Synthetic fibres can increase the durability of concrete

Synthetic fibres can increase the durability of concrete

Contractors sometimes add synthetic fibres to their concrete mix. These fibres of man-made polymers are specifically engineered to withstand the long-term alkaline environment within a concrete mix. They are used to minimise cracking, lower the permeability of the concrete and increase the strength of the structure.

They act as a secondary reinforcement element; the primary element being steel rebar. These synthetic fibres benefit both early-age and hardened concrete in a number of ways. In early-age concrete, volume changes can occur once the concrete is poured and begins to set. This can cause microcracks to form if the volume changes too much. The synthetic fibres block these cracks and act as an internal support system.

Synthetic fibres improve the strength of hardened concrete

In hardened concrete, synthetic fibres lower the permeability to water and moisture. This prolongs the durability of the structure and prevents moisture damage. The fibres also improve the impact and abrasion resistance of hardened concrete by holding the particles together, making the structure stronger. The fibres have great shock absorbing characteristics.

When normal concrete is compressed, it tends to shatter at the first crack that develops. However, by adding synthetic fibres, this tendency to shatter is eliminated. Cracks will still form under extreme compression, but the structure will still hold together somewhat due to the binding properties of the fibres and concrete particles.

Synthetic fibres as secondary reinforcement

Certain concrete structures may need additional reinforcement for extra load-bearing capacity. However, steel rebar may add to the weight and expense of the structure. In these cases, synthetic fibres can be used as a means to provide additional support without adding too much weight to the concrete.

Synthetic fibres which meet certain criteria can be used as non-structural secondary reinforcement. These fibres should have documentation that confirms their ability to hold concrete together after cracking. Synthetic fibres can also be used with other admixtures and cement chemistries for additional strength and durability benefits.

Guidelines for using synthetic fibres in concrete

Synthetic fibres should be used in concrete for:

  • Reduction of concrete cracking as a result of shrinkage.
  • Non-structural secondary reinforcement.
  • Greater impact, abrasion and shatter resistance.
  • Internal support and cohesiveness.
  • Lower water and moisture permeability.

Synthetic fibres should not be used for:

  • The control of cracking as a result of external forces.
  • Replacement of steel rebar, where this is a necessity.
  • Decreasing the thickness of a slab.
  • The elimination of curling in thin slabs.
  • Reducing the size of support columns.
  • Thinning of bonded or unbonded overlay sections.

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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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The eight types of construction company

The eight types of construction company

There are many different types of construction company. Not all contractors specialise in the same fields and not all companies do the same construction work. Depending on the type of work they do, construction companies can be classified into the following eight types:

1. General contractors

A general contractor provides all of the labour, equipment, materials and services needed for the construction of the project. General contractors often hire subcontractors to perform part or all of the construction work on a project – especially those subcontractors that are specialists in their field, such as plumbers, electricians and roof tilers.

2. Owner-builder

An owner-builder takes responsibility for domestic building work done on their own land. They are legally responsible for the project from beginning to end. Owner-builders construct buildings for themselves, to sell once it is finished or to rent out and manage. Many owner-builders also act as general contractors as a secondary business.

3. Small renovation contractor

Small renovation contracts usually work on jobs with small budgets or that don’t require large amounts of capital. They do work that does not need a lot of estimations or require a large construction organisation. They usually do home renovations and alterations, as well as small commercial and office work. They often have their offices at home and do their paperwork in the evenings.

4.  Real estate developer

A real estate developer is a type of owner-builder who constructs property developments for personal ownership. However, they also build to sell before or after finishing a project. This category includes one- and two-family home builders. Most real estate developers will buy an empty plot of land and construct several independent homes for maximum resale value.

5. Package builders

Package builders both design and construct buildings. Their services often include buying the land as well as financing the project. Package builders can usually show prospective clients examples of similar buildings they have completed for previous clients. They often employ their own architects and engineers, as well as construction workers.

6. Professional construction manager

A professional construction manager is an individual or company who does all the required work on a building project, on behalf of or as an agent of an owner. The construction manager often supplies all the necessary personnel required. The management company outsources the construction work in the name of the owner and does all the necessary administration, supervision, safety regulation, requisitioning, paying of subcontractors, payroll reports and other work on the owner’s behalf, for a fee.

7. Sponsor builder

Sponsor builders often work in the field of government-aided or subsidised building, particularly in the housing sector. A sponsor-builder may be responsible for the planning design, construction, rental, management and maintenance of a project. A sponsor steers a project through the government processing and design stages. They also hire attorneys to deal with the various financial institutions, government agencies and real estate consultants.

8. Program manager

Sometimes, general contractors or construction managers broaden their services by offering program management. These services can include the demolition of existing buildings on the site, the acquisition of a new site, providing financial analyses of new buildings and the hiring of an architect on behalf of the owner. A program manager will also supervise all services, advertise for and receive bids from contractors for the new work, obtain tenants and help administer and manage the entire project.

These eight construction companies have various fields of expertise and specialise in different aspects of construction. When building a structure, it is important to first find the correct construction company for your needs and requirements, based on the services they offer and what type of company they are.

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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 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.

___

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

___

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

What is exposed aggregate concrete

What is exposed aggregate concrete

Exposed aggregate concrete serves two purposes; it is both decorative and functional. It is a term used to describe a concrete surface, such as a floor, path, pavement or parking lot, that has exposed gravel. This method is used to create flat surfaces that not only look good, but they also provide extra grip in wet conditions.

Exposed aggregate concrete is made by removing the top layer of cement and fine aggregate from freshly-poured concrete. This leaves the large aggregate particles (crushed stone or gravel) exposed and sticking out the top of the surface slightly. It is a durable and skid-resistant surface that is often used to make driveways, paths, pool decks and floors safer.

Methods for creating exposed aggregate surfaces

There are many ways to create these types of surfaces, but contractors generally use four methods.

  1. Standard – The standard way to create exposed aggregate surfaces is by mixing a normal batch of concrete; cement, sand, water and crushed stone. The concrete is then poured and left for an hour or so to harden slightly. A broom is then used to vigorously sweep the surface, removing the fine concrete particles and leaving behind the exposed gravel and stone particles.
  2. Seeded – This method involves placing the gravel or crushed stone, by hand, into the surface of freshly-poured concrete. It is similar to planting seeds in the ground, except that just the surface of the stone is left sticking out the top of the concrete.
  3. Topping – Also known as a concrete overlay, this method is used to upgrade and existing concrete surface into a slip-resistant one. A fresh concrete batch is mixed and poured thinly on top of an old floor or path. The thin layer of concrete leaves the thicker stones exposed along the surface.
  4. Polished – This method is often used inside homes and is more decorative than functional. Instead of leaving the aggregate exposed with a textured surface, a grinder or sander is used to flatten the surface and make it level. Several layers of clear coat sealer are applied to create a shiny, polished surface.

As a general rule, the exposed gravel should always be at least two-thirds embedded in the concrete. This will prevent the stones from lifting and being removed from the surface, which would leave holes and large pits in the concrete. These pits can then collect dirt, water and soil, which can affect the durability of the floor.

Benefits of using exposed aggregate concrete surfaces

There are a number of reasons why people choose to use exposed aggregate surfaces in their homes and gardens. Firstly, it can look really nice if you use stones of various shapes and colours. Some homeowners like to match the colour of the exposed stones with the rest of their furniture. This makes it a customisable and aesthetic feature of a house.

Exposed aggregate surfaces are also very durable. They have the structural integrity of concrete and can last for 40 years or more. These surfaces are also highly-resistant to wear and tear and heavy traffic use. They can also handle exposure to the elements really well – sun, rain and hail have little impact on the strength and durability of these surfaces.

As with concrete floors, exposed aggregate surfaces require little maintenance besides sweeping and hosing with water. This makes them a cost-effective solution for floors and driveways. They don’t cost too much to install and they are certainly not expensive to maintain.

The main benefit, however, is the skid-resistance and added grip of the exposed aggregates. These surfaces are useful in wet conditions or around swimming pools. They ensure the safety of users, preventing slips and falls which could lead to serious injuries. Exposed aggregate concrete surfaces are safer than many other flooring materials, especially when wet.

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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 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.

___

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 is concrete bleeding?

What is concrete bleeding?

Concrete bleeding is a problem that can affect any batch of concrete that has been improperly measured and mixed. It is the movement of water to the surface of the concrete after it has been poured. Water collects on the surface of a concrete slab or structure when the water-to-cement ratio of the mix is too high (when too much water has been added to the batch). 

Bad proportioning of materials in a concrete batch is the main cause of bleeding. Too much water causes the concrete to segregate – a phenomenon where the heavy aggregates sink to the bottom of the mix, leaving the cement, sand and water at the surface of the structure. The water then seeps to the surface of the slab or structure, which creates big problems on the resultant integrity of the concrete.

When the water travels to the surface of the structure, it carries the fine particles of cement with it. This leaves a deficiency of cement within the rest of the structure. Since cement is the main binding material, the rest of the structure dries without much bonding between materials. Bleeding causes a weak, crumbly and dry concrete structure that cannot support any weight.

Bleeding affects the workability of concrete

There are two categories of concrete bleeding; normal and excessive bleeding. These are determined by the amount of water lost through the surface of the concrete structure. Both normal and excessive bleeding can affect the final quality of the concrete and the overall durability of the structure.

Normal bleeding is that which often occurs in all concrete projects. When you see freshly-poured concrete, it will often have a very thin layer of water on its surface. This is nothing to worry about and can actually enhance the workability of the mixture. The improvement in workability makes it easier to pour and work with before it sets. It also gives the concrete a smooth finish.

Excessive bleeding is an abnormal amount of water loss through the surface of the concrete. The mixture is usually too wet before it is poured. Contractors should keep an eye on their concrete batch and add more cement or dry aggregate if they think the mixture is too runny. Excessive bleeding leads to a high loss of water and a dry, brittle concrete structure.

Concrete that has suffered from excessive bleeding may also have large voids in the centre of the structure where heavy aggregates have moved the fine particles out of their way as they sink. This creates air bubbles and empty pockets that can severely affect the strength and durability of the concrete.

The best way to prevent concrete bleeding is to use the required amount of water, as printed on the bag of cement. Contractors can also carry out a slump test to check the mixture has the correct ratio of dry to wet ingredients. Bleeding is a normal occurrence with concrete, but excessive bleeding creates long-term problems that cannot be easily repaired.

___

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 having a schedule for a construction project

The importance of having a schedule for a construction project

Construction projects are delicate operations that need to run on time in order to stay within the allocated budget. As soon as a project is delayed, it costs the contractors and building owners more money. Having a strict schedule is important as it keeps the project on time and allows all workers to know when to expect certain deliveries and deadlines.

A schedule is the process of assigning tasks, activities, milestones and deliveries to a construction project – basically setting deadlines that everyone will work towards meeting. The schedule will be used by all construction teams on the project, as well as the suppliers, to finish the building on time. It outlines the pace of work and how the tasks are supposed to be executed, but it also outlines how the team should deal with changes in the plan and delays. 

Why a construction schedule is important

The schedule is a vital planning document that outlines the following points:

  • It assigns dates and deadlines for the project’s activities.
  • Contractors can see whether these deadlines are obtainable or not and whether delays can be avoided.
  • The schedule allows contractors to estimate preliminary costs or tender bid estimates.
  • It can be used to plan the necessary resources (such as equipment, materials and labour) to meet the work tasks and deadlines.
  • The schedule provides a sequence of tasks so the project manager and all teams know what they need to be working on and what tasks they need to be prepared for.
  • It can improve the safety performance of a project by sequencing activities to ensure maximum protection for contractors.
  • It enables teams to set their own goals and work towards achieving these.
  • It outlines how delays can be dealt with in the smoothest and most efficient manner.
  • It eliminates problems of production bottlenecks, where many deadlines fall on the same day.
  • The schedule ensures that the project is completed at the soonest possible date.
  • It gives the building owners a target date by which their building should be ready for use.
  • It can be used post-completion to evaluate the contractors’ performances and to assign responsibility for any delays or overspending.

The building schedule is one of the most important documents for project managers, contractors and building owners. It keeps a project running on time and within budget. However, the schedule needs to be realistic and the estimations need to be achievable in order for it to be a valuable resource for the project.

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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 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.

___

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 four phases of project management

The four phases of project management

All construction projects require input from a team of various experts. Architects, contractors, project managers and suppliers have the most important roles to play in the creation of a new building. The project manager is the link between all of these teams. It is their job to ensure the project runs smoothly, on time and within budget.

The project manager needs to be organised and keep an eye on all aspects of the building’s progress. To do this, a project manager will need to use a phased process. There are four phases of project management that will ensure the building is completed efficiently and to a high quality. 

1. Defining and organising the project

The first phase of project management is to define the task at hand – what are the objectives of the project and whose expertise will be needed to help you complete these objectives successfully. Identify the competing demands of each team working on the construction site and plan how to overcome these conflicts while keeping all teams satisfied.

Organising the project requires the manager to define the roles and responsibilities of each team. The project manager should create a detailed estimate of the costs and timeframe in which the building should be completed. This organising phase will help to keep the project on schedule for its entire duration.

2. Planning the project

The planning phase of project management is based on the previous step. In the planning phase, the project manager will assemble a team of contractors and suppliers and assign tasks to individuals. The budget can be adjusted if necessary once the plans start to take shape. The project manager must also finalise the deadlines for the construction project during the planning stage.

A communications plan is also required, so the project manager can draw one up and distribute it to each team. This will ensure that all teams know who to communicate with and what the appropriate channels of communication will be. This is the last chance to make any final changes to the plan before the actual construction process begins.

3. Executing the construction project

This is the main phase of a project – the period where the construction takes place. Each team is required to monitor and control their own costs according to the budget set out in the previous step. They must also work to meet the deadlines assigned to the project. The project manager must now oversee all the teams and ensure that everything is running smoothly.

If the project falls behind schedule or is starting to creep over the budget, the project manager must take the necessary steps to fix the situation. Remember that time is money; the longer a project takes, the more it will cost. The project manager must keep strict control over deadlines but still ensure that the quality standards are met. This phase is the most stressful for all teams involved.

4. Finishing the project

At the end of the construction process, when the last interior fittings are being installed and the walls are being painted, the project manager must evaluate the performance of all teams involved. The project manager can use a variety of documents and records to analyse the construction process. This phase will also help the manager to decide whether they are satisfied with the teams’ performances and whether or not to use them again for projects in the future.

These four phases of project management will ensure that a construction job runs on time and within the allocated budget. They will help to align the goals of the various teams and the project manager. The overall result is a well-built structure that is completed to a high degree of quality.

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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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Improving the earthquake resistance of small buildings

Improving the earthquake resistance of small buildings

Tanzania is prone to earthquakes and earth tremors. The country has experienced five serious earthquakes since the year 2000. These natural disasters often result in widespread damage and even death. Small buildings and old structures are most at risk when an earthquake strikes, so it is important to improve the resistance of this infrastructure.

Small buildings can be made safer and stronger by taking certain precautions throughout the construction process. The earthquake resistance of buildings has improved dramatically over the past few years. Tanzanian architects and contractors can use some of these tips to make their small buildings more resistant to ground tremors.

Building plans should be symmetrical

Architects need to be aware that symmetrical buildings are more stable and safer during earthquakes than asymmetrical structures. Simple, square or rectangular building plans are more sturdy than ornate designs. Avoid L-shaped and T-shaped houses as these can crack at the corners during an earth tremor. Rectangular buildings should not have a length more than twice the width – this will maximise the earthquake resistance.

Site selection is important

Contractors should avoid building small structures on unstable ground, especially near embankments that are prone to collapse during earthquakes. Sloping or uneven ground should be excavated and graded before any foundations are laid. Similarly, wet soils near river banks and wetlands can also shift and resettle during ground tremors, which could affect the foundations of small structures.

Solid foundations are key

One of the biggest factors affecting earthquake resistance is solid building foundations. The width of a small building’s foundations should be 75cm or more for single-storey houses and 90cm or more for double-storey homes. The depth of the building foundations should be 100cm or more in soft soil and sand, or 50cm in rocky ground. Before the foundations are laid, remove any loose materials from the trenches and compact the ground as much as possible. After the foundations are laid, back-fill them properly and compact once again.

Choose high-quality building materials

The best building materials are high-quality ones that come from reputable companies. LafargeHolcim Tanzania makes a variety of cement products that are strong and durable. Use properly-burnt bricks or well-formed concrete blocks. Brush the top and bottom faces of the bricks and blocks before laying to ensure a clean bond with the cement mortar. 

Use river sand for the mortar and concrete as it is the cleanest and best fine aggregate available. Avoid using a coarse aggregate over 30mm in diameter. Aggregates should be well-graded and angular for the best bond with cement. Dry mix the cement and aggregates thoroughly before adding the water. The length of brick walls should not exceed six metres in small homes – use intersecting partition walls to separate long exterior walls for maximum safety during a ground tremor.

Doors and windows can affect stability

Walls with too many doors and window openings are more unstable than solid walls. This means that having too many windows and doors on a wall will make it prone to early collapse during an earthquake. The total width of all the openings should not exceed one-third of the length of the wall. Avoid building doors at the end of a wall – they should be at least 50cm away from the edge of a wall.

Building a solid roof is important

In structures with a roof span of over six metres, use proper wooden trusses instead of rafters. These are far stronger and more durable than simple rafters. Small buildings with four-sided sloping roofs are stronger than two-sided sloping roofs. This is because the gable walls are prone to cracking and collapsing during an earthquake.

Retrofitting ensures stability in small buildings

Retrofitting is the process of building a structure such that all elements act as integral units of stability. It is the best way to achieve the maximum safety of a building. Examples include:

  • Anchor roof trusses to the walls with metal brackets.
  • Strengthen gable walls by inserting a sloping belt.
  • Strengthen corners of the building with seismic belts.
  • Anchor floor joists to the walls with brackets.
  • Provide vertical reinforcement between different floors of a building.
  • Encase wall openings with reinforcements.

These tips will help architects and contractors to make their buildings more resistant to seismic activity. Earthquakes and ground tremors often result in building damage or total collapse – neither of which are desirable for the safety of the people living inside the structures.

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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.