How to speed up concrete drying time

How to speed up concrete drying time

Much of the time spent on a construction project is spent waiting for the concrete to cure and dry. However, this is an absolutely vital process as concrete that does not set, cure and dry properly will be flawed and prone to structural failure. The structure needs to be given enough time to harden properly before more work takes place on top of it.

In order to maximise the efficiency of the construction project, contractors can use several techniques to speed up the drying time of their concrete structures. This will help to keep the project on schedule without compromising the structural integrity of the concrete. These methods will allow contractors to maintain safety on-site, as well as meet upcoming deadlines.

Pre-pour tips for speeding up concrete drying time

  • Choose the best weather – Contractors need to keep an eye on the weather forecast. Concrete dries faster in dry and warm conditions. Luckily, Tanzania is warm and sunny for most of the year. Extremely hot weather can have several effects on concrete, so keep this in mind. If a project is running on a tight schedule, avoid pouring concrete in the rain as this will slow down the drying time.
  • Add warm water to the mix – Water is a key ingredient of concrete and is essential for the curing reaction to take place. Contractors can use warm water in their concrete mix to help speed up the curing process. The water can be left in a bucket in the sun, or added from a hot tap – it should not be boiling or too hot to the touch as this can damage the concrete.
  • Add calcium chloride to the mix – Calcium chloride is a concrete additive that can be mixed with the cement, water and aggregates. This chemical compound accelerates the process of hydration and helps the concrete to dry faster.
  • Reduce the amount of water in the mix – The more water you add to a concrete mix, the longer it will take to dry. Using less water will reduce the drying time, but be careful not to remove too much water from the mix. A dry concrete batch can crumble once set, so always use enough water to make a workable mix.

Post-pour tips to speed up concrete drying time

  • Trowelling technique – Avoid hard-trowelling as the increased pressure on the concrete can cause densification and collapse internal vents. This prevents moisture from evaporating from the concrete mix when drying. It will extend the drying time significantly.
  • Cover the concrete with a plastic sheet – Curing requires moisture on the surface of the concrete. It sounds backwards, but a damp concrete surface actually dries faster and with greater strength. Cover the concrete surface with a plastic sheet to prevent too much moisture from evaporating. The plastic sheet will also prevent excess atmospheric moisture from being absorbed into the concrete.
  • Use a heater – If the weather is overcast and cold, contractors can use heaters or heating mats to warm up the structure and decrease the drying time. However, take care not to overheat the concrete as this can bake the surface and cause it to crack. A gentle heat will help the concrete to dry faster.

These tips will help contractors to speed up the drying time of their concrete projects. They can be used before the concrete is poured and afterwards. A construction project that runs on-time will save money. So use these tips to speed up the process and meet all the required deadlines.

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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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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 strengthen concrete columns

How to strengthen concrete columns

Sometimes contractors need to restore old buildings or make repairs to damaged structures. When it comes to reinforced concrete columns, they need to be strengthened to ensure that they can carry the massive load of the building that they support. Buildings that have been damaged by earthquakes, such as the one that struck Tanzania in 2016, also need to be reinforced and have their columns strengthened once again.

How do contractors know when reinforcement is needed for concrete columns? If a building is being extended vertically – if more floors are being added – then the lower support columns will need to be strengthened. Alternatively, if the columns are showing signs of stress, such as cracking, bulging and bending, then they will need to be reinforced. 

This is why regular inspections of a building is important; these issues need to be fixed as soon as they are spotted. There are many ways to strengthen concrete columns in tall buildings, but the two most common methods will be outlined below. They are reinforced concrete jacketing and steel jacketing. 

Reinforced concrete jacketing

This technique is used to restore and improve the load-bearing capacity of concrete columns by increasing the cross-sectional area of the columns. The size of the concrete jacket and the number of steel rebars needed will depend on the structural diagnosis that the civil engineer made on the weakened column. To install reinforced concrete jacketing, the following steps must be taken:

  1. Place mechanical jacks and metal props (or scaffolding) between floors of the building. This will help to support the weight and reduce the loads on the concrete columns.
  2. Chip away some of the concrete on the columns to inspect the steel rebar inside. If it has rusted or corroded, then all of the concrete will need to be removed in order to clean the steel rebar with a wire brush or a sand compressor.
  3. Coat the steel rebar with an epoxy paint to prevent further corrosion.
  4. If the steel rebar inside the concrete column is not rusted or corroded, then the jacketing process can begin by adding steel connectors and rebar around the concrete column.
  5. These steel connectors are added to the column by drilling holes three to four millimetres larger than the diameter of the steel connectors. These drilled holes should be 10 to 15 centimetres deep into the four sides of the column, no more than 50 centimetres apart vertically.
  6. The stirrups of the jacket will be inserted into these holes. Fill the holes with an epoxy glue then insert the connectors into the holes.
  7. Drill similar holes into the floor and ceiling around the concrete columns. These will attach to the base and the top of the jacket.
  8. Install the new vertical steel rebar and stirrups of the jacket around the concrete column.
  9. Coat the existing concrete column with an epoxy glue.
  10. Mix a batch of concrete and place it around the existing column and the new steel rebar. Do this before the epoxy coat around the old column dries out. Leave the concrete to dry and cure before removing the metal jacks and supports between floors.

Steel jacketing

This technique is used when the loads applied to the columns will be increased, but increasing the cross-sectional area of the columns is not possible. These are the steps to take when attaching a steel jacket to concrete columns.

  1. Remove the surface layer of concrete from the column to expose the steel rebar.
  2. Clean the rebar using a wire brush or a sand compressor.
  3. Coat the steel rebar with an epoxy glue to prevent corrosion.
  4. Coat the concrete column with epoxy glue to ensure a solid bond between the column and the steel jacket.
  5. Using precut lengths of steel sheets, install the steel jacket around the column.
  6. Fill the spaces between the column and the steel jacket with more epoxy glue or mortar.

These methods of jacketing will strengthen concrete columns but giving added support. They can be used to restore old concrete columns or to repair damaged structures. Both of these methods will increase the load-bearing capacity of the concrete columns and improve the building’s safety.

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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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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.

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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 estimate the costs of a construction project

How to estimate the costs of a construction project

Working out all the costs involved in a construction project is very complicated and requires many factors to be considered. This skill of estimating costs takes a lot of time to learn. Studies, the right training, as well as practical experience is required in order to become efficient at estimating costs for construction projects.

There are many aspects of a building project that can influence the costs. The cost estimator should be familiar with all these factors. All aspects should be evaluated in detail before finalising a construction cost estimate. It is important to do the relevant research and to familiarise yourself with all of these factors before making a cost estimation.

Important factors to consider when estimating construction costs

  • The cost of similar projects – It is very helpful to study the cost estimates for similar projects. Study the final cost items and related expenses of other projects, similar to the project you are working on – it will be of tremendous help.
  • The costs of materials – The cost of supplies and materials, as well as their transport, must be calculated before you start the estimation process.
  • Inflation – If you are using previous, similar projects as a starting point for estimating costs, always remember to factor in inflation (the price increases and the decrease of the purchasing value of money over time).
  • The cost of labour – Work out the labour costs for your project in accordance to local labour rates, or as stipulated by your local government.
  • The conditions at the site – This can include things like the environmental sensitivity of the area, poor soil conditions, the presence of groundwater, archaeological sites or contaminated materials, as well as conflicting utilities, like buried pipes, cables, overhead lines, and so on.
  • Timing of the bid – Things like the seasonal time of year, as well as conflicts with other bid openings, can have a big impact on the cost of the project.
  • Plans and specifications – It is very important that all plans and specifications are well prepared, with every detail and aspect of the layout and design executed and fully described.
  • Project schedule – The timeline of the project is a critical factor. If it needs to be completed very quickly, this will generally make the project more expensive – in particular if a liquidated damages condition for failure to complete within a specified deadline is included in the contract.
  • Project engineer – Working with an engineering firm or project engineer that has a good reputation in the industry will ensure a smooth-running project, but might increase the costs. Keep in mind that, if a contractor enjoys working with a certain engineer or firm, the project will be more cost efficient and also likely run smoother.
  • Size of the project – The larger the project, the more bidders will likely be involved and the higher the costs. The size of the project will determine whether local contractors will have the capacity to do the work.
  • Granting agency – If a granting agency is involved in providing funding for a project, this will be taken into consideration when a contractor is preparing his or her bid. This might involve extra administration and paperwork, which can increase the cost of the bid.
  • Location of the work site – The location of the construction site is a big factor in working out a realistic cost estimate. If the location is remote, enough labourers to do the work may be scarce and labour will have to be imported, so driving up costs.
  • Contingency factors – Usually, a 10% contingency amount on the construction total is added to cover unforeseen costs that may arise as the project progresses. When inflation is at a high, or essential construction materials are limited, it may be best to play it safe and increase the contingency amount to 15% or 20%.
  • Regulatory requirements – Certain conditions in regulatory agency approvals can be costly. To reassure potential bidders, it is recommended to include all regulatory approvals in all bidding documents.
  • Value engineering – Certain agencies require that high-cost projects perform a value engineering review, before the design is finalised or before the bidding process proceeds. The estimator must be aware of this factor early on in the process.
  • Insurance requirements – A contractor’s general liability, performance bonds and payments are general insurance requirements, as well as normal costs of doing business. However, certain projects require additional coverage. Such insurance premiums (for supplemental policies) add to the cost of the project and must be factored in right from the beginning.

Cost estimation research is essential

Sound technical judgment is of utmost importance during the cost estimation process – this will come with experience, as well as from the mentoring of other experienced industry role players. It is imperative that research is undertaken to take all relevant factors into account when drawing up a cost estimate for a construction project. A detailed and thorough cost estimate will result in a smooth-running operation with the best possible outcome for all parties. 

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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 prevent salt damage to your concrete structures

How to prevent salt damage to your concrete structures

Salt is a natural mineral that can sometimes end up in your concrete mixture. It can either be present in the sand and aggregate or it can end up in the concrete if you are building in a seaside environment. It appears as white streaks or powdery crystals on the surface of cured concrete.

The effects of salt can damage concrete if left untreated, especially large areas of walls and floor. The problem is worse near the sea where salt in the wave spray and in the air can affect concrete structures. Constant exposure to salt can cause problems for concrete structures.

How does salt damage concrete structures?

Concrete is an alkaline material. Any exposure to mildly acidic substances or those containing chlorides could break the bonds between the cement and aggregates. Salt is sodium chloride, so it can weaken concrete and make it brittle in a few ways:

  • Salt can lower the pH of concrete. This makes the pores in the surface bigger which can allow more moisture, water and other chemicals seep into the concrete.
  • Salt is hygroscopic which means that it attracts and absorbs water. It can retain water in concrete which leads to damage, rot and increased pressure inside the structure.
  • Salt speeds up the carbonation process. Under ideal conditions, contractors want the carbonation process to be slow so that the concrete can cure properly.
  • Salt introduces chlorides to the concrete. These chlorides seem up concrete corrosion and make the structure brittle.

How to treat salt damage in concrete

The first sign of salt in concrete will be white streaks or a white powder on the surface of the structure. To treat salt and prevent further damage, rinse the surface of the concrete with clean water. Scrub the salt away with a brush, leaving no white substance behind.

Next, apply a good sealer to the surface of the concrete to prevent salty moisture from entering the concrete. Sealers help to keep water and moisture out of the concrete pores. Ideally, you will want to use a sodium or lithium silicate densifier sealer as these chemically react with salt in the concrete to permanently protect the structure.

If you cannot get a proper concrete sealant, then apply a protective coating to the surface of the concrete. This could be a layer of plaster or a few coats of paint – ideally, both will help to form a protective coating that will prevent salty moisture from penetrating the surface of the concrete structure.

The best way to prevent salt damage, however, is to ensure that you use clean water when mixing the concrete and use sand from a freshwater river bed. Then, apply a sealer or protective coating as soon as the concrete has cured. Prevention is the best cure, so look after you concrete structures from the outset – especially in coastal environments.

___

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.

Tips for mixing and casting concrete slabs

Pouring a concrete slab

Casting a flat concrete slab may seem like an easy task, but there are some important details to remember that will make process safe and successful. One of the first things that contractors will learn on the job is how to pour a flat slab of concrete, whether it is for a floor, countertop or a base for an object.

Here are some things to consider before, during and after pouring concrete slabs. These tips will ensure that you don’t waste money or time during the process. Once you have built the wooden formwork and mixed the batch of concrete, remember the following points:

Safety is paramount

All contractors should wear appropriate safety gear when working with cement and concrete. Workers should have dust masks, goggles, gloves, boots and overalls. Appoint one employee to perform a quality check of the building materials and equipment before mixing the concrete. 

This will ensure that everything is in working order and that a high-quality batch of concrete is created. It will also ensure the safety of other contractors as faulty equipment, such as cement mixers, could lead to injury. This designated worker can also file safety reports and create quality checklists if needed.

Create a detailed batch report system

Before mixing the concrete, print out a detailed batch report that lists all the building materials needed and their quantities for each batch. When measuring out the sand, gravel, cement and water, put a tick beside each material. When adding the materials to the mixer, put another tick next to each item on the list.

This double-tick system will help you keep a detailed record of your building materials and see if there are any discrepancies or losses. It will also help you to accurately calculate how much concrete you will need to mix for the slabs. The batch report can be used for future reference so that you can easily recreate the slab with the correct quantities of materials.

Keep materials, tools and equipment nearby

It will help you to keep all of your building materials (sand, gravel, cement and water) near to the location where you will pour the concrete slabs. Also have all the necessary tools and equipment nearby. This will save time and effort when you need to quickly add some more materials to the concrete batch. It also makes it easier to carry heavy bags of cement or wheelbarrows of sand if they are stored close to the working site.

Pour multiple slabs from the same batch of concrete

If you are pouring several slabs at once, it is important to mix a large batch of concrete and use it to pour all the slabs, rather than mixing a small batch for each individual slab. This will ensure quality and consistency between all the slabs. Any variation in the ratios of wet and dry ingredients will easily be seen in the slabs. By mixing one batch of concrete, you will end up with identical slabs. 

Add materials to the mixer in the correct order

There is actually an ideal order in which building materials should be added to a cement mixer; sand and gravel go in first, followed by water and any admixtures. Next add any fibres and pozzolans. Lastly, the cement should be added gradually to the mixer.

The reason for following this order is simple; if you add cement first, followed by water, it can clump inside the mixer. Mixing the sand and gravel with water first ensures that all of the aggregates are wetted and dispersed. When the cement goes in last, it will combine nicely with the other materials to form a high-quality batch of concrete.

Some other points to remember

If you are hand-packing a stiff batch of concrete into a wooden form, make sure that the concrete goes into every edge and corner of the mould. If you are pouring a fluid mix of concrete, make sure that you release all the trapped air bubbles by tapping on the side of the formwork. 

If you are using steel rebar for reinforcing, make sure that it is suspended in the middle of the concrete batch and that no rebar stick out of the surface of the slab. These are some of the points to remember when pouring concrete slabs. Some of these details can be overlooked, which could affect the quality of the slab, so keep these tips in mind.

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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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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 chemicals to use on concrete stains

What chemicals to use on concrete stains

While water is usually enough to remove dirt from concrete, you often need the help of chemicals to clean tough stains. From oil and grease to rust and graffiti, chemical cleaners will make the task of cleaning concrete much easier. 

Many contractors will recommend spraying the stain with the cleaning agent and leaving it to soak for about 15 minutes before using a high-pressure water spray to wash it away. Concrete is slightly alkaline because of the lime in the cement, so we suggest using an alkaline cleaning agent rather than an acidic one.

Oil and grease stains

One of the most common types of concrete stain is caused by oil. Parking lots, roads, pavements and garage floors are all victims of dripping oil from vehicles. Workshop and industrial floors can also suffer from grease stains. The best way to clean these surfaces is to use an alkaline degreaser with hot water.

The degreaser will improve the removal rate of these stains by emulsifying the oil and grease. The hot water will help to lift the oil from the concrete surface. Using a high-pressure water jet will also help to remove the tough stains in the pores of the concrete surface. Alkaline degreasers can also be used to clean soot and soil stains too.

Rust stains on concrete walls

Rust stains can either have a golden-brown appearance or a blue-green colour. They commonly occur on concrete walls around exposed pipes, metal brackets and bolts. Heavy rust stains can sometimes penetrate deep into the wall.

The golden-brown stains occur when steel oxidises and rusts, whereas the blue-green markings happen around copper water pipes. The best cleaning agents to use for these stains are the ones that contain oxalic acid. This chemical helps to break down the metals in the rust stain and make it easy to wash away with a hose or a water jet.

Graffiti on concrete walls

Graffiti on a wall can be very difficult to remove. The type of spray paint used will determine how much effort you need to clean it off. The best way to remove paint stains is to use a chemical stripper that contains a citrus-based solvent, methylene chloride or potassium hydroxide.

The citrus-based solvents are the least aggressive and safest cleaners, which is good for your concrete wall but not as effective at removing graffiti as the other two chemicals. Cleaning agents that contain potassium hydroxide are the best for paint stains. Spray them on the wall and allow it to soak for several hours before spraying the wall with a high-pressure hose. You will also need to spray an acid neutraliser on the wall after the cleaning process to protect the concrete from acid damage.

Another method of cleaning graffiti from a wall is to use a special attachment fitted to a water jet nozzle that feeds sand into the water stream. This essentially sandblasts the paint off the wall. While this method is safe and clean, it can damage the surface of the wall.

These tips will help you remove the most common types of stains from your concrete floors and walls. Water and a cleaning chemical will always give you the best results, but it is important to know what type of cleaning agent to use for each stain.

___

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.