Decrease the slab surface to the ratio of its thickness, ideally within 4x4m
Also important is to isolate the slab from structures such as walls, columns and manholes to reduce the slab restraint and level of induced stress. This will minimise cracking. If possible, also reduce any or all sudden differences in thickness of a slab, as this can also cause cracks.

Always take an uncompromising approach to quality
Taking shortcuts or using inferior products to save, will result in higher maintenance costs in the long run. Opt for a proven product like the Sephaku 42,5R. Manufactured by Sephaku Cement, it is fully compliant with the SANS 50197-1 specifications, which are minimum requirements for industrial floor concrete. Click here for more information or expert advice.


Whether you’re a novice builder, DIY diva or construction engineer, knowing how to mix concrete is an important part of almost all building projects. Even if you don’t have a concrete mixer, the process of mixing concrete is fairly simple once you understand what materials you need and how to use them.


Different projects require different types of cement, depending on how it will be used and the level of strength needed. If you’re unsure which product is best for your project, any good hardware store will be able to advise you.


Along with cement, you’ll also need to purchase sand and stone. The quantities of each ingredient depend on whether you’d like to create high, medium, or low strength concrete; mortar; or dry, lean mixes for brick and block manufacture. This expression of the proportions of ingredients of a concrete mix is known as the mix design.


To start mixing your concrete, you’ll need the following:

  • Heavy duty wheelbarrow
  • Spade
  • Aggregates of choice for your concrete / mortar / plaster or screeding
  • Water


Use the spade to add the cement, sand and stone to the wheelbarrow according to the required mix design, then mix all the ingredients thoroughly, ensuring they are well combined. Although you still need to add water, it is a good idea to mix the dry ingredients first to ensure consistency.


The next step is adding water. Be sure to read the label on the cement bag to ensure you’re adding the correct amount of water, otherwise the integrity of your structure could be compromised. Too much water weakens the mix, and too little water will make the mix difficult to compact, vibrate and work with.

Measure and pour a small amount of water into the wheelbarrow. Don’t put too much in at once as you’ll need to monitor the consistency as you mix.

Add water gradually, as necessary, until the mixture is thick and wet, with uniform workability, consistency and colour.


If you need more than one or two wheelbarrows of concrete for your project, the consistency and uniformity of the mix may not be the same for each batch. Using a rented concrete mixer from the local hardware store will ensure that the volume of concrete mixed will have an even consistency.


Measuring the amount of water used in one batch helps you judge how much will be needed for the next batch. A consistent water / cement ratio is very important as it has a direct impact on the strength of the finished product.

Here are some other important guidelines:

  • Select your materials based on the cement strength or performance needed
  • Characterise the materials, e.g. fineness of sand, stone size
  • Proportion your materials
  • Make and assess a trial mix, if necessary
  • Specify mix proportions relative to the application
did you know?

A typical builder’s wheelbarrow has a volume of 65 litres (two 50kg bags of cement)!

As the key ingredient of concrete, cement is the most widely used building material in the world. What’s more is that as the world becomes more urbanised, we need to produce even more cement to support this development. But the cement production process can be very energy-intensive.

In fact, experts estimate that cement production accounts for about five percent of global greenhouse gases, which is why the Sephaku Cement adopts the latest cement production technology and continually looks to innovate and improve its cement production process.


Believe it or not, although cement is produced en-masse around the world, it is one of the most complex substances known in materials science. We still don’t quite understand the scientific details of what happens once water touches cement powder.

There is an entire team of interdisciplinary researchers from several MIT departments working specifically on concrete and infrastructure science, engineering, and economics. The MIT Concrete Sustainability Hub (CSHub) brings together leaders from academia, industry, and government to develop breakthroughs and innovation in cement production to create the product in a more sustainable way.

Paving the the way for sustainable production

The plants of Sephaku Cement are an example of an integrated clinker and cement producer that use the latest cement production technology equipment. With every plant designed to produce CO2 emissions of at least 15% lower than the industry standard, it aims to be the most carbon-efficient cement producer in Southern Africa. As a result the company does not emit more than 30mg per normal cubic metre.


The main ingredient of cement is clinker (lumps or nodules produced by fusing limestone and materials such as clay during the cement kiln stage), which has a significant carbon footprint as its creation requires high temperatures. Blending clinker with other less energy-intensive materials (such as by-products from the steel, energy and other industries) can also mean a significant saving on energy consumption and a reduced CO2 footprint

With a limestone open cast quarry and flagship integrated cement production plant in Lichtenberg, South Africa capable of producing up to 1.2 million tons of cement annually, Sephaku Cement is a leader in environmentally friendliness. Its operations incorporate modern advances such as vertical roller mills for raw mix, coal and cement grinding; with variable frequency drives that maximise product extension. As a result, electrical energy consumption per tonne of cement is an impressive 20% lower than the industry norm.


The type of cement used 2 000 years ago by ancient Roman engineers has proved inspirational to modern-day researchers. In those days, the key ingredient of cement was a type of volcanic ash called pozzolana. Pozzolana reacts with water to make cement, acting as a natural clinker.

An industrial version of pozzolana, fly ash (the fine particles filtered out of the combustion gases from coal-burning electricity plants) is now being converted into cement powder by modern cement manufacturers. Because the process doesn’t require heat, the carbon footprint of fly ash cement is significantly lower than clinker cement.

There are even more ways to make cement production more sustainable, such as:

  • Installing sophisticated emission-measuring equipment
  • Bag-house filters for cement kiln stacks
  • Lowering the roasting temperature at which cement is created, therefore burning less fuel
  • Energy efficient vertical roll mills for preparation of raw material and grinding of cement

While there is still much to learn in greening cement production there is more innovation taking place than is commonly thought. That’s important because the cleaner the world’s most fundamental building material is, the more responsible we are in protecting our natural inheritance.


A local commuter transport company given the tools they need to succeed

“With the steady income from Sephaku Cement, I was able to buy another vehicle.”

A real partnership, with real volumes and long-term commitment – this is how Sephaku Cement’s Enterprise Development Programme (EDP) makes emerging small, medium and micro enterprise (SMME) development a priority in local communities.

Believe it or not, although cement is produced en-masse around the world, it is one of the most complex substances known in materials science. We still don’t quite understand the scientific details of what happens once water touches cement powder.

As a successful, proudly South African company, Dangote Cement SA (Pty) Ltd T/A Sephaku Cement recognises its responsibility to aid job creation and small business development to uplift and develop the communities in which it operates. The EDP was born to address this need in a sensible and sustainable manner. One of the many emerging businesses supported by the EDP is Molefe & Sons Transport Services, owned and managed by Abram Molefe.

Molefe started working as a taxi driver in 1986, later buying his own taxi and starting his transport business, Molefe & Sons. His relationship with Sephaku Cement began in 2009, the clinker and cement producer’s early days, when investors were coming to the site to assess the potential of the new venture.

Pieter Fourie, the CEO of Sephaku Cement, contacted Molefe and asked him to transport a delegation of VIPs around the area for a site inspection. “That’s when the relationship started,” Molefe remembers. “Since then, they call on me to assist with all transport needs especially employee transportation.”

And Molefe is kept busy: “I work morning, afternoon and night, starting at 6am in the morning. My next round is at 3:30pm, transporting more employees to the Sephaku Cement plant, with another shuttle at 10.30pm. Then at midnight I fetch them.”

The healthy working relationship with Sephaku Cement’s EDP has allowed Molefe & Sons Transport Services to grow significantly since 2009. The business now has three vehicles – two 22-seaters and a smaller 13-seater vehicle.

Says Molefe: “With the steady income from Sephaku Cement, I was able to buy another vehicle. I needed financial assistance and the company helped me with a letter that I took to the bank to secure the loan. Because I have a business relationship valued at R78 000 with Sephaku Cement, I was able to secure a loan of R850 000. I was also able to do much-needed maintenance on the first vehicle I was using.”

Molefe & Sons Transport Services now employs five shift-working employees, and is also able to hire a vehicle out to Bodibeng Trading, another Sephaku EDP success story. This kind of business cooperation is exactly what the EDP strives for, creating a circle of businesses that can work together, which, in turn, increases the number of job opportunities that are being created in surrounding communities.

“If I was not working with Sephaku Cement, I wouldn’t be where I am presently. I’m happy to be doing what I am doing,” Molefe says. But his aspirations don’t end there: “I want to be healthy and financially secure when I retire. Before then, I’d like to grow my business further and get one or two trucks and enter the trucking business.”

With the help of Sephaku Cement’s management support and steady stream of business, Molefe & Sons Transport Services are well on their way on their journey to sustainable success.

Read how a local businessman grew his transport business from one taxi to a transport triumph with the help of Sephaku Cement’s EDP.