Preparing for a Topping Slab

A concrete topping gives a finished floor surface a new look and increases its strength.  Ideally, concrete contractors will design the overlay top to provide a dense, abrasion-resistant floor surface. In addition, a concrete topping serves a multi-purpose use, which include supporting the traffic load in parking facilities or other heavy traffic areas.

What is the Purpose of the topping slab?

  • T\to provide the slab with adequate waterproofing
  • to ensure abrasion resistance to the underlying slab
  • to dd a wearing course that supports the load coming on the concrete surface
  • T\to ensure a level floor surface
  • to develop an additional superimposed load-bearing capacity

Different types of concrete topping slab:

1. unbounded topping slab

This system is where the topping slab is not bonded to the underlying concrete slab. The unbounded topping slab thickness may influence the final floor elevation and interfere with other service requirements like doorway clearances. In addition, if the cracks in the base slab are repaired in the process, they may eventually reflect through the partially bonded overlay. This reflective cracking could be reduced using thicker overlays.

The unbounded concrete topping is used for a contaminated slab and for slabs where bonding is impossible. This  topping is also used where it is preferable not to bond the topping to the base course. Therefore, the two courses can move independently or move at a later point in time.

2. bonded topping slab

In the bonded system, the topping adheres to the underlying concrete slab. Therefore, the bonded topping slab is used for both light-duty slabs in commercial applications and heavy-duty slabs in industrial applications. The application area largely depends on the traffic loads\.

The base slab surface should be rough and feature an open pore finish. In addition, the base slab should be free of any substances that could interfere with the bond of the topping to the base slab. Note that the topping can be placed before hardening the base concrete slab or after the base slab has set.

Topping a light-duty slab features a concrete mixture similar to that for a concrete slab. You will require multiple passes for the heavy-duty slab, a hard-steel trowel finish, and higher strength compared to the base slab.

For bonded andunbounded concrete topping slabs, the strength of concrete is governed by the function of the slab. You can use reinforcements such as deformed steel bars, welded wire fabric or fibre. Thereinforcement selected is placed in the mini concrete topping to reduce the width of the shrinkage cracks.

Conclusion

Adding a topping slab is becoming a widespread redevelopment practice since it is cost-effective and aesthetically pleasing compared to other slabs. Generally, the topping slab is more sustainable and high performing, while it provides a more refined surface finish. Talk to a professional concrete delivery company to ensure good quality concrete for your topping slab.

Subgrades and subbases for slabs – suitable materials and techniques that provide a solid foundation

The soil support system beneath your concrete slab is critical to a successful job. Brisbane’s experienced concrete suppliers understand that a well-compacted subgrade and subbase is the key to a solid concrete slab. Therefore, if you place concrete on an unstable soil support system, you will either waste the concrete or end up with a thin floor. Placing concrete on an inconsistent foundation results in cracking because the ground is not solid and stable.

What is a subbase / subgrade for slabs?

The subgrade is the soil that is usually compacted when preparing for slab installation. Thus, you find this soil at the bottom of the slab system. The subgrade may refer to the native soil or the improved soil delivered from a different source.

The subbase refers to the layer placed on top of the subgrade. Thus, the subbase features an easy- to-trim granular fill that remains stable and supports the slab. Therefore, the subbase and subgrade comprise the soil-support system for the slab. So, how do you ensure suitable materials and techniques for a solid foundation?

Here are essential considerations to bear in mind when working on subgrade or subbase.

  • Slits cannot be compacted in thick layers. Only granular soils can compact appropriately in thick layers. However, note that slits can be compressed at the optimum moisture content.
  • Soiling soil can expand and contract with moisture variations. The contraction and expansion of swelling soils affect the slab integrity. Therefore, avoid using swelling soils when working on subbase and subgrade.
  • Talk to Brisbane concrete suppliers for the right chemicals and materials for controlling the subbase and subgrade.
  • The subbase materials consist of naturally occurring coarse-grained soil or blended and processed soils.
  • Where possible, avoid the use of materials with more than 15% fines.
  • The subgrade and subbase thickness depends on the type of materials, compaction equipment, and construction method. However, the bottom line is that the subgrade should be thick enough to withstand the load on it.

What are the advantages of adding the subbase /subgrade layer?

  • The subbase or subgrade layers provide strength and support to the overlying pavement.
  • They provide proper drainage and ensure adequate frost protection
  • A compact subbase and subgrade prevents settlement to the pavement and the slab on a grade.
  • Subbase and subgrade compaction keeps the construction workers out of the mud and creates a workable surface before placing the concrete slab.
  • Overall, a well-laid subbase and subgrade reduces construction costs.

Subgrade soil is classified under four broad categories.

  1. Gravel—a coarse material featuring little or no fines and hence provides cohesion of materials.
  2. Moorum — the product of decomposition and weathering or rocks, similar to gravel.
  3. Silts— finer than sand and brighter in colour compared to clay, while they exhibit little cohesion.
  4. Clay—a type of soil that exhibits stickiness and features high strength when dry.

The types of subbase for flooring come in four categories:

  1. Cementitious— a lean concrete with a lower cement content that binds stone aggregate and sand.
  2. Granular—a popular alternative for cementitious
  3. Hill earth—a unique material used as a subgrade.
  4. Polyurethane foam insulation— a unique situation subbase material encountered in cold storage applications.

Conclusion

We have looked at the different subgrade and subbase materials. Now you know to ensure your site is compact before laying concrete. Talk to Reocrete for concrete delivery. We are theleading Brisbane concrete suppliers.

Using admixtures to get concrete to do what you want

An admixture is an ingredient used in concrete preparation, modifying the premixed concrete to enhance specific properties like concrete workability, durability and strength. The admixtures added to concrete depend on theparticular application.

Admixtures play different roles:

  • Accelerating concrete setting time
  • Reducing the segregation and water to cement ratio
  • Improving pumpability and accelerate the rate of strength development

You will need to specify to yourBrisbane concrete suppliers the areas you intend to apply the concrete so the right admixture is used.

What are the Different Admixtures?

 

We have seen that the choice of an admixture depends on the application area and its purpose. Now we will look at some of the different admixtures available on the market today.

1.  Water Reducing Admixtures

As you can tell from the name, water-reducing admixtures usually reduce water to create a concrete mixture. As a result, using a water-reducing admixture means you cut the amount of water you require to prepare the concrete. Consequently, using a water-reducing admixture means increased strength and workability along witheasier placement. Therefore, reducing the water to cement ratio in concrete preparation is an essential factor in making durable and high-quality concrete.

Water-reducing admixtures fall into three group’s namely, low, medium and high range. Determining the correct category for your application will depend on the percentage of water reduction desired.

2. Retarding Admixtures

Retarding admixtures slow the rate of concrete setting. By restricting the initial setting time, the concrete mixture stays in the fresh mix longer before hardening. The use of retarding admixtures is appropriate for various uses. The particular cases for retarding admixtures include:

  • Complex concrete placement or grouting
  • A specific architectural surface finish
  • Compensating for the accelerating effect of high temperature on the initial set
  • Prevention of cold joint formation in successive lifts

Organic and inorganic materials can aid the construction of the retarding admixtures.

3. Accelerating Admixtures

Accelerating admixtures are those admixtures when added to concrete, mortar or paste increase the rate of hydration of hydraulic cement and shorten the setting time while increasing the rate of early strength development.

Accelerating admixtures are more effective if applied under low temperature. Therefore, they serve best with superplasticisers where early age strength is required, mainly under lower temperatures.

4. Air-entraining admixtures

Air-entraining admixtures facilitate the development of microscopic air bubbles within the concrete during mixing. They add to thefreeze-thaw durability of concrete and increase its resistance to scaling caused by the deicing chemicals.

Generally, air-entraining admixtures are used in a cold-weather climatewhen the water within the concrete capillary poresfreeze and expand. If the concrete is critically saturated, the expansion of ice will exert pressure within the hardened concrete, causing cracking.

Usingair-entraining admixtures stops the formation of bubbles by stabilising the microscopic bubbles created when preparing concrete. Air-entraining admixtures reduce the surface tension of mixing water and promote the development of tiny bubbles. Stabilising the bubbles by forming a sturdy shell hinders the coalescence of bubbles and promotes the attraction to cement and aggregate particles.

Conclusion

Using admixtures imparts early strength in concrete. In addition, admixtures can improve the quality of concretewith proper application. Talk to approved concrete suppliers near you for the best concrete prices in Brisbane and the delivery of quality concrete suitable for your application.

What is the difference between polished concrete and decorative concrete surfaces?

One of the top flooring trends for commercial and residential spaces is concrete floors. Premixed concrete suppliers Brisbane provide a whole range of concrete types for both commercial or residential flooring. Popular choices available today are polished concrete and decorative concrete surfaces. What is the difference between polished concrete and decorative concrete?

Polished concrete

Polished concrete is a versatile material featuring stunning aggregates, quartz, and unique colours to create a sense of sophistication in residential and commercial spaces. Polished concrete features an easily customizable appearance, with a reflective surface that creates an evocative quality under certain types of lighting.

Most Australian builders prefer polished concrete flooring for interior spaces.  However, you will see polished concrete floors in different exterior spaces as well, including patio floors and even exterior panels.

Concrete suppliers use a variety of methods to create polished concrete. One approach is the “grind and seal” method, which uses a penetrating sealer to create a reflective surface. Mechanically polished concrete is popular in commercial projects since it is durable and suitable for high-traffic locations.

Advantages of polished concrete

As with different flooring types, polished concrete has of advantages. Here is an overview of the top benefits of choosing polished concrete:

· Polished concrete is solid and resilient

Concrete contractors in Queensland Brisbane choose polished concrete for surfaces experiencing hefty foot traffic. Professionally-mixed polished concrete is difficult to damage, and it is nearly impossible to chip or scratch.

· Longer life-span

When properly installed, polished concretecan last for decades. Its lifespan surpasses that of different floor coverings, making it is a money-saving flooring option.

· Easy to maintain

Polished concrete floors entail an easy maintenance procedure. Regular dusting, mopping, and broom sweeping will ensure that there no stains on your polished concrete floor.

Decorative Concrete

Decorative concrete can beimbued with different looks and styles to formeye-catching appeal. A wide range of finishes, colours, and design elements create a visually impressive look in residential or commercial spaces. Therefore, using decorative concrete for residential or commercial areas provides builders with arange of options to beautify their floors.

If you are interested in using decorative concrete, talk to professional concrete suppliers Brisbane for customized decorative concrete suitable for floors, walls, paths, and even driveways. Different options for decorative concrete surfaces include textured concrete, stamped concrete, and colored concrete.

These are two most popular concrete options available today in concrete. While there are tons of options to choose from, you may become confused when selecting the appropriate one for your particular surface. Here are some essential factors to bear in mind when it comes to the choice of concrete.

Advantages of decorative concrete floors

· Wide range of choices and aesthetics

You will not experience a lack of choices when opting for decorative concrete for an interior space, an exterior space, or landscaping. Decorative concrete floors feature a wide range of colours, patterns, and textures.

· Ease of installation

Another top reason to use decorative concrete is ease of installation. Overall, decorative concrete features a far less labour-intense installation process.

· Durability

Decorative concrete is easy to maintain and lasts a long time. However, you need to engage qualified concrete contractors to ensure correct procedures are followed when installing the decorative concrete.

Conclusion

We have covered the popular choices available today when it comes to the selection of concrete floors. Talk to experienced concrete suppliers for suitable premixed concrete. Reocrete is a professional concrete delivery company serving commercial and residential customers. Reach out to us for premiere polished or decorative concrete.