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Sephaku Cement explains the ddifferences between drying and curing and the various phases that concrete sealers go through as they set.

Understanding the differences between drying and curing and the various drying phases that concrete sealers go through as they set can be intricate. While sealers and coatings typically follow the same setting process, some dry while others cure. To follow, we note the differences between concrete sealants that dry and concrete floor sealers that cure and what this means for the application of polyurethane sealants to stained concrete flooring.

To begin, let’s make sure we understand what it means when a sealant cures and how this is different to an application that dries. In the concrete industry we understand that curing is the process by which materials undergo hardening by way of a chemical reaction when various compounds are mixed. Much the same as the chemical reaction that cement undergoes when hydrating, two part sealants will also undergo a hardening phase when different parts of the 2 part sealants mix, this can also be referred to as a catalysed system.

So now that we understand the fundamentals of curing, let’s explore the differences between sealants that dry versus those that cure.

All sealants and concrete coatings contain liquid solvents which are known as carriers. Depending on the type and the volume of solvents present in the concrete coating will determine how the sealant will dry (or cure).

One-part Concrete Sealers One part sealants dry without curing whereby the solvent or liquid carrier evaporates as it becomes exposed to air, which in turn causes the resin or solid compounds of the sealant to dry creating a resin-like membrane on top of the concrete floor.

Two-part Concrete Floor Sealants Two-part sealants or catalyzed systems cure as they dry. When the two parts of the sealant mix, crosslinking occurs which forms a type of bonding that takes place during this chemical process. The bonding results in greater durability which in turn results in the coating being classed as a more high performance application, typically used on high traffic zones and hardworking floors.

While each concrete sealant offers various pros and cons each suited to different uses and needs, each coating follows very similar set of phases when drying, these include:

  • Shelf Life – This is pre-application where the concrete sealant is stored in an airtight container usually for no longer than a period of 1 year before sealant compounds become compromised. It’s important to note that two-part sealants tend to be more sensitive to a lengthy shelf-life and the appropriate storage needs to be adhered to. Every manufacturer can determine a different shelf life for their products, these guidelines must however be followed by the consumer/client.
  • Working Life – also referred to as “pot life” is when the sealant is in the application process. Affected by the environment and conditions under which the coating is applied (hot, cold, moist, dry, windy conditions), warmer conditions speed up drying and curing as well as shorten the shelf life of the product once it has been exposed to air and heat.
  • Open Time – Exposed to air after the initial application this drying phase is hugely affected by exposure to various conditions, depending on the chemistry of the sealant, open time can vary between 15 minutes and a number of hours.
  • Tacky – as the name suggests the tacky phase during the drying and curing of decorative cement sealants is when the coating film is tacky to the touch. While this may be so, it is important not to touch the surface of the sealant as finger marks and blemishes will remain as the coating continues to dry. It is critical that two-part sealants dry beyond this phase before re-applying a second coat to avoid the risk of trapping solvent that is still evaporating.
  • Tack Free - considered the final phase in the drying and curing process, the tack free phase has taken place when the cement sealant is no longer tacky to the touch, it is not that two-part coatings will be re-applied during the recoat window. Allow a period after this final phase before use, to ensure longevity of your chosen floor coating.

Sephaku Cement discusses safety considerations when building a “do it yourself” concrete fire pit and what you need to know to make it a concrete fire pit a “roaring” success.

Not only functional but a gorgeous feature, highlighting the aesthetics of any yard, we discuss safety considerations when building a “do it yourself” concrete fire pit and what you need to know to make it a “roaring” success. Of utmost importance is the choice of shape, size, location and design of your fire pit, below, find five safety considerations that should never be ignored when building a DIY fire pit:

  1. When selecting materials to build a do it yourself fire pit, never neglect to make use of fire safe materials. This is one area where cutting costs should never be pursued, paying critical attention to make use of the finest quality, fire primed materials. From selecting fire ready concrete blocks and bowls, to making use of fire bricks and fire clay mortar to line the fire pit with so that the necessary insulation is provided, ensuring that it is capable of withstanding extreme temperatures is a critical attention to detail when building your own fire pit.

  2. Another safety consideration to apply to your DIY cement fire pit is to be certain of the appropriate placement of the pit, clearance around the circumference and how safely one can pass by. While a concrete fire pit adds value and aesthetics of a patio or pool deck, fire is a dangerous element that can cause serious injury and significant damage to property if the placement is not well thought through. A safe distance from surrounding buildings and roofing as well as a safe clearance to move around the pit is a conscious consideration to make to be sure the outdoor fire pit is well positioned in relation to the area that you are building in.

  3. Consider the clearance between the rim of the bowl and the flames, making sure the flame area doesn’t overhang the border of the rim. Depending on the design of the pit and if the pit has an overhanging lip or border, leave ample space between the flame and border for those sitting or standing close to the fire pit. Once again, fire is considered hazardous and the utmost safety should be adhered to when adding this as a feature to outdoor entertainment areas.

  4. To ensure that the appropriate safety regulations have been adhered to, we recommend that burners are purchased pre-assembled by the manufacturer, keeping in mind that assembly needs to account for the potential of water entering the manifold, while at the same time ensuring even flame distribution, burner installations are placed in an upward position but must allow for water to drain from the tubing should the tubing get wet from rain or condensation. Purchasing your DIY fire pit burner from an accredited manufacturer you can be guaranteed that the appropriate functioning and safety installations have been professionally adhered to.

  5. While selecting a manual or automated control system is made based on preference, manual operation allows for users to take into account environmental factors that automated system cannot. When lighting a fire system manually, the height of the flames can be controlled, while wind factors and the intensity can be considered too. To prevent flames from blowing beyond the rim of the pit, more low set flames can be light and for fire pits that are further away from surrounding guests, higher flames can be set. While automated options offer their own set of pros and cons, when making safety considerations, manual controls allow the operator to appropriately adjust the flame height catering to various entertainment factors.

While basic guidelines will make this DIY job simple enough for even amateur builders to construct, safety guidelines and protocols should always be adhered to not only during the construction phase but during the operation of your cement fire pit ensuring that future use of a concrete fire pit is as safe and secure as possible. The design and layout of a wood burning fire pit could be quite different from gas burning fire pits.

Learn the differences between concrete dyes versus concrete stains and how to tell them apart.

Fairly new to the decorative concrete industry, concrete dyes are currently all the rage, replacing the previously popular concrete staining fad, below we describe the differences between concrete dyes and concrete stains and how to tell them apart.

Concrete staining is a chemical process, whereby the staining agent reacts with the calcium hydroxide present in concrete, but when making use of a concrete dye, the process is rather that of pigmentation; a non-reactive method where colour is mixed with concrete and penetrates the cement particles.

To follow, let’s explore each process in more detail, helping to highlight the differences between these two approaches to colouring concrete.

The Process of using a Concrete Dye As discussed the process of using a colour dye is a non-reactive one whereby colour pigment particles mix with the cement particles. Smaller in size, dye pigment particles are able to penetrate cementitious surfaces, allowing for more intense colour saturation while leaving minimal residue to clean up on the surface of the concrete after the effect has been applied. Available as a water or solvent based formula, concrete dyes can produce a monotone to translucent finish depending on the formula selected to be applied.

Designed to resemble marble, similar to the effect resulting from chemical stains, water based dyes produce a more translucent and uneven effect whereas solvent based dyes create a more solid and uniform colour finish. Other more unique effects may be accomplished by mixing water and solvent based dyes together producing a distinctive blend of colour.

An important note to remember when making use of concrete dyes is that given the rate at which pigment particles in concrete dye are able to penetrate porous cement particles means that even the smallest mishap during the application process can result in an undesirable finish. Another note to be aware of is that concrete dyes are not UV stable making them only suitable for indoor concrete flooring and not concrete flooring surfaces that are exposed to harsh sunlight and any adverse weather conditions throughout the day.

Concrete colour dyes are also available in an extensive colour palette, offering vibrant colour finishes and intensities. Although new to the concrete flooring industry, making use of concrete dye technology creates unique and diverse colour techniques for a striking and distinctive look to decorative cement.

Understanding Concrete Stains Concrete staining can be an intricate process given its translucent and marbled effect. Acid or water based concrete staining is available in a gorgeous variety of colours with end results that guarantee a unique finish well suited to both interior and exterior surfaces. Using a stain to colour concrete is the more popular method to creating a decorative look offering the ability to achieve almost any accent to concrete flooring.

By penetrating the concrete, cement staining agents have a chemical response when coming into contact with the calcium hydroxide present in the concrete mix. This process results in a unique mottling effect that resembles finishes similar to that of marble or granite. Although available in a variety of colours, acid stain tones are typically limited to earthy tans, browns, terracotta and the most exotic or the range, opaque blues and greens. Water based stains are available in a more extravagant colour palette broadening colour options and even allowing colour mixing, two tone blending, the layering of stains or perhaps even the inclusion of stencil decals where desired.

Regardless of the method used to colour decorative concrete flooring, the pigmentation process to adding accents to concrete is both affordable and accessible offering a variety of finishes, intensities, colours hues and effects.

Available in a variety of patterns and colours, stamped concrete floors create a picturesque finish to create gorgeous concrete flooring options.

Together, lets discover the process of creating these decorative finishes and uncover a world of stamped concrete floors and the number of patterns, designs and colours that this flooring option is available in.

Given the number of technological advancements the concrete industry has made over the last decade; concrete floors are available in an almost limitless variety of colours, shapes and textures, what’s more is concrete flooring is available at an affordable cost, making this flooring type a highly desirable and accessible option even for the most rigid budget.

Selecting Stamped Concrete Patterns

Patterned stamped concrete can be created to resemble a variety of finishes based on your desired end result. Ranging from brick to flagstone, cobbled or slate, with natural textures to more structured and modern finishes, stamped concrete floors can create the ideal look to compliment your home, the range of textures and colours is only limited by your imagination.

Stamped Concrete Patterns and Designs Include:

  • Random Interlocking Square Cobble Stone with Rounded Corners
  • Random Interlocking Fractured Slate Cobbles with Square Corners
  • Large Earth Surface Embossing Skins
  • River Stone Skins for Large Surface Areas
  • Uniform Rectangular Ashlar Stone
  • Uniform Sleeper Wood Planking
  • Uniform Pine Wood Planking
  • Natural Garden Rock Finishes
  • Uniform Small Cobblestone
  • Small Lime Stone Squares in a European Fan

Applying Colour Variants to stamped Concrete Floors.

Once the base set up for installing concrete floors has been followed the process of adding a colour variant to concrete floors can occur via two junctures:

The first and least common process sees colour options added to the cement mixer creating a solid colour throughout the concrete. The alternate option is to dry-shake a colour hardener onto the surface of the cement which is then gently worked into the concrete. The colour/hardener dusting process is applied to the concrete a number of times over ensuring that the concrete is pigmented a few inches deep should the set surface chip or scratch throughout its life time.

Colour variants include:
  • Buff
  • Walnut
  • Mahogany
  • Grey and Slate Variants
  • Pinks and Salmon
  • Tan Variants
  • Slate Grey
  • Brick Red or Terracotta
  • Sand and Stone Options

by mixing colour tints with each other, the end results create a one of a kind look that can be perfectly matched to paint variants or to create a never seen before finish, should you wish to create a unique colour blend.

The Process of Stamping Concrete Patterns

Once the concrete has been effectively coloured with the desired end result, the stamping process can commence. An uncomplicated process at best; by simply placing a series of stamping tools reflecting the selected pattern onto the concrete, stamped concrete patterns are carefully pressed into the coloured concrete. Various patterns, textures and finishes may be achieved, depending on the desired design selected.

After curing for 24 hours, the pressed concrete slab is power-washed to ensure excess colour hardener is removed, keep wet and warm for a few days to facilitate curing followed by the process of acid-etching a few days later. A sealant is later applied and for outdoor surfaces a sandy sealer can be used to preserve the surface of the stamped concrete slab and add traction or grip to potentially slippery areas.

With a world of stamped concrete flooring now at your fingertips, we hope to have helped to explain the process of creating beautiful stamped concrete flooring and the various finishes that can be accomplished based on your desired end results. Happy stamping!

To stain or to paint? That is the question. We’ve listed the differences between concrete paint and concrete stain so you can decide for yourself which one is best for your specific project.

You’ve finished renovating or upgrading your home, office or driveway and your concrete floor is looking great. Now you just have to decide how you are going to beautify your floor with one of the above-mentioned concrete floor finishes. Let’s have a look at the pros and cons and what applications the paint or stain finishes are best used for.

Concrete paint

Paint is slightly thicker than stains and covers the top of the concrete. Paints can even help protect the surface of the concrete as it creates a layer on top of the concrete. Concrete paint can be used for indoor and outdoor spaces and is brushed and rolled onto the surface. Let’s have a look at some of the pros and cons of concrete paint.


  • Elastomeric paints cover and protect the surface while keeping it from drawing in moisture.
  • There are epoxy concrete flooring products available that do not require sealing or priming the floor before application and are great for areas with heavy traffic.
  • Paints do not require a sealant or coating. There are many colour options with paints and the colours are uniform.

  • If applied incorrectly, the paint can chip or peel. They can also crack over time.
  • Paint requires a lot of preparation before it can be applied – cleaning, degreasing and acid etc.
  • Paint is more expensive than stains.
  • Paint is difficult to apply and recoat – you need a professional to apply it.
  • Maintenance is difficult and can be expensive.

What is concrete paint best used for?
Concrete paints can be used as a decorative option but are better for spaces where the concrete needs sealing and protection such as a driveway, basement or garage. However, paints can be used for indoor and outdoor spaces to spruce up concrete flooring.

  • Stains go on quicker, dry faster and are less work than paint.
  • They are a quick and easy décor option.
  • Stains do not crack, chip or peel.
  • You can create unique looks with stains that are impossible to achieve with paint.
  • Stains are less expensive than paint.
  • They are easy to apply and can be recoated very easily.

  • Cons
    • They offer no protection for the concrete flooring.
    • Acid-based stains can be complicated to apply and offer limited colour options.
    • Water-based stains can require more than one application to deepen the colour.
    • Stains can fade over time if they are not sealed.
    • The colour options are limited, and there is no colour uniformity.
    • Water-based stains usually require a sealant to prevent fading.

    What is concrete stain best used for?
    Stains are best for colouring concrete flooring as a décor option, but should not be used in areas with heavy traffic where the concrete can be damaged. Patios or low traffic indoor areas are good examples of where concrete stains will work best.

    How will you decide between these two finishes? We conclude that you will know which finish to use when you know what the purpose of your project is.

    Whether you are looking to stain or paint your concrete or cement floor, contact Sephaku Cement for advice, great cement floor products and excellent service. We will assist you so your flooring will look dashing in no time!

    Did you know that cement can absorb moisture from the atmosphere if stored incorrectly? This can affect the quality and the strength of the cement. So, here are some great cement tips and tricks on how to store cement bags on site.

    • When storing cement bags, it is important to keep it in a building or structure that is dry (and leak-proof and moisture-proof if possible).
    • When stacking cement bags, keep the bags off the floor. A good solution is to stack them on pallets or wooden planks (about 15-20cm off the floor). Adding a plastic sheet underneath the pallets or planks will also help to keep moisture out.
    • Another tip for the storage and handling of cement is to keep the cement bags away from any exterior walls (at least 60cm all-round).
    • Another tip for stacking cement bags is to stack them as close to each other as possible. This reduces the amount of air flowing around the bags and reduces the chance of the bags absorbing any moisture.
    • It is best to keep the width of the stack to about 3m (or the length of four bags) and the height to no more than 10 bags when storing cement bags. Also, keep in mind that the cement bags should be packed alternately length-wise and cross-wise. This prevents the stacks from falling over.
    • You will also increase the lifetime of cement if you stack the cement bags in such a way that you can remove and use them in the order they were received (FIFO – First In First Out) (cement normally starts deteriorating after about three months inland and one month at the coast). You could also stick labels on the stacks to keep track of when the cement was purchased.
    • Another great tip on how to store cement bags on site is to keep different types and strengths of cement separate. For example, don’t stack 32,5R and 42,5R together. This way it will also be easier to keep track of your inventory.
    • If you absolutely have to store cement for long periods of time, it is always a good idea to cover the stack in a water-proof layer such as plastic or tarp as cement is hygroscopic, meaning it will absorb moisture from the air.
    • When handling cement bags, ensure that you follow the following cement tips and tricks:
      • Always move cement by two persons and not one at a time and when lifting use your legs(knees) and not your back)
        • Don’t drop the bags as this can damage and weaken the packaging
        • Roll the bags over before lifting them as this loosens the cement and will prevent the bags from splitting open
        • Carry the bags by supporting the underside and they will not sag in the middle and split
        • Store the bags flat with the broad side down, never upright or on the sides.
      • When storing cement bags, it is important to remove any sharp objects and any foreign substances like foods or other chemicals as this affects the quality of the cement.

    Sephaku Cement aims to give our customers the best value and great advice. Contact Sephaku Cement today for all your cement and concrete products or click here to locate a Sephaku Cement retailer near you.


    Sometimes, all it takes to enter a building is simply lifting a door handle. If you don’t attempt to open the door, how are you going to get in? There is a lot of emphasis on the use and effectiveness of outdoor concrete walls, but we tend to forget about the indoors. Come in and join us as we explore the beauty of indoor concrete walls in its different forms.

    For many years, interior designers and architects have been trying to add sizzle to their clients’ home improvements by adding concrete walls and concrete wall finishes. Beautiful corporate buildings are following these trends and hospitals are winning their patients’ hearts before they even consult with the doctors while waiting in rooms with beautifully designed concrete slabs.

    Millennial generations are also shifting things around and breaking the old traditional way of doing things. They invest in properties such as studios, penthouses and loft apartments with unique decorative accessories that bring out the beautiful rough walls with a touch of glass and slab ceilings.

    Concrete walls are economical, environmentally friendly and durable, consequently, they have been deliberately manufactured to have a longer lifespan. However, due to concrete’s high absorbency rate of water in places like the bathroom and kitchen, extra maintenance is necessary due to the high concentration of moisture from the steam. Different types of coatings can be used to protect the walls and avoid rotting and decay. Although concrete paint is a partial solution to the problem, it must be applied correctly and according to the suppliers recommendations, because it is different to normal wall paint, the absorption rate is high and takes quite some time to dry.

    Here are five steps to paint concrete walls if you are planning on doing it yourself:
    First time painting of a wall

    1. Make sure the concrete is free of dirt and grime:
      • Use a pre-paint cleaner and a pressure washer to remove roots from the wall.
      • Concrete walls should only be painted once fully cured and dry.
    2. Peel off old paint:
      • Some elbow grease and a wire brush may be required to clean the peel offs.
    3. Seal the surface of the concrete walls:
      • Prevent water from entering the inside of the walls and avoid mould and moisture by covering the concrete with a sealant.
    4. Prepare the concrete:
      • Pre-coat it with a bonding primer (water-based primer to create a uniform topcoat finish and a stronger adhesion between the coating and surface). Wait for about eight hours before painting.
    5. Paint the concrete:
      • Masonry paint is the best for concrete wall painting due to its quality. Wait at least a day to let each coat dry and do about two to three coats. Also note, if misapplied/incorrectly applied, concrete paint can chip or crack.

    Concrete stain is another simple, yet elegant, acid-based chemical and water-based acrylic technique to play around with. There is a chemical reaction where the hydrated lime in the concrete reacts to the acid in the concrete stain on the surface. Take note:- the minute the staining process is completed, it cannot be reversed. The art of acid-etch staining creates natural earthy shades of brown and hues of blue/green.

    To add an attractive, modern look and the desired ambience to a concrete wall calls for a trendy finish. CemWash is a versatile and easy to use waterproof cement finish consisting of Portland cement. It comes in a powder form which you can be mixed with CemBond, a liquid that when mixed with water creates the right consistency for the first coating.

    Contact Sephaku Cement today to find out more about indoor concrete walls, concrete wall finishes, concrete stains and concrete paints. We would love to help you discover the beauty of indoor concrete walls.

    Portland cement is well-known and most widely used in the construction industry but how is it made? It was developed from natural cement made in Britain from the middle of the 18th century. Its name is derived from its similarity to Portland stone, a type of building stone quarried on the Isle of Portland in Dorset, England.
    The development of modern Portland cement began in 1756 when John Smeaton experimented with combinations of different limestones and additives relating to the construction of a lighthouse known as Smeaton's Tower.
    Most people are aware of and familiar with the normal, grey cement known as Portland cement and below is the process of making the most common type of cement used today.
    Firstly, to make Portland cement, you need to mine or extract the raw materials from the quarry:

    • Limestone
    • Argillaceous shales (shales are a fine, clastic sedimentary rock made up of a mix of clay minerals and other minerals such as quartz. Argillaceous minerals mean the minerals contain substantial amounts of clay-like components and may appear silver)
    • Chalk
    • Schists (schists are coarse, metamorphic rock made up of layers of minerals and can easily be split into sheets or flakes)
    • Shells
    • Clay
    • Calcareous nodules (calcareous means a component containing lime or being chalk-like and calcareous nodules are small, irregular lumps made up of calcium carbonate)
    • Iron-bearing aluminium-silicates (A chemical compound made up of aluminium, silicon and oxygen found in certain minerals)
    The main raw materials are usually mined on site and the other minor raw materials can be brought in from other quarries. Mining limestone requires drilling and blasting techniques, but technology ensures that vibration, dust and noise are kept low.

    Depending on the size of the mined raw materials, they might be crushed before being stored until they are required.

    The next step is to crush these raw materials into a very fine powder. This is then blended in the correct proportions. This mix is called the kiln feed as it is sent to be heated in a rotary kiln. The kiln reaches temperatures up to about 1 500˚C.

    The rotary kiln is a tube (which can be up to 200m long and 6m in diameter) with a flame at the end. The kiln feed enters the rotary kiln from the cool side and moves towards the end with the flame. At the end of the kiln, the feed falls out and cools down again.

    The kiln creates the material known as clinker. The intense heat causes chemical and physical reactions that melt the kiln feed into clinker. The clinker is usually rounded nodules between 1mm and 25mm across.

    Next, the clinker is cooled with air and the coolers create clinker minerals which define the performance of the cement. After it has cooled, the clinker can be stored in a clinker store, or it can move on to the cement mill.

    At the cement mill, the cooled clinker is ground into a fine powder to become Portland Cement. Small amounts of gypsum (a type of calcium sulphate) are also usually ground up with the clinker. This helps to control the setting properties of the cement when mixed with water.

    Finally, the cement is checked to ensure it meets the standard and is stored in silos. It is then sent to be packed in bags.

    Sephaku Cement has two cement plants namely, Aganang in Lichtenburg, Delmas milling plant in Mpumalanga, as well as a fly ash plant in Kendal.

    Contact Sephaku Cement to learn more about our production of Portland cement, the different types of cement as well as our concrete and mortar options. Sephaku Cement wants to help you build strong with excellent quality products.

    While mixing concrete may come off as being somewhat of a no brainer, find top tips and the best kept secrets on how to hand mix concrete to from the strongest and most durable concrete. Mixing concrete can’t be classed as simply adding water to a Portland cement and aggregate mix and hoping for the best. There are a number of factors to consider.

    The Secret to Mixing Sephaku Cement

    • Always wear gloves, protective eyewear and old clothing - Cement is exothermic which means that there is a chemical reaction during the hydration of cement. This can also be referred to as “heat of hydration”. Although extreme heat is usually only attributed to large volumes of cement paste, always be aware of this chemical response when mixing concrete and that if splashed onto the skin, cement paste may burn.
    • Measure your mixture – A number one tip when mixing concrete and preparing the most durable concrete, always measure the amount of water used to mix with the concrete. Too much and too little water can affect the strength of the concrete where, too little water will result in a crumbly effect and too much water will cause set concrete to be weak.
    • Mix well – The best was to mix concrete is to replace a standard shovel mix with a metal rake for speedier and more effective results. Creating a similar action to that of a fork or balloon whisk (in cooking) the prongs of a metal rake agitate the mixture more effectively, combining the ingredients faster, reducing the amount of time and effort needed to create a smooth, tacky cement paste.
    • Combine (dry to wet) water and concrete slowly so that the paste gradually thickens without creating lumps and dry pocket clumps of cement paste that is difficult to combine. The goal here is to create a consistent mixture of water to concrete that’s mixed well and easy to place.
    When Concrete Paste is Too Runny.
    Although runny concrete will (eventually) set, the concrete will be frail and weak, vulnerable to cracks and fractures. You will know your mixture is too runny because the combined cement will have no traction or grip and will sag or slump when dug into a trough. Avoid runny and thin concrete paste by measuring the water in a bucket before mixing, instead of measuring by eye with a hose. Keep in mind that as the water is absorbed the paste can become "soupy" if not mixed properly so be sure to mix well, combining the paste well before adding more water or dry cement. You may like to set a few handfuls of dry cement aside for later, should your cement paste mixture become too runny, using this to thicken the mix up if necessary.

    How to Resolve Crumbly or Dry Cement Paste.
    Concrete is too dry if the mixture crumbles and clumps resulting in an inconsistent mixture. In order to resolve concrete mix that is too dry, create a well in the centre of the heap, adding one measure of water at a time. Be certain to mix well after each cup in order to review the results before adding excess water, wetting the concrete mix too much. Once the concrete mixture is thoroughly wetted, again create a well where the sides of an ideal concrete mix will remain in place without crumbling (or slosh because it’s too wet) and where the surface is slightly shiny.

    We highlight the few common types of concrete cracks and other blemishes that occur most frequently and investigate its typical causes.

    The main classification of concrete cracks
    All concrete cracks can broadly be classified as either dormant or active. The difference can be summarised as follows:

    • Dormant cracks remain unchanged; and
    • Active cracks change over time, in direction, width or depth.
    Cracks can be diagonal, longitudinal, vertical or random and the severity of a crack is also characterized by its direction, depth, width. Both dormant and active cracks create opportunities for moisture and other deleterious materials or liquids to penetrate and can lead to future damage if left unrepaired.
    Types of concrete cracks and its causes
    Some of the concrete cracks that are seen most often include:
    • Plastic shrinkage cracks: If it occurs, it will normally be visible shortly after placing the concrete. The shrinkage is caused by the forces and subsequent stresses that are created by the rapid removal of water from the concrete. Consequently the severity of cracking is largely influenced by the rate of drying of the concrete surface. The drying and removal of water from the surface depends on such factors as : -
      The temperature of the air and the concrete.
      • The relative humidity of the atmosphere.
      • The velocity of the wind.
      • The absorbency of the surface in contact with the fresh concrete.
    • Crazing, also known as checking or map cracks: This is a network of fine, superficial cracks that feature across the surface of the concrete. Craze cracking is usually caused by excessive floating and trowelling of the wet concrete surface or by applying driers comprising neat cement or a dry mixture of sand and cement onto the wet surface and then trowelling. This surface bear bad wear resistance and has a tendency to delaminate easy.
    • D-cracks: D-cracks run deeper than surface cracks and either originates from a concrete joint or runs parallel to it. It is caused by moisture penetration at the joints.
    • Hairline cracks: Hairline cracks are very thin, but run deep and could sometimes be a bit wider at the top than at the bottom. These cracks typically occur as the concrete settles during curing. It is also known as plastic settlement cracks.
    • Pop-outs: These are conical, slightly sunken depressions that appear on the concrete surface. It commonly appears due to pieces of aggregate close to the surface of the concrete that are highly absorptive, such as clinker ash with sometimes high free lime present. As a result, it expands and protrudes through the surface.
    • Scaling: Scaling causes minor pock-like marks on the concrete surface and exposes the aggregate underneath it.
    Scaling can be caused by different issues. Firstly, it appears when concrete is not adequately finished and causes moisture to infiltrate. The moisture expands when there are temperature changes and pushes off pieces of concrete from the surface.

    Then there is delamination. Ineffective finishing methods and too early floating before all or most of the bleed water has evaporated can lead to excessive moisture or air in the concrete, which will in turn rise to the top and form pockets just below the surface. These pockets may create blisters, which can break open and cause scaling.
    • Spalling: Spalling is similar to scaling, but the surface depressions are larger and deeper and often linear to the length of a rebar (the reinforced steel rod used in concrete).
    There are multiple issues that can lead to spalling. This includes pressure from under the surface of the concrete, inadequately constructed joints or decomposition of the rebar in the concrete.
    • Offset cracks: Offset cracks occur where the concrete on the one side of the crack is of a different height than on the other side of it. It generally arises when the surface under the concrete has not been levelled or inadequately/ inconsistently compacted.
    • Diagonal corner cracks: These cracks run diagonally from one joint to its vertical joint at the other corner of the concrete slab. It appears because of curling or warping. Curled up or warped corners are not very stable as it generally has empty spaces below it. As a result, it often cracks after curing, the moment weight is applied.

    Prevention is better than cure
    When analysing the causes of cracking, it becomes clear that prevention is better than cure. Be sure to avoid errors in design and detailing and apply sound construction practices right from the word go. Feel free to get in touch with Sephaku Cement for expert advice on construction of concrete fixtures.

    We delve into concrete curing and the most suitable curing techniques. Curing is a process that is executed immediately after the placement and finishing of the concrete, to ensure that all the ingredients bond fully. This is done by retaining suitable moisture and temperature conditions. Adequately cured concrete will demonstrate the following characteristics:

    • Improved strength
    • Enhanced volume stability
    • Reduced likelihood of cracking
    • Resistance to freezing and thawing
    • Resistance to wear and abrasion, such as dusting, crazing and scaling
    Ultimately, concrete structures that have been properly cured will be more durable in the long term.

    The two curing categories
    Curing techniques can generally be divided into two groups:
    • Those that add moisture
    • Those that prevent moisture loss
    Each of these methods has advantages and disadvantages that need to be considered before deciding which one is most suitable.

    Curing techniques that add moisture
    The typical curing methods that add moisture are:
    • Sprinkling: This simply involves the continuous sprinkling of the concrete with water at intervals.
    • Wet covers: In this technique, the concrete is covered with damp, moisture-retaining materials such as straw, cotton mats or burlap, which is a coarse, hemp-like fibre. Some also use moist earth, but it can be quite messy.
    • Ponding: This is done by forming a little wall around the concrete slab normally using sand and by flooding the concrete surface with water.
    Both sprinkling and use of wet covers are excellent curing techniques as it also provides cooling through evaporation, which is especially critical in hot weather. When sprinkling, it is just important to keep the intervals frequent enough - so that they concrete will not dry out in between. When using wet covers, it is important to place them as soon as the concrete hardens. Curing techniques that prevent moisture loss
    The most common curing method to prevent moisture loss is to seal the surface through the use of the following types of material:
    • Plastic sheets: Waterproof plastic film is a lightweight barrier that is easy to apply, regardless of the shape and size of the concrete surface.
    • Waterproof paper: The surface needs to be wet with fine water spray before the waterproof paper is placed.
      When using waterproof paper, it is imperative to check that it is thick enough, as too thin paper may discolour the hardened concrete

    An easy and inexpensive curing method
    Curing compounds are membrane-forming substances that are relatively inexpensive in comparison to other curing techniques. It can easily be applied with spray equipment such as hand-operated pressure sprayers. It also allows for long periods of curing even while the concrete is in use. Here are some useful pointers:
    • In the case of heavy rains within a few hours of application, the compound must be reapplied.
    • Brushes can also be used, but only on formed surfaces; as it could mar smooth surfaces.
    • They are also available with dyes in order to see which areas are sprayed and which areas were missed. (The dyes normally degrade after a while and present no discolouration issues).

    Adequate curing length
    There are several factors that can influence or determine the concrete curing period:
    • Ratio of concrete mixture;
    • The level of strength required;
    • The size and shape of the concrete structure;
    • Weather conditions; and
    • Future conditions that the concrete will be exposed to.
    To determine a suitable length for curing, it is therefore best to consult specialists first. For expert advice on curing techniques, feel free to get in touch with Sephaku Cement.

    Building experts agree that for masonry homes and offices, concrete stairs are more stable and durable than wooden stairs. Here is the lowdown on building concrete stairs.

    It starts with a solid design
    Concrete stairs need to meet the following requirements:

    • Comply with prescribed building codes and standards;
    • At least 90cm wide to allow sufficient space for use;
    • It must provide rails;
    • An angle and slope that facilitate comfortable use, even by older people; and
    • A solid foundation.
    Considering the complexities of such a structure, it is best to commission a civil engineer to conduct the design.

    Start by building the form according to the design
    You will start by building your formwork according to the specifications of the design. Here are some pointers:


    You can use low-grade plywood such as 2x100mm or 2x180mm to create your formwork, but it is critical to check that it is of sufficient thickness to support the weight of the concrete you are going to pour.

    • Cut all the forms for the framework;
    • First lay the side forms to create a 2-dimensional side elevation of the stairs.


    Ideally, the formwork of the concrete stairs should be fastened to both the foundation and the ceiling of the building. For this reason, it is recommended that the ceiling slab and stairs are poured on the same day.

    • Use screws to fasten the formwork firmly to the foundation and ceiling slab of the building;
    • Check that the steps will bond to the foundation in a seamless connection.
    Utilise wooden rods to create braces to resist the outward thrust of the poured concrete. Then nail a sufficient number of rods all along the outer surface of the form.


    The final step of the formwork is to lay the riser faces.

    • Add braces to the centre for stability;
    • Ensure that there are no gaps between the boards;
    • Use a spirit level to straighten the forms and level the treads.
    Ultimately it is important that the entire framework is locked together tightly and securely.


    To design the correct concrete mix, you may contact Sephaku Technical Sales for advice on mix design/proportions needed.

    One of the most critical parts of creating concrete steps that will last; is using the correct concrete mix. For this type of application, a high strength concrete mix will suffice. For an area of 5 square metres, you will need:

    • 2 x 50kg bags of Sephaku 42,5N blended cement
    • 2 x 65-litre wheelbarrows of fine sand
    • 2 x wheelbarrows of gravel
    • Water
    Mix thoroughly, using enough water to create a mixture that is easily pourable.

    • Start at the bottom and work your way up
    • Pour only one step at a time
    • Spade/vibrate the mix to remove any entrapped air
    • Spread the concrete evenly and smooth the surface finish to the desired texture

    • Level the steps with a screed board or wooden float
    • For a finer finish, use a hand / steel trowel

    To avoid cracking, you should allow for a curing period of at least two weeks. Click here for best practices on curing techniques (link to our blog article about curing techniques). As soon as the concrete has set, the form boards can be removed with a hammer and crowbar. Just be sure to exercise patience to avoid damaging the stairs’ edges in the process. The supporting formwork at the bottom of the stairs must stay in place until sufficient strength has been achieved, which will most likely be in around 28 days.

    To build structures that will last, you need the right type of cement. We take a look at the different types of cement and its applications.

    The three main strength classes of cement All cement is mainly classified into three strength classes.

    • 32,5
    • 42,5
    • 52,5
    This figure is typically accompanied by either an “N” or ”R”, which denotes the period of time it takes for the cement to reach the suitable strength.
    • The N implies that it will have normal strength gain; and
    • The R implies early/rapid strength gain.
    This is important to know, as should you for example build a structure that requires rapid setting and hardening, you would use an “R” type of cement that will in other words reach strength at an earlier age.

    Cement standards
    Questionable materials will produce questionable results. For the South African built environment, it is recommended to use cement that complies with the requirements of South African National Standards (SANS) 50197-1. All the Sephaku Cement products fully conform to the requirements of the strength classes as specified by SANS 50197-1, as well as the National Regulatory Of Compulsory Specifications (NRCS) requirements.

    General purpose cement that gains strength at an early stage
    The Sephaku 32 is a 32,5N general purpose blended cement that reaches strength at a normal age and that is suitable for general use in:
    • Concrete for home or building structures
    • Mortar, plaster and screed applications.

    Sephaku 32 applications
    The Sephaku 32 can be blended to achieve low, medium or high strength concrete for a myriad of applications:
    • High strength concrete: At the correct proportions columns, ground slabs and light -duty industrial floors;
    • Medium strength concrete: paths, driveways and light-duty floors;
    • Low strength concrete: foundations, domestic flooring, steps, paths and fencing;
    • General purpose mortar: bricklaying and plastering; and
    • Dry, lean mixes: brick- and block manufacturing.

    General purpose cement that has normal strength gain
    The Sephaku 42 blue is a highly versatile 42,5N general purpose blended cement that is suitable for a comprehensive repertoire of concrete, mortar and screed application. It can be blended to achieve all the required strengths of concrete for the same applications as the Sephaku 32 mentioned above.
    Sephaku 42 blue benefits
    • Suited for a comprehensive range of building and civil work;
    • Used to manufacture concrete products;
    • Appropriate for any domestic concrete use; and
    • It uses less water to achieve a mix that is cohesive and durable.

    Early strength cement for fast demoulding and striping of formwork
    The Sephaku 42 green is a 42,5R cement that develops strength at an early stage, which makes it most suitable for the following applications:
    • Any type of building and civil work;
    • Instances where fast demoulding, striking or striping of formwork is advantageous;
    • Ready-mix; and
    • Site-batched concrete, mortar and screeds.
    This cement also has a significantly reduced water demand which in turn leads to concrete that flows and pumps effortlessly and creates an improved surface finish with enhanced durability.

    High performance cement that requires day one strength
    The Sephaku 52 is a 52,5N high performance cement that is suitable for civil engineering and structural concrete applications that require day one strength and cold-weather concreting. This includes:
    • High-strength concrete, precasting and ready-mix;
    • Water-tight, structural and pre-stressed concretes; and
    • Precision grouts, repairs and formulated cement products.
    It is also ideal for use with cement extenders that enhance the concrete properties such as silica fume and fly ash or slagment.
    For a comprehensive guideline on the types of cement and its applications, as well as the mix proportions for the various concrete strengths, click here to download the Sephaku Cement product brochure now.

    Concrete is made up of four elements: cement, sand, stone (aggregate) and water. The cement: sand: stone ratio is critical as it determines the compressive strength of the concrete, which in turn establishes the capacity of the structure you build to withstand loads. We offer a guideline to solid concrete mixing proportions for optimal compressive strength.

    Choose the right cement for the right application

    Point of departure would be to select the right cement for the right application and to check that it complies with the relevant specifications to ensure a lasting end product. Click here for more information on the types of cement and its applications.

    Input equals output

    Apart from choosing the right type of cement for the right application, it is also critical to take an uncompromising approach to the quality of the cement you choose, to ensure structures that will last. The range of cement supplied by Sephaku Cement does not only meet, but also exceeds the relevant standards of the built environment in South Africa:

    • Manufactured according to the requirements of the National Regulator for Compulsory Standards;
    • Sold under a Letter of Authority (LOA);
    • Carry the SABS mark certification ; and
    • In accordance with the South African National Standards (SANS) 50197-1.

    Consult manufacturers’ guidelines for ideal mixing proportions
    As soon as you’ve selected the cement that is most suited to your application, you will need to consult the manufacturers’ guidelines to determine the ideal concrete mixing proportions. The mixing proportions are also subject to the strength of concrete you need, which can generally be classified in the following five groups:
    • High strength (25 - 30 MPa)
    • Medium strength (20 – 25 MPa)
    • Low strength (10 – 15 MPa)
    • Mortar (5 MPa)
    • Dry, lean mixes (7 – 14 MPa)

    Examples of concrete mixing ratios
    For the purposes of this illustration, we will take a look at the Sephaku 32, a 32,5N general purpose blended cement that reaches compressive strength at a normal rate and that is suitable for an extensive range of building applications, including general domestic or building concrete, mortar, plaster and screed.
    The guidelines allow for minimal wastage of between 5-10% and are based on a 65-litre builder’s wheelbarrow. Please note that one 65-litre wheelbarrow load of cement is equal to two 50kg bags in volume.
    • Dry, lean mixes for brick and block manufacturing: One wheelbarrow of cement (= 2 x 50kg pockets) and eight wheelbarrows of sand.
    • General purpose mortar for bricklaying and plastering: One wheelbarrow of cement and six wheelbarrows of sand.
    • Low strength concrete for foundations, domestic flooring, steps, paths and fencing: One wheelbarrow of cement, four wheelbarrows of sand and four wheelbarrows of stone.
    • Medium strength concrete for paths, driveways and light-duty floors: One wheelbarrow of cement, three wheelbarrows of sand and three wheelbarrows of stone.
    • High strength concrete for columns, slabs and heavy-duty industrial flooring: One wheelbarrow of cement, two wheelbarrows of sand and two wheelbarrows of stone.

    These concrete mixing proportions will vary, subject to the type of cement that is required. For a detailed guideline on concrete mixing proportions of 42, 5 and 52, 5 types of cement, click here to download the Sephaku Cement product brochure now.