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. 

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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 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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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.

Types of inspection for concrete structures

Inspection of concrete bridge

Inspecting concrete is a necessary step in the proper maintenance of buildings and  structures. It allows contractors to find any faults, such as cracks and salt damage, before they become bigger problems. Inspections will provide assurance that the concrete is structurally safe at any given period, so they need to be performed once every couple of months at least.

During inspections, any defects or problems need to be recorded. This allows contractors to keep an accurate record of when issues occur and how they are resolved. This information can also help engineers and architects to plan the repair work and strengthen the concrete structure.

Types of concrete inspection

There are three main types of inspection that need to be performed on concrete structures. These are; routine, detailed and special inspections.

  1. Routine inspection – This is the examination of concrete structures at regular intervals. Routine inspections are usually quick and they only look at the general condition of the structure. Each examination is recorded in a book. The inspector will make a visual assessment and use simple tools to determine the condition of the concrete. The purpose of routine inspections is to find cracks, chips, delamination, spalling, salt build-up, rust streaks and deformation in the concrete.
  2. Detailed inspection – This is a thorough examination of a concrete structure that takes longer than a routine inspection. A detailed inspection requires the assessor to closely examine the concrete and use specialised tools to accurately determine the state of the structure. These inspections need to be carried out by trained engineers who can plan comprehensive repairs.
  3. Special inspection – These examinations are done in special circumstances or after unusual events. They are usually performed when a building is being extended vertically, when reinforced concrete pillars show signs of stress, when a foundation starts to collapse, after earthquakes or ground tremors, after a fire, after a flood and after accidents. Any of these circumstances or events will require an engineer to perform a special inspection, which looks at very specific aspects of a structure’s integrity.

These three inspections ensure that buildings and other load-bearing concrete structures remain in perfect condition. Routine inspections must be carried out regularly, white detailed and special inspections are more needs-based – they are carried out as and when necessary. All concrete inspections must be recorded and performed by trained engineers and contractors.

___

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.

The importance of post-cure concrete inspection

The importance of post-cure concrete inspection

All concrete structures and buildings need to be inspected on a regular basis to ensure that they are not damaged in any way. Construction inspections must be carried out before, during and after the concrete is poured to make sure that everything is in order and the quality of the structure is the best it can be.

One of the most important aspects of concrete inspection is regular check-ups after the concrete has cured. This post-cure concrete inspection will keep the structure in top condition for as long as the checks take place. Contractors and homeowners need to look for any cracks, defects and damage in their concrete buildings.

Concrete inspection should take place regularly

The first concrete inspection should be carried out as soon as the wooden formwork is stripped away. Contractors need to look for any defects in the structure and fix these before the concrete has fully cured. The entire curing process can take around 28 days. The earlier damage or defects are spotted, the easier they will be to repair.

Once the concrete has cured and hardened fully, contractors need to check the structure often until the building is sold or handed over to the new owners. Property owners need to continue these concrete inspections on a regular basis (at least once every three months) for as long as they own the building. 

Any new cracks that appear need to be repaired immediately; salt deposits on the surface of the concrete needs to be cleaned; concrete sweating needs to be addressed and signs of rust from exposed metal brackets and steel rebar need to be removed. Similarly, any mold or moss needs to be removed and the cause (usually humidity) needs to be addressed.

Running tests on post-cure concrete

If a contractor or homeowner is unsure of the grade of concrete used during the construction, they can run certain strength tests on the concrete. This is usually performed when a contractor thinks that the wrong grade of concrete has been used. A small cylinder of concrete is removed and the sample is put through various tests.

These include compressive strength tests, ultrasonic inspections and load-bearing tests. If the results find that a lower strength class of concrete has been used, then the contractors can either strengthen the concrete through reinforcement or replace it entirely, depending on the severity of the defects and damage.

These inspections and tests on post-cure concrete are vital for the condition of the structure. They ensure that a building is up to standards and that the concrete is always in good condition. Any defects or damage could threaten the structure and reduce the value of the building. Post-cure inspections should always be carried out for as long as a building stands.

___

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.

___

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.

The best ways to clean your concrete floors

Clean shoes on a concrete floor

Concrete floors are a popular feature of many modern homes in Tanzania. They are simple, clean and strong. Although concrete floors require little maintenance and are more durable than most other flooring materials, they still need to be cleaned often. To make your concrete floors last for decades, follow these tips on the best and easiest ways to clean and maintain them.

Sweep or mop your concrete floors

Using a broom or mop is the quickest and most efficient way to remove dirt and dust from the surface of your floors. A wet mop is perfect for removing dried soil and grass. It is also a good method of cleaning when it comes to small gaps and cracks – broom bristles can get into gaps while a wet mop will make the dirt stick to it.

Scrub your floors to avoid stains

Concrete is a porous substance – liquids can seep into the concrete floor if they are not cleaned soon. This means that concrete can be stained if you leave spilled drinks on the floor. Scrubbing the floor with a brush and some soapy water is the best way to clean spilled drinks. Dry the surface of the concrete floor once you’ve finished scrubbing to prevent further moisture build-up.

Polish the concrete floor regularly

Smooth concrete floors can be polished to give them a clean and shiny appearance. Buy some concrete floor polish and use a clean cloth to rub the polish into the floor using small circular motions. Alternatively, you can use a floor polishing machine – a large rotating padded disk that does the same job in far less time. Before polishing, vacuum the floor to remove any dust.

Use door mats to remove dirt

Place door mats at the entry to your house. The mats will pick up most of the soil, sand and grass that is stuck to the soles of shoes. They are a great way to prevent dirt from being brought inside and can save you a lot of time in having to clean the floors often.

Sealing the concrete can provide protection

Concrete floors do not need to be sealed, but doing so can provide more protection from soil and moisture. Concrete sealant is not a permanent solution – it does wear off over time, but it can be reapplied easily.

Follow these cleaning and maintenance tips to ensure that your concrete floors last many years and look great. The floors are a large part of your house, so clean them every day and look after them well.

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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.