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. 

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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 expose aggregate on concrete floors

How to expose aggregate on concrete floors

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

1. Brushing and washing

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

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

2. Using a surface retarder

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

3. Abrasive blasting

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

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

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

___

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

___

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

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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 salt finish a concrete floor

Salt finish concrete floors

A salt finish is a method of texturing a concrete floor for added grip and a different look. It works by sprinkling coarse rock salts on the surface of wet concrete and embedding them with a roller. Once the concrete dries and hardens, the salt crystals are then washed away with water to leave subtle dimples on the surface of the concrete.

Salt finishing gives a concrete surface added skid resistance and can also add a decorative appearance to floors and pavements. There are a few different ways to salt finish a concrete floor, but all of them require proper planning and execution in order to achieve the desired results.

The quality of the concrete and the salts will determine the finish achieved. The type of cement used will directly affect the performance and durability of the concrete surface, so we recommend using Tembo FastaPlus. Whether you want to salt finish a concrete floor or a driveway, you need to make sure that the ground is prepared and the concrete is poured properly before adding the salt crystals.

Prepare the floor for a salt finish

Once you have poured the concrete for the floor, pavement or driveway, take special care in the finishing process. Don’t overwork the surface as this can cause the concrete to shed moisture too quickly. Smooth the concrete surface and remove any excess concrete or water with a wooden float. This will give the surface of the concrete a fine and glossy finish.

Once the surface is smooth, leave the concrete to dry for a little bit. To test the concrete’s readiness for salting, press a finger onto the surface. If your finger can make a 5mm dent in the surface without leaving and concrete residue on your finger, then it is dry enough for the salt application.

Scatter the rock salt crystals over the concrete surface – the salt crystals should be between 3mm and 8mm in diameter. Try to evenly distribute the salt, using about 3kg of salt per 10 square metres. Press the salt into the concrete surface using a light roller or a trowel. The salt crystals should have half their diameter sticking out above the concrete surface. 

Remove the salt crystals

Leave the concrete to dry for 24 hours and then remove the salt with a broom and a hose pipe. The salt will dissolve when sprayed with water as salt is a soluble mineral. There is not enough water in concrete to completely dissolve the salt, that is why a hosepipe is needed.

When the salt is dissolved, it leaves small depressions in the concrete surface. These dimples give the surface extra grip and texture. It is advisable to apply a concrete sealer to the finished surface to give it a glossy look and to protect the new floor from wear and tear.

___

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 pour new concrete over an old concrete floor

New concrete floor

Old concrete floors can be replaced by new ones, simply by pouring freshly made concrete over the top. However, you will need to clean and prepare the old concrete surface first. If the old floor is badly damaged, you may have to break it up and lay a completely new floor. If the old floor is structurally sound and if fairly good condition, then new concrete can be poured on top.

Some repair work may require you to lay down some steel rebar to reinforce the new concrete floor. Make sure that you properly plan the pour so that you don’t waste time or money. Follow these steps to replace an old concrete floor with a new one by pouring fresh concrete over the top.

1. Clean old concrete surface

Before starting the repair job, you will need to clean the old floor. Sweep up any dust, dirt, sand or grass. Any dirt on the surface can affect the quality of the new floor. If the old concrete floor is a bit chipped, scrape it with a spade to dislodge any loose concrete flakes. Use a stiff-bristled broom to sweep up any concrete dust afterward. The floors can also be sprayed with a pressurised hose to loosen any stains or mud.

2. Make formworks

Pouring concrete over old floors still requires basic formwork to be made. Use timber and screws to make a wooden formwork that fits neatly around the old concrete surface. The form should extend above the existing concrete floor by the same thickness as the new floor.

Reinforce the form with wooden stakes or supports every one metre and make sure that the form is level. If there are any control joints on the old floor, mark their positions on the wooden form so that you can cut new ones on the new floor. If the concrete floor is surrounded by four walls, wooden forms will not be necessary (only at entry points such as doorways).

3. Place rebar

If you think that the floor needs reinforcement, cut some steel rebar to the right length. Look at the old floor and see where the cracks are located. The rebar can be placed across these areas to reinforce them. The rebar needs to be laid in a neat grid with 90-degree angles and fastened together with wire.

4. Saturate existing concrete surface with water

Before pouring the new concrete, hose down the existing floor to wet it thoroughly. This will prevent the existing floor from absorbing water from the new concrete. If the moisture inside the fresh concrete is absorbed by a dry floor, then the new concrete floor could crack and shrink.

5. Pour new concrete

Now it is finally time to pour the new concrete over the old floor. Tembo FastaPlus or SupaSet cement will be ideal for new concrete floors. Mix the cement with water, sand and crushed stone, according to the instructions on the back of the cement bag. Once the concrete is poured, tap the wooden forms to remove any trapped air inside the concrete. Run a metal pole through the new concrete mix to remove air bubbles and pack it tightly.

6. Finish new surface

Smooth the new concrete surface with a trowel and wooden float. In hot weather conditions, perform this smoothing process quickly as the concrete will dry quite fast. Once the surface no longer has any water on top, you can start to cut the new control joints at the locations you marked out earlier. This should be between four and twelve hours after pouring.

7. Leave to cure

Allow the new concrete floor to cure for about one week after pouring. Keep the surface damp by sprinkling water on it every few hours. If the concrete floor is exposed to sunlight or wind, place a plastic sheet over it to prevent rapid evaporation of moisture.

___

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.

Should you polish or resurface old concrete floors?

Polished old concrete floors in warehouse

Concrete floors are perfect for homes – they are easy to clean and require little maintenance. Sometimes, homeowners want to revamp their concrete floors after many years of use. What is the best way to give your concrete floors a fresh look? Polishing and resurfacing are the two best options for renewing old concrete floors.

Depending on your situation, one of these processes may be better than the other. It all depends on the condition of the concrete, the amount of use the floor will endure and what look you want to achieve when the job is done.

What is the condition of the concrete floors?

Most of the time, old concrete floors can simply be polished to renew their condition. Polishing should be done on smooth floors, not grainy or brushed concrete. The process is the quickest and easiest way to revive your old floors.

However, if the floor has cracks, unsightly patchwork or spalls (holes created by wear and tear), then resurfacing might be the only option. This means covering the damaged floor with a decorative concrete overlay, such as false tiles, or adding a new layer of concrete on the surface of the old floor.

How much use will the floor have to endure?

Polished concrete floors are extremely tough and durable. They are stronger and more resilient than concrete overlays. In high-traffic areas, such as doorways and the kitchen, polishing the old concrete floors will keep them in good shape.

Polished floors are also easier to maintain because they don’t require sealing. Resurfaced concrete floors should be protected by a sealer once the concrete has cured. This will help the resurfaced floor to endure foot traffic and abrasion more easily. Highly-used areas of your floor should be polished and cleaned regularly to prevent dirt from damaging the surface.

What look do you want to achieve?

If the look of your floors is important to you, then it may affect your decision to polish or resurface. By resurfacing the concrete, you can change the colour or appearance of your concrete floors. It will give you an opportunity to dye the floors a different colour, or use stenciled patterns to stamp the floor.

Polishing is more limited in that you cannot change the colour or decorate the concrete floor. If you are happy with the appearance of the floor, then polishing will renew its condition with little fuss and little money. Polishing is a cheap way to revive old concrete floors and give them a new shine.

Should you polish or resurface old floors?

The table below outlines the best solution for renewing concrete floors:

Floor variablesPolishResurface
The floor is in good condition, with no major damageYesNo
The floor has major flaws requiring extensive repairsNoYes
The floor is in a high-traffic area of the houseYesYes
You want the floor to have a smooth, shiny surfaceYesNo
You want the floor to have a textured or patterned finishNoYes
You want to minimise maintenance and costsYesNo
You want to colour your floor with stains and dyesNoYes

___

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.

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.

___

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.

How to make concrete floors

Large warehouse with concrete floors

Concrete floors are durable and easy to maintain. They are a popular choice in modern homes as they keep costs down and are easy to clean. The affordability of concrete floors and the fact that you can make them yourself mean they are suited to Tanzanian homes.

Items needed to make concrete floors

Steps to make your own concrete floors

  1. Using the string and the chalk, mark the desired floor height on the walls around the room. This will be your fill line.
  2. Pour a layer of crushed stone on the floor, about 2cm lower than the fill line. Using the tamper or a steel plate, stamp the stones down to compact them. Make sure they are level.
  3. Pour a layer of sand over the crushed stones and pat it flat with a trowel or shovel. The sand should be about 1cm below the fill line.
  4. Lay a plastic sheet on top of the sand and tape the edges to the side of the wall along the fill line.
  5. Mix your Tembo cement with water in a wheelbarrow. FastaPlus works best as it is durable and can support weight. Follow the instructions on the bag.
  6. Starting at the wall furthest from the door, place a layer of concrete on the plastic sheet with a shovel.
  7. Use a straight plank to scrape and level the concrete along the fill line, covering the plastic sheet and smoothing the concrete along the base of the walls.
  8. Use a trowel and extra concrete to fill in any gaps or indentations. Use a plastering trowel or a float to smooth the concrete floor nicely.
  9. Allow the concrete to cure for seven days, keeping it damp the entire 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 the Mbeya Region at Songwe 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.