How to fix common concrete slab problems

How to fix common concrete slab problems

When working with concrete, contractors may encounter a few different problems. The following issues can sometimes occur when pouring concrete slabs. While some aspects of working with concrete slabs have changed over the years, many issues have not. Here are three common problems that come with pouring concrete slabs, and their possible solutions.

1) Excessive Bleeding

Bleeding occurs when the heavy ingredients in concrete (aggregate and sand) settle and push the extra water to the top of the slab. Concrete that bleeds for too long or too fast can cause problems like sand streaks in walls; weak horizontal construction joints; rock jams in pump lines; etc. Finishing a concrete slab before bleed water has evaporated can cause cracking, dusting, scaling and low-wear resistance.

Excessive bleeding can be avoided by not adding too much water to the concrete; placing concrete at the lowest possible slump (if you need a higher slump to speed placement, consider using a superplasticizer); using a more finely ground cement; adding more cement to the mix; blending in a fine blow sand or fly ash.

2) Curling

Curling happens when a slab rises up at corners and edges – or sometimes at a mid-panel crack. It happens when the top section of a concrete slab dries or cools faster than the bottom section. Curled concrete slabs can be fixed, but it is expensive. 

Grinding can level out the edges, and grout can be used to restore support to the slab. The best way to avoid curling is to control it before it happens. There are a number of material choices, construction practices and design decisions that will help prevent curling from happening in the first place.

3) Thin slab

All concrete slabs have varied thicknesses – some parts of the slab are thicker than others. When it comes to thin slabs, the thinnest sections may be too thin to retain their strength and may be prone to crumbling. In such cases, the contractor needs to decide how thin is too thin.

They must decide whether to make the slabs thicker for the sake of giving additional strength and durability to the concrete slab. Contractors should also pour thin slabs very carefully and ensure that the depth of concrete is even throughout the slab.

These are three of the most common problems that can arise when working with concrete slabs. They are easy to fix; taking care while pouring the concrete and being precise with measurements is the best way to avoid these problems in the first place.

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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.

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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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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 prevent dampness in a building

How to prevent dampness in a building

Dampness in a building may occur due to faulty construction, the use of poor-quality building materials or bad architectural design. Dampness affects the lifespan of a building or structure, but it also creates unhygienic conditions. Mold and fungi love to grow in damp conditions, so it is best to fix any signs of wet concrete as soon as possible.

The measures taken to prevent water from leaking into a roof is usually called waterproofing. The treatment given to a structure to keep its basement, floor and walls dry is called damp proofing. Some of the problems caused by dampness in a building include the disintegration of bricks, stones, tiles; the softening and crumbling of plaster; the corrosion of metals; the warping, buckling and rotting of timber; the presence of termites; deterioration to electrical fittings and the bleaching and flaking of paint with the formation of coloured patches.

What causes dampness in a building?

The absorption of moisture by building materials is one of the main causes of dampness. This can be caused by faulty structure design, bad workmanship or the use of defective structures or materials.

Sources of dampness in buildings include the rising of moisture through the foundation walling; splashing rainwater which rebounds after hitting the wall surface; penetration of rainwater through unprotected tops of walls, parapets or compound walls; gutters which allow rainwater to descend through the top supporting wall. In the case of buildings with flat roofs, inadequate roof slopes, improper rainwater pipe connections and defective junctions between roof slabs and parapet walls can also cause dampness.

How to prevent dampness in a building

1. Membrane Damp Proofing

This involves placing layers of water-repellant materials between the source of dampness and the structure. This type of material is commonly known as damp proof course (DPC). It could be made from materials like plastic or polythene sheets, cement-based concrete, bituminous felts or asphalt. Applying DPC in a basement is usually referred to as tanking and can prevent ground moisture from seeping into the concrete walls.

2. Integral Damp Proofing

This form of damp proofing involves adding certain waterproofing compounds to the concrete mix to increase its impermeability (resistance to absorbing moisture). The compounds made from sand, clay or lime help to fill the voids in concrete and make it waterproof. Compounds such as aluminium sulfate, calcium chlorides and alkaline silicates chemically react when mixed with concrete, producing waterproof concrete.

3. Surface Treatment

This type of treatment involves filling up the pores of the surfaces subjected to dampness. Water repellent metallic soaps such as calcium and aluminium oleates and stearates are often used for this purpose. Cement coating, transparent coatings, paints, varnishes and bituminous solutions also fall under this category. Another economical option for damp surface treatment is lime cement plaster. This effectively prevents dampness in walls as a result of rain.

4. Guniting

For this type of damp-proofing, a cement gun machine is used to deposit a layer of rich cement mortar over the surface. The surface must be completely cleaned of dirt, dust, grease or loose particles by wetting it properly. Cement and sand (or fine aggregates) are then fed into the machine. This mixture is finally shot onto the prepared surface under a pressure of 2 to 3 kg per square centimetre by holding the nozzle of the cement gun at a distance of 75 to 90 cm from the working surface.

5. Cavity Wall Construction

This form of damp-proofing consists of protecting the main wall of a building by an outer wall, leaving a cavity between the two walls. The cavity prevents moisture from spreading from the outer to the inner wall.

These five methods of damp-proofing will help to protect concrete structures from excess moisture, which can lead to mold, fungus, rot and damage to buildings. Contractors and homeowners must always inspect their buildings for any signs of stress and damage, such as dampness, which could affect the integrity and durability of the 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. 

___

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.

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How to prepare a concrete surface for a topping

How to prepare a concrete surface for a topping

Sometimes concrete surfaces are given a decorative topping that adds further protection and durability to a floor or carpark. The underlying concrete will need to be prepared properly before any topping is laid on top. This will ensure that a good bond is formed between the two materials and that no cracks or chips will form over time. 

When a bonded topping is being applied to a concrete surface, the concrete must be vacuumed and cleaned thoroughly first. This will remove any potential contaminants and dirt that could affect the bonding process. Even old adhesive from floor tiles that have been removed can be a potential contaminant for the new topping. Other common contaminants include oil, metal filings and paint spills.

The next step before the topping is applied to the concrete surface is filling and stabilising any existing cracks. Cracks have the potential to move and spread underneath a topping. This can obviously affect the bond between the topping and the underlying concrete. All cracks need to be filled with epoxy or stabilised with steel reinforcing bars.

Concrete surface preparation for a topping

Once the concrete surface is clean and any cracks have been eliminated, it can be prepared for the topping. The concrete must be scarified so than any coarse aggregate is exposed and the adhesive has a rough surface with which to bond. The scarification process can be carefully performed with a hammer and a chisel. Lines are chipped out of the concrete surface and any smooth sections of concrete can be lightly dimpled.

Be careful not to use too much force with the hammer and chisel as this can cause microcracking in the concrete. These hairline cracks could potentially grow into larger cracks a few years later, once the topping has already been applied. Some concrete slabs have a thick layer of mortar at their surface. In such instances, there is no need to expose underlying aggregate – just dimple the surface to create a rough area.

Second cleaning of the surface

After the scarification process, be sure to clean the concrete surface thoroughly once again. This is best done by brushing the concrete with a broom and cold water, then vacuuming any remaining dust once the concrete is dry. The dust in the concrete pores must be removed as it could affect the bond with the topping. Avoid using any chemical cleaners as they could leave an oily residue or stain the exposed, untreated concrete.

Saturated surface dry conditioning

Just as aggregates are supposed to be saturated surface dry (SSD) before being added to a concrete batch, so too should the concrete surface be SSD before the topping is applied. Many contractors believe that a dry concrete surface is necessary for a strong bond. However, an SSD concrete surface will prevent any water from being drawn out from the mortar or adhesive paste used to bond the topping to the concrete. However, be careful not to oversaturate the concrete surface as any standing pools of water in the pores will affect the bond.

Applying the bonding mortar or adhesive

In this step, it is important that the topping gets into full contact with the textured concrete base through the mortar or adhesive. Full contact ensures that the adhesive spreads evenly and thoroughly across the two surfaces, which increases the bond strength. If full contact is not achieved, the topping could peel away over time and lift, creating air bubbles underneath the surface.

The topping must also be placed before the adhesive dries out. If the bonding mortar or adhesive dries before the topping is applied, it can create a weak layer that is prone to lifting and cracking. However, do not add additional water to the mortar in an attempt to prevent it from drying as this could affect the overall strength of the bond. A plastic sheet may protect the mortar from the drying effects of wind and heat, so keep the adhesive covered until the topping is ready to be applied.

Once the topping is applied across the entire surface of the underlying concrete, leave it to dry and cure for 24 hours before walking or driving across the surface. As with concrete, the topping and adhesive will harden slowly over time. This will ensure that the topping is durable and lasts for many years to come.

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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 reduce the costs of formwork in construction

How to reduce the costs of formwork in construction

Construction projects can be costly processes, so contractors need to find ways to minimise these expenses without affecting the quality of their work. One simple way to minimise the expense of a building is to reduce the costs of concrete formwork. Sometimes formwork can account for up to 60% of the total budget for a building.

New materials, proper planning and prefabricated formwork components can allow contractors to reduce their building expenses without affecting the quality of their work. There are several other ways to reduce the price of formwork, such as using one system throughout the project, using standard form sizes and using the same level for all beams and joints.

Tips for minimising the costs of formwork

  • Use a single framing system for the whole project. This not only helps contractors to learn the formwork system easily, but it also helps to minimise the costs of the formwork set-up.
  • Use the same depth of formwork for all concrete beams. This will help to standardise beam size and shape, making the project quicker and easier.
  • Stick with the same formwork moulds for beams, even if the spans and loads of these beams are different. Contractors can modify the concrete ratios to compensate for various loads on beams.
  • Simplifying the formwork can also help to create uniform shapes and sizes for concrete pillars and beams. 
  • Reuse formwork as much as possible.
  • Use a constant floor-to-floor height between the different levels of a building. This will ensure standardised pillar heights and formwork moulds.
  • Orientate all framing in one direction to save money and time when pouring concrete into the formwork.
  • Consider flat plate formwork for concrete spans up to 7.5 metres as this framing system is the cheapest and fastest to construct.
  • Determine a standard time for the stripping of formwork from poured concrete. This will allow a project to run smoothly and on schedule.

These tips are based on a few general principles. Standardisation and time-management are two of the biggest factors that can reduce the costs of formwork. Contractors need to use standard formwork frames and create concrete beams and pillars of uniforms sizes. This helps to speed up the construction process and in this industry, time is money.

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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 set out a building plan on the ground

Architects building plan

Before contractors can begin a construction project, they first need to lay the building plans on the ground. This is the process of making the outline of the structure, to the exact dimensions, on the location of where it will be built. The building plan will show contractors where to dig and lay the foundations for the building.

The building plan is often marked by pegs and string, but some contractors like to use white paint on the ground. Pegs are hammered into the ground and attached by a string along the centreline of walls. Contractors need to make sure that the pegs and string follow the architect’s drawings perfectly. 

Steps to laying a building plan on the ground

  1. Clear any long grass and rocks from the construction site where the building will stand. Remove any debris and skim off the topsoil. This will make the marking process easier and clearer.
  2. From the architect’s drawing, start by hammering a peg into the ground at one of the corners of the building (call it point A). Measure the distance of the wall, using the architectural plan as a reference, and place another peg in the ground where the next corner of the wall will be (point B). 
  3. Place a peg two metres away from point A and point B and connect these two pegs with the string. These pegs (call them A1 and B1) will help contractors excavate the foundations later without having to move the string or corner pegs.
  4. Repeat this process of placing pegs at all the corners of the walls (points C and D) and placing additional pegs two metres away. Attach all the outer pegs with string. Each corner point should have two pegs (corner A will have peg A1 joining B1 and A2 joining D2). Where the strings cross will mark the exact corner of the walls.
  5. To make sure that the corners are 90°, the centre points of the rooms needs to be calculated. Measure the distance between opposite corners (point A and point C) on the architect’s drawings. Make sure that the real distance between the pegs at point A and point C match the distance on the drawing. You may have to move the pegs a bit to make these diagonal measurements are exact.
  6. Where the diagonal strings cross is the centre point of the room. The opposing walls (AB and CD or AD and BC) should be the same distance from this centre point.
  7. Once all the strings are laid, the contractors can start excavating the foundations. The extra two metres of string at each corner will allow the contractors to dig the foundations without having to excavate any corner pegs. The strings will be used as a guide for the centreline of the walls.
  8. Some contractors like to spray white spray paint on the ground or use lime to demarcate the path of the wall underneath the strings. This just helps to dig the foundation more accurately.

___

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 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. 

___

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 the workability of concrete on-site

How to test the workability of concrete on-site

There are a few ways to test the workability of concrete at a construction site, but three of the most common methods are the Vee-Bee test, slump test and compaction factor test. Different concrete mixes will have various values for these tests, depending on their applications. So, what is the workability of concrete?

The workability describes the ease or difficulty of the handling of a concrete mix. It is the dryness or liquidity of concrete that determines how easy it is to mix, transport, pour and place in formwork. The workability is an important factor for a concrete mix for a couple of reasons.

If the mixture is too wet, the coarse aggregates will sink and settle at the bottom of the concrete structure. As a result, the concrete will be non-uniform and have weakened integrity. If the concrete mixture is too dry, it will be hard to mix and place in position. It will also be prone to cracking.

Tests for the workability of concrete

As mentioned before, there are three common tests for concrete workability. These include:

  • Vee-Bee consistometer test
  • Slump test
  • Compaction factor test

The slump test is the only one that can be performed on-site. The Vee-Bee test and compaction factor test are usually performed in a laboratory or specialised facility.

How to perform a concrete slump test

A concrete slump test is performed on-site to determine the correct workability of a concrete mix. Contractors will use a cone-shaped mould that is 30cm high with a top diameter of 10cm and a bottom diameter of 20cm. The test is performed in the following steps:

  1. Place the slump mould on a smooth, flat, non-absorbent surface.
  2. Mix the dry ingredients of the concrete and then add the required amount of water, according to the instructions on the bag of cement.
  3. Fill one quarter of the slump mould with the concrete mix.
  4. Compact the concrete 25 times using a tamping rod.
  5. Place some more concrete in the mould, filling it half-way. Compact it again.
  6. Place more concrete in the mould, filling it three-quarters of the way. Compact again, 25 times. 
  7. Fill the mould completely and compact again. The tamping rod should penetrate all the layers to ensure maximum compaction and no lines of separation between layers.
  8. Scrape off any excess concrete from the top of the mould, using a trowel.
  9. Flip the mould over and place the concrete on the flat surface. Remove the mould in an upwards direction.
  10. Watch the concrete slump and settle. Once it has stopped moving, measure the subsidence (or how much the concrete sinks from its original 30cm height) in millimetres. This will tell the contractor how much the concrete will settle and how easy it will be to handle on-site.

Recommended values for the slump test

The slump test should only be used for concrete that is supposed to be of high or medium workability (i.e. stiff or semi-dry mixes, not dry mixes). The following table outlines the recommended slump value for various concrete applications:

Concrete applicationSlump
Road construction20 to 40 mm
Walls, slabs, piers, curbs40 to 50 mm
Normal reinforced cement concrete (RCC) work80 to 150 mm
Mass concrete20 to 50 mm
Concrete to be vibrated and compacted10 to 25 mm

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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 waterproof concrete structures

How to waterproof concrete structures

Waterproofing concrete structures can help to protect them from the weather and keep them in optimal condition. This is especially important in areas prone to flooding, heavy rainfall and constant ocean vapour. Water can penetrate concrete over time and affect its strength, so waterproofing is a good way to keep a building strong.

There are numerous ways to waterproof a concrete structure. Contractors can apply paints and bitumen felts to the exterior of the building, or they can use concrete admixtures to prevent water from penetrating the surface of the structure. For optimal waterproofing results, the design, workmanship and building materials should conform to the correct standards and codes of construction.

Concrete waterproofing admixtures

Certain admixtures make concrete impermeable to water and moisture. These chemicals can be added to the concrete or plaster batch during mixing. They reduce water permeability in the concrete by reducing the size and number of pores in the surface. They also line the surface with hydrophobic materials that prevent the absorption of water.

These admixtures react with the calcium hydroxide in the cement to create a hydrophobic layer. Examples of waterproofing admixtures include animal fats, stearic acid and some vegetable oils. These admixtures can also be mixed with plaster to line the surface of a wall. This acts like a layer of waterproof paint that repels rain, standing water and mist in the air.

Waterproofing concrete with bitumen coating

Another way to make concrete structures waterproof is to place a layer of bitumen on the exterior surface. The concrete first needs to be cleaned and sanded to give the bitumen a rough surface to stick to. Contractors should pour hot bitumen (about 1.5kg per square metre of concrete) onto the surface and spread it evenly. 

Once the first coat had dried and cooled, the second coating (1.25kg per square metre) is applied in the same manner. Immediately after the application of the second coating, contractors should spread sand over the surface. This is then left to dry and cool. The sand will give the surface a non-slip texture and improve the durability of the bitumen.

Certain concrete structures need to be waterproofed internally, such as concrete tanks and reservoirs that will store certain chemicals and liquids. Waterproofing a concrete structure will maintain its strength in the face of exposure to water and other liquids. It will prevent concrete rot and protect a building from heavy rains, flooding and salt moisture from the ocean.

___

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 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.

___

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 estimate the number of bricks needed for a project

How to estimate the quantity of bricks needed for a project

Before any brickwork construction can begin, the contractor first needs to order the building materials (bricks, cement, sand, etc.) and have them delivered to the site. To do this, an accurate estimation will need to be made of the volumes of building materials that will be required. The contractor has to consider how many bricks are needed for the total area of the building.

When making estimations, contractors often work out the number of bricks needed to fill a space of one cubic metre. Clay bricks tend to have a standard size (roughly 222mm long by 106mm wide by 73mm high). For one cubic metre of standard-sized brick masonry, a contractor will need 494 bricks. This equates to about 60 bricks per square metre of single-brick wall or 120 bricks per square metre of double-brick wall.

The contractor needs to calculate the volume (for a double-brick wall) or area (for a single-brick wall) by multiplying the width, length and height. This can be done according to the architect’s drawings. Once the contractor knows the area of the wall, they can use the above guidelines to place an order. They can multiply the area by 60 (for a single-brick wall) or by 120 (for a double brick wall).

Once the number of bricks has been calculated according to the size of the wall, contractors should always add a 10% allowance on top of that number. This takes into account any additional bricks needed for verges, pillars or to replace broken ones. It is always better to have a few extra bricks than not enough.

The contractor will also need to estimate the quantity of mortar needed for one cubic metre of masonry. On average, buildings will require between 0.25 and 0.3 cubic metres of mortar per cubic metre of brick. This means that between 25% and 30% of brickwork consists of mortar (or sand and cement).

Contractors can use these estimations as a guideline to know how many bricks will need to be ordered and what volume of sand and cement to have delivered. Running out of building materials will cause time delays and cost the contractor money. However, builders do not want to have hundreds of bricks leftover at the end of a project either.

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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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