How to expose aggregate on concrete floors

How to expose aggregate on concrete floors

Some concrete projects call for smooth gravel stones to be exposed for textural and decorative purposes. There are several ways of exposing aggregate on concrete floors. It all depends on the desired appearance and size of the project. Only the top of the stone is revealed, while the rest remains permanently embedded in the concrete. Usually, surface mortar is removed to a depth of no more than one-third of the diameter of the aggregate particle.

1. Brushing and washing

This method doesn’t require special tools or chemical retarders and is the oldest and simplest way of exposing aggregate on concrete surfaces. The thin layer of surface mortar covering the aggregate is simply washed away by spraying with water and scrubbing with a broom until the aggregate is exposed to the desired depth. 

The timing of doing this is very important. Begin as soon as the surface mortar can be removed without overexposing or dislodging the aggregate – the concrete will need to have started setting already, so wait an hour or so after pouring. You can do a test by lightly brushing the surface mortar away in a small area with a stiff-bristled broom.

2. Using a surface retarder

Most contractors use a chemical surface retarder to expose the aggregate. They do this by spraying the retarder onto the slab surface immediately after placing and finishing the concrete. Doing this delays the setting of the concrete and allows them to remove the cement paste a day or so later. This can be done by either pressure washing or scrubbing the concrete surface. Exposing the stones this way can be very useful when working in hot weather or working on large jobs such as pavements and long pathways.

3. Abrasive blasting

Abrasive blasting allows the aggregate to be exposed after the concrete has set and hardened. Either shot blasting or sandblasting can be used. A disadvantage of this method is that it can dull the aggregate’s appearance due to fracturing the surface of the smooth stones. If you want to preserve the shape and full color intensity of the aggregate, this is not the best method to use. 

These three methods of exposing aggregate on a concrete surface allow contractors to create textured and decorative structures. The most common application of this building method is on concrete pathways, parking lots and pavements where the stones give added grip and a pleasing look to the grey concrete.

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LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges. 

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LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in Mbeya, Southwest Tanzania.

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At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.

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How to minimise concrete wastage on-site

How to minimise concrete wastage on-site

In any construction project, there is likely to be concrete wastage – a small percentage of the concrete that gets dropped on the floor, left on the mixing bed or left unused. These small amounts of concrete wastage still add up to some loss in costs for the contractor, so they need to be minimised as much as possible.

Around three to five percent of concrete is usually wasted on an average building project. However, even this amount can increase the cost of the project. Proper planning and taking extra care when mixing and working with concrete are the best ways to reduce wastage on-site. However, there are several other steps that contractors can take to minimise concrete loss.

Pre-pour checks can minimise concrete wastage

Firstly, pre-pour concrete checks should be conducted to ensure that the site is prepared properly. There should be minimal travel distance between the site where concrete is mixed and where it will be poured. This will reduce the chances of spillage on the way to the pour site. 

Concrete pour cards should be completed as this will inform workers exactly how much concrete needs to be prepared for the job. These cards will ensure that no extra concrete is mixed, which will go to waste when it is not needed for the project. Contractors need to calculate the volume of concrete needed, as accurately as possible, before the pour takes place.

Steps to take during the pour

While the concrete is being poured, contractors should aim to match the speed of mixing with the speed of pouring. In other words, new concrete batches should be mixed just in time for use, when the old batch runs out. This will reduce any waiting time between pours, where the concrete will start to set before it is used.

Towards the end of the concrete pour, the contractors who are mixing the batches need to be informed. This will allow them to stop mixing new concrete in time and to avoid extra concrete supply that will go to waste. Communication is a key factor in minimising concrete wastage during the pour.

In situations where unexpected delays and issues stop the concrete pour, the supervisor needs to have a plan for the concrete being mixed. Using mechanical mixers can help in these situations as they continue to churn the mix and prevent it from setting. Manually mixing concrete can be affected by delays in a pour.

Contractors should always aim to use any leftover concrete elsewhere on the site in order to avoid wastage. This is why planning, communication and timing are such important factors on any construction project. Steps need to be taken before and during a concrete pour to minimise the wastage on-site.

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LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges. 

___

LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in Mbeya, Southwest Tanzania.

___

At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.

___

Follow us on Facebook, Twitter, LinkedIn and Pinterest for the best tips on construction, handy projects and the latest industry news. See our Instagram channel for more insights into our products.

How to install windows in a brick wall

How to install windows in a brick wall

Every house, office and shop needs windows. Any space that will be used by people will need natural light and a breeze. Windows are a vital component of any structure as they brighten up the interior and allow fresh air to enter the building. Every contractor will need to know how to install windows in a brick or concrete wall.

Firstly, the wall will need to be built and the lintels installed. If a contractor wants to create a window in a solid brick wall, they will need to remove some bricks and insert steel reinforcement pillars to hold the bricks up above the window opening. A concrete lintel can then be created and placed above this opening.

Making a hole for windows in a solid brick wall

  1. Mark out the position of the window on the brick wall using a tape measure and chalk.
  2. Look for any hidden obstacles in the wall that could pose a problem, such as internal wiring, plumbing and air vents.
  3. Remove a few bricks at the top of the marked area to make a small opening where the window will be placed. Make sure that the wall is strong enough to support the weight above the window hole before removing too many bricks.
  4. Remove bricks from the top to the bottom of the opening.
  5. As you remove more bricks, install metal jacks or use wooden planks to support the weight of the bricks above the opening.
  6. Cut the bricks that jut into the opening with a circular saw to create straight edges that are perpendicular to the plane of the brick wall.

Construct the lintel for the top of the window opening

  1. Remove about 20cm of the top three layers of bricks at the top of the window opening. This is where the lintel will be installed.
  2. Measure the length and width of the lintel space – it should be 40 cm wider than the rest of the window gap.
  3. Create a wooden formwork of the same length and width. The formwork must be three bricks in height.
  4. Mix some concrete and pour it into the formwork to create a solid concrete lintel. Leave it to set for 24 hours.
  5. Remove the formwork once the concrete has set and leave it to cure for another seven days. Remember to keep the concrete lintel damp during this curing phase.
  6. Use a crane or a pulley system to hoist the concrete lintel into place at the top of the window gap. Use some mortar to secure the lintel in place. It will now support the weight of any bricks above it.

Installing the windows in the brick wall

  1. Decide whether you want to build a window sill. If so, place some bricks along the bottom of the window opening at 90-degrees to the rest of the bricks in the wall. Using mortar, secure these bricks in place at a slight angle, so that any water on the outside of the window will run off the sill.
  2. Next, install the metal window frame in the opening in the wall. Use mortar and self-tapping concrete screws to secure the frame in place. Fill in any bigger gaps between the frame and the bricks with mortar.
  3. Leave the mortar to dry and set for 24 hours before installing the window glass. 
  4. Carefully insert the glass panel into the metal frame, starting with the bottom edge first. You may need to gently tap the window along the edges to make sure that they sit level with the frame.
  5. Apply window putty along the four edges of the window. While the putty is still mouldable, scape off the excess at an angle to make it look clean and smooth. Leave the putty to dry properly before painting the window frame or opening any windows.
  6. Check the waterproofing of the window by spraying it with a hose once everything is dry and set. Any leaks along the frame will need to be sealed with more putty or with silicone sealant.

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LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges. 

___

LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in Mbeya, Southwest Tanzania.

___

At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.

___

Follow us on Facebook, Twitter, LinkedIn and Pinterest for the best tips on construction, handy projects and the latest industry news. See our Instagram channel for more insights into our products.

How to plaster on masonry surfaces

How to plaster on masonry surfaces

Plaster is a thin layer of smooth mortar that is applied over bricks or concrete to act as a protective and decorative cover. It also provides an ideal surface for the coats of paint that will be applied to a wall. LafargeHolcim Tanzania manufactures TemboFundi – a masonry cement that can be used to plaster walls and other masonry surfaces. 

A masonry surface can be made from brick and mortar, stone, slate, tile or concrete. The masonry surface should be a bit rough before the plaster is applied – smooth surfaces do not hold the plaster as well and this can result it chips being formed. Here are the steps to plaster on surfaces:

Prepare the masonry surface for plastering

  • Keep all the mortar joints on the surface rough. This acts as a good bonding surface that holds the plaster.
  • Clean all the joints on the masonry surface with a wire brush to remove oil, grease and soil.
  • Fill any deep holes or cavities with mortar before plastering.
  • If the masonry surface is smooth, or if it has been plastered already, then chip out the surface to a depth of 12 mm to create a rough surface to which the new plaster can bond.
  • Spray some water on the masonry surface and keep it damp for at least six hours before the plaster is applied.

Lay the groundwork for the plaster

  • The aim to get a uniform thickness of plaster across the entire masonry surface. To do this, fix dots of plaster to the wall at regular intervals. These dots should be 15 mm across and about 10 mm thick.
  • Fix the dots horizontally across the masonry surface, then vertically to create a grid of plaster. The gaps between dots should be about on metre.
  • The thickness and alignment of the dots can also be checked using a plumb-bob or weighted string.
  • After fixing the dots, lay a vertical strip of plaster between them. This is called a screed. The screed will serve as a guide for maintaining the thickness of the plaster across the entire masonry surface.

Apply the base coat of plaster

  •  If the masonry surface is brick and mortar, the first coat of plaster should be 12 mm thick. If the surface is concrete, the plaster should be between 9 and 15 mm thick.
  • Make the plaster mix with the appropriate ratio of cement, sand and water.
  • Apply the first coat of plaster in the spaces between the screeds. Use a trowel to achieve a smooth surface.
  • Level the surface using a wooden float or a straight edge.
  • After levelling, leave the first coat to set. Then, scratch it with a tool to form a rough surface in preparation for the second coat.

Apply the finishing coat of plaster

  • The thickness of the second coat of plaster should be between 2 and 3 mm.
  • The ratio of cement and sand for the finishing coat should be between 1:4 and 1:6.
  • Damp the first coat of plaster with a quick spray of water. There should be no drops of water when the finishing coat is applied, just a damp surface.
  • Apply the last coat of plaster using a trowel and smooth it with a wooden float.
  • The final coat should be applied from the top of the masonry surface to the bottom. Do this in one operation to prevent joining marks.

Leave the plaster to cure

  • After the two coats of plaster have been applied, keep the surface damp with a sprinkle of water. This surface should be kept moist for at least seven days in order to cure properly.
  • If the plaster is left to dry out or if it does not cure properly, it can lead to cracks and the formation of efflorescence on the surface.
  • Keep the surface of the plaster clean before applying any coats of paint.

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LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges. 

___

LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in Mbeya, Southwest Tanzania.

___

At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.

___

Follow us on Facebook, Twitter, LinkedIn and Pinterest for the best tips on construction, handy projects and the latest industry news. See our Instagram channel for more insights into our products.

How to fix foundation damage on your home

Foundation damage crack in concrete

Foundation damage to any building can occur in a number of ways, from weak soil to water damage. A concrete foundation can be a difficult structure to repair, so it’s best to look after your foundations and maintain them regularly. Keep an eye out for any signs of damage and fix them as soon as possible.

It is possible to repair foundation damage without having to demolish the building, but the process can be time-consuming and sometimes expensive. Foundations are the main support structure of a building. As such, they are an integral part of a building, acting like the skeleton upon which the rest of the structure is built.

Causes of foundation damage

Concrete foundations are strong and durable. However, other problems can occur that affect the strength of these structures. Most of the time, the type of soil and moisture in the ground are the cause of foundation damage. If the soil is saturated with water, it can move beneath the foundations or cause moisture damage to the concrete.

A building can be at risk of foundation damage if:

  • It is built on clay or sandy soil. 
  • If the soil around the foundations has inadequate drainage.
  • The region experiences extreme seasonal changes.
  • There is a major plumbing or water leak underneath the building.
  • Tree roots are growing too close to the foundations.
  • A flood, drought or earthquake affects the soil around the structure.

These problems cause the soil around the foundations to move. This movement is then directly transferred to the foundations themselves, which can cause cracks to form. This can cause the building to weaken and will affect its resale value. The longer foundation damage is left, the worse the resulting problems will become.

Signs of foundation damage

How can you tell if a building has foundation damage, especially if the foundations are below ground? These are the most common signs of stress and damage:

  • Walls leaning, rotating or cracking.
  • Separation of concrete around doors, windows and corners of walls.
  • Extended cracks up the side of the building.
  • Displaced mouldings.
  • Cracking and chipping of concrete where the building meets the ground.
  • Cracks along the floor of the building.
  • Uneven floors and misaligned internal features (like doors that won’t close).

The most common sign of foundation damage is the appearance of cracks on the interior or exterior of the building. Horizontal cracks or jagged cracks along brickwork are the most serious indication of foundation damage and should be addressed immediately.

Methods to repair concrete foundations

The most ideal repair methods are those that don’t require occupants to vacate the building or move their belongings. Luckily, with modern building techniques and technology, there are a few ways in which foundations can be fixed without causing disruption to home life or business.

The two most common solutions are slabjacking and hydraulic jacking. In a slabjacking repair, grout is pumped beneath the foundations to produce a lifting force that restores the foundations to their original elevation. In a hydraulic jacking repair, steel posts are driven into the unstable ground and hydraulic jacks are used to stabilise the concrete foundations.

These methods of repair are used to fix different types of foundation damage. Before deciding on a repair method, you will need to determine what is causing the foundation stress. Get a contractor to look at the cracks and correctly determine the best repair method to use. Slabjacking is suitable for smaller repair jobs whereas hydraulic jacking may be required for bigger problems, where the soil is fundamentally compromised.

Remember to inspect your foundations regularly to catch any issues early on. Regular maintenance will also avoid further problems caused by shifting soil, excess water in the ground and tree roots moving concrete foundations. Always fix any cracks as they appear and contact a professional contractor if you believe that your foundations are compromised.

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LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges. 

___

LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in Mbeya, Southwest Tanzania.

___

At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.

___

Follow us on Facebook, Twitter, LinkedIn and Pinterest for the best tips on construction, handy projects and the latest industry news. See our Instagram channel for more insights into our products.

How to keep polished concrete shiny

Polished concrete floor

Polished concrete floors can be a beautiful look for any home, office or retail space. The polish adds durability to the concrete surface, protecting it from scratches and scrapes. However, polished concrete surfaces tend to lose their sheen over time, so they do require good maintenance.

Floors in high-traffic areas such as shops and commercial facilities should be polished regularly to keep them looking clean and shiny. However, these types of floors are easier to maintain than other decorative concrete surfaces as they do not require additional waxing or sealing.

Daily cleaning for polished concrete floors

You should try to sweep or mop polished floors once a day to remove any dirt that might scratch the polish. Dust, sand and dirt are abrasive and can remove the polish easily if they are not cleaned daily. Remember to use clean water and a neutral-pH detergent when mopping polished concrete floors.

Try to use a soft mop or cloth to clean the floor so that it does not scrape the dirt across the polished surface. The more traffic across the floor, the more often it should be cleaned. Here are some tips for keeping your concrete floor shiny:

  • Dust mop the floor every day with a microfiber cloth to keep dust and soil off the floor. These particles are abrasive and can ruin the shine of polished concrete.
  • If you are wet-mopping the floor, use clean water and a soft mop. Try to use a neutral-pH cleaner (one that is not acidic or alkaline) to protect the polish.
  • Clean spills from the floor as soon as you can to prevent them from becoming stains. Once a liquid is absorbed into the polish, it can become difficult to remove.
  • Give your detergents enough time to break down tough grime, such as grease or oil. These cleaning agents need to sit on the surface of the concrete floor for a few minutes to loosen the dirt.
  • Do not let the detergents dry on the surface as they can stain the polish themselves. Clean small areas at a time to prevent this from happening.

By following these tips, you will keep your polished floor looking clean and shiny, no matter how many people walk across the surface. A daily cleaning routine will increase the lifespan of your concrete floors and ensure that the polish lasts a long time.

___

LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges. 

___

LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in Mbeya, Southwest Tanzania.

___

At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.

___

Follow us on Facebook, Twitter, LinkedIn and Pinterest for the best tips on construction, handy projects and the latest industry news. See our Instagram channel for more insights into our products.

How to make a sloped edge on concrete floors

Sloped edge on concrete curb

A sloped edge on concrete can have safety and decorative aspects. It removes sharp edges of concrete and also enhances the look of floors and walls. A sloped edge can also make it easier to remove wooden formwork from concrete that has hardened. Also called a chamfered edge, these slopes prevent concrete from chipping or cracking at the corners.

There are two common ways to make a sloped edge; by using chamfer strips or by using chamfer edge tools.

1. Using chamfer strips

This method of sloping concrete edges is done before the concrete is even poured. Chamfer strips are placed into the corners of the wooden formwork or mould, along the edges. Chamfer strips come in a variety of sizes that determine the angle and width of the sloped edge. They are either made from rubber or wood. Concrete is poured into the formwork and the chamfer strips give it sloped edges from the start.

2. Using chamfer edge tools

This method of sloping edges uses specialised tools once the concrete has been poured and the surface water has dried off. The chamfer edge tools are capable of creating sloped edges of various sizes. This process requires skilled labour and a steady hand to make the concrete edge smooth and straight.

How to make a sloped edge on concrete with chamfer tools

  • Allow the concrete to set until there is no more water on its surface. This should take about 30 minutes from pouring and smoothing with a float.
  • Use the edging tool to bury any crushed stone below the surface of the concrete. Grab the handle of the tool and insert the lower edge of the seam between the edge of the concrete and formwork. Use the inner face of the formwork as a guide and run the tool back and forth using long strokes.
  • Repeat the above step with the chamfer tool but use light pressure to create a smooth and even edge. 
  • Leave the concrete to cure for two hours, or until a light swipe with a trowel does not scratch the surface.
  • Remove the formwork using gentle taps with a hammer.
  • Fill a bucket of water and dip a rubber float into the water. Use small strokes with the wet float to smooth the sloped edges. Dip the float into the water frequently for the best results.

___

LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges. 

___

LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in Mbeya, Southwest Tanzania.

___

At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.

___

Follow us on Facebook, Twitter, LinkedIn and Pinterest for the best tips on construction, handy projects and the latest industry news. See our Instagram channel for more insights into our products.

What to do with leftover concrete blocks

Repurposed concrete blocks

If you have leftover concrete blocks from a construction project, don’t throw them away. These building materials have many creative uses in the home, from creating benches to becoming pots for plants. Concrete blocks are a versatile and durable product that lend themselves to many uses.

If you don’t have leftover concrete blocks but still want to try some of these projects, you can easily make some soil-stabilised bricks yourself. Or, you can use Tembo cement and TemboFundi to create your own concrete blocks. Here are a few ways to repurpose concrete blocks in the home.

Use concrete blocks to make shelves

Whether you need to create space for some books or want some extra storage room, concrete blocks are ideal for making quick and easy shelves. You’ll need some extra timber to form the actual shelves and the concrete blocks will form the solid support.

To make the shelves, use two upright concrete blocks as the base, as wide apart as the lengths of timber. Place a piece of timber across the top of the concrete blocks. Put another two concrete blocks on top of the piece of wood and repeat this process of building simple shelves.

The weight of the concrete blocks will keep the wooden shelves secure. Make sure that you build the shelves on a perfectly level floor otherwise they may fall over. Three or four layers of blocks should be ideal for a sturdy set of shelves for books, tools and papers. You can make the shelves in the home, an office, a garage or outside.  

Make a bench seat from concrete blocks

Like a set of shelves, all you need to make a bench seat is some concrete blocks and timber. To make the bench, start by placing eight concrete blocks upright on the ground – four on each side of the bench. If you’re building the bench outside, you may want to dig a small hole to secure the blocks in the soil and make them perfectly level.

Place another two concrete blocks horizontally on top of the four base blocks, repeat for the other side of the bench. Next, slot your timber through the holes in the top layer of blocks, joining the two sides of the bench. There should be four holes on the top layer of blocks, so you’ll need four pieces of wood.

If you have spare cushions or pillows, place them on top of the wooden slats for added comfort. If you build the bench against a wall, you can use the wall as a backrest. This type of bench can be made inside or outside and it costs next to nothing to build. You can even build a bench in a square around a fireplace.

Use concrete blocks as pots for plants

Concrete blocks make the perfect pots for plants – the two holes in each block can be filled with gravel, soil and mulch. Even half-block can be used as a single pot. Contractors often leave half-blocks after a project, so you may have more of these lying around.

Place the concrete blocks on the ground so that the holes point vertically. Put a layer of small crushed stones at the bottom of each hole to help with drainage. Next, fill the hole with soil and plant some herbs, smalls vegetables or flowers. Add a layer of mulch on top of the soil for added moisture retention.

Remember to water the plants often and put the concrete blocks in an area with enough sunlight. You can also stack the blocks to create a garden feature or wall of plants. The blocks can also be painted to match the colour of the house or to stand out in the garden.

Make an outdoor table or countertop

You can use old concrete blocks to build a useful outdoor table or countertop. This project does require some building knowledge and cement skills. You’ll need some cement to create the four pillars (or legs) of the table.

Mix a batch of concrete using Tembo cement, sand and water. Dig a small hole in the soil for each concrete pillar and pour in a layer of concrete to make the foundations. Let the concrete dry for two days. Then, build the four pillars using concrete blocks and cement. The pillars can be four or five blocks high, or about 1,5m tall. Let the concrete cure for two weeks.

Use some lengths of wood and attach them to the top of the four pillars using 90-degree brackets and some screws. The wooden top makes a great surface for the table or countertop and is ideally suited for outdoor use.

If you have any concrete blocks left over from a building project, make use of these ideas to create some useful furniture or features for your home. There are many ways to repurpose concrete blocks, it just takes some creative thinking.

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LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges.

___

LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in Mbeya, Southwest Tanzania.

___

At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.

___

Follow us on Facebook, Twitter, LinkedIn and Pinterest for the best tips on construction, handy projects and the latest industry news. See our Instagram channel for more insights into our products.

How to test compressive strength of concrete

Compressive strength test concrete cylinders

Concrete mixtures can have different strength, durability and performance abilities, depending on the type of aggregates and cement used. This means that various concrete mixtures are suited to different applications and structures. The strength of a concrete mixture can be determined by a compressive test.

This test involves placing a cylinder of dry concrete underneath a hydraulic press. The concrete is crushed by the press and the strength of the mixture is calculated when the concrete gives way. This type of test is regularly performed by engineers and cement manufacturers as they research stronger concrete mixtures.

What is the compressive strength of concrete?

The compressive strength of concrete is a numerical value calculated in megapascals (MPa). Compressive strength requirements range from 17 MPa for general purpose concrete to 70MPa for large load-bearing structures such as bridges. It is important to work out the compressive strength of concrete mixtures to ensure that the concrete will be ideally suited to the job.

In most cases, the test cylinders of concrete have been left to cure for 28 days before being placed in the hydraulic press. Two or three concrete cylinders are tested and the average of the results is then determined to be the compressive strength of the concrete mix.

How to test the compressive strength of concrete

The concrete cylinders used for the compressive strength test have standardised dimensions of 150mm by 300mm or 100mm by 200mm. The smaller dimension is the diameter of the cylinder, the larger dimension is the height of the cylinder. These standard dimensions ensure that the same volume of concrete is tested, no matter where in the world they take place.

The concrete cylinders are then weighed and capped with either sulphur mortar or a neoprene pad. These caps provide a flat surface and a bit of protection for the hydraulic press plates. They do not affect the compressive strength reading.

The cylinders are loaded into the centre of the hydraulic press one at a time. They are then compressed until the concrete fails. The type of break is important to note – does the concrete cylinder crack down the middle or do the edges give way first? The most common type of break is a conical fracture where the middle section of the concrete breaks away, leaving behind two cones of concrete at the top and bottom of the cylinder.

The compressive strength is calculated by dividing the maximum load at the failure by the average cross-sectional area of the cylinder. At least two cylinders are tested and the average compressive strength is calculated to the nearest 0.1MPa.

Some concrete mixtures are tested at three or seven days to determine the early strength capabilities of the batch. These early tests are particularly important for concrete that requires early strength, such as arches and pillars. The results of compressive strength tests allow cement manufacturers and contractors to ensure that the right concrete is used for the right structure.

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LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges.

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LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in the Mbeya Region in Southwest Tanzania.

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At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.

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How to cut control joints in concrete slabs

How to cut control joints in concrete slabs

Like metals, concrete also expands and contracts with changing temperatures. During the heat of the day, concrete expands very slightly. At night, it shrinks. This daily fluctuation in size is very small, but flat concrete surfaces (such as pavements and driveways) can develop cracks if they do not have control joints.

These control joints are cuts in the surface of the concrete that allows each section to expand and contract without cracking. The depth and position of the control joints determine their effectiveness in preventing cracks. Here are the best ways to cut control joints in concrete slabs.

When to cut control joints

There are various factors to consider when cutting control joints, such as the time of day, the type of concrete used, weather conditions and the type of machinery used to make the cut. The best tool to use is an electric circular saw blade – make sure the disk is designed for concrete, not wood.

Avoid cutting the joints before the concrete has fully set as this could weaken the concrete at the edge of the cut. Allow the slab to set for a few hours before cutting control joints. In hot weather, sawing can be done about four hours after the concrete is poured. In cold weather, wait 12 hours after pouring before making the cuts.

Position of the control joints

Control joints should be cut at regular intervals along the concrete slab; each segment should be of equal length. The ideal spacing of the control joints should be about 30 times the thickness of the slab – so a 5cm thick concrete slab should have control joints every 150cm.

The control joints must extend across the entire width of the slab. If the concrete is reinforced with steel rebar or rods, try to determine where there is no reinforcement and make the cut there.

Depth of the cut

The control joints should be cut to a depth of one-quarter to one-third of the slab. A 12cm thick concrete slab should have a 3cm to 4cm deep control joint. This is a general rule for all concrete slabs.

If the cut is too deep, the concrete segments could become completely detached from one another. If the control joint is too shallow, it will not do its job and the concrete slab could crack at any point along its length.

How to cut control joints

Before cutting the joints, mark their positions on the surface of the concrete with some chalk. This will allow you to see if they are evenly spaced and perfectly straight before making the cut. The best tool for the job is a circular cutting disk, but water-cutting equipment is suitable too. Manual cutting is not recommended.

Set the disk depth on the saw to match the depth of the cut. Turn the machine on and carefully follow the chalk line on the surface of the concrete. Remember to wear proper safety gear such as gloves, dust masks and goggles. Blow the control joints after cutting to remove excess concrete powder and fill it with foam or silicone.

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LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges.

___

LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in the Mbeya Region in Southwest Tanzania.

___

At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.

___

Follow us on Facebook, Twitter, LinkedIn and Pinterest for the best tips on construction, handy projects and the latest industry news. See our Instagram channel for more insights into our products.