Understanding Slump

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Slump refers to the measure of concrete fluidity and consistency, and it shows the flow and workability of premixed concrete. When mixing concrete, figuring out slump quality should be a priority because it directly affects the ease or difficulty of working with the concrete. It is essential to clearly understand slump, including what it is, how to test it, how to interpret the results, and many other facts. This article will help you learn more about the slump of concrete.

Slump Test

The test is done using a slump cone, usually in the shape of a conical frustum. The cone is open-ended and has handles attached to both sides of it. The cone has a diameter of around 3.6 inches at the top and 7.8 inches at the bottom. The height is about 12.1 inches. At the start of the test, the cone is placed on a hard surface that is not absorbent. Fresh mini concrete is put into the cone in three stages.

When each layer is added, it is tamped about 25 times with a long bullet-nosed metal rod. In stage three, the concrete is levelled off at the top of the mould. Then the mould is carefully lifted vertically to avoid disturbance of the concrete cone, and the concrete subsides. The distance from the top of the slump cone to the top of the slumped concrete is measured.

Interpretation of Slump Test Results

The profile of the slumped concrete determines the shape it is considered in the results of the test. The categories of the results are a true slump, collapse slump, or shear slump. An excessively wet mix is called a collapsed slump. For the shear slump, the top portion of the concrete shears off and slips towards the sides.

A 0-25 mm slump is considered very dry and used in construction projects such as road construction. Concrete with a slump of around 10-39 mm has low workability and is used for light reinforced foundations. A 50-91 mm slump has medium workability and is used as typical reinforced concrete. High workability concrete has a slump of above 100. This type is used to fill tight spaces for reinforcements and concrete that needs to flow long distances.

What Happens If the Concrete Slump Is Too High or Too Low?

If the slump is too high or too low, it means that the concrete has low workability. The workability makes it hard to handle. When the specified range is exceeded, shrinkage may occur. The concrete slump should be maintained at a workable range depending on the type of project you are doing.

Conclusion

The slump of the concrete is significant when using concrete during construction. It is essential to understand concrete slump clearly so that no mistakes are made when completing a construction project. This information can also help you make your projects more durable.

What If the Colour of Exposed Concrete Does Not Turn Out or Match My Existing Slab?

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Exposed concrete is ideal for outdoor use, and it makes a perfect choice for driveways and areas requiring additional grip. Are you planning to install exposed concrete on your driveway or porch? When adding exposed concrete to an existing concrete slab, a common question is what if the exposed concrete does not match the colour of my existing slab? Here are some ways you can deal with this concern.

What You Should Know About the Colour of Exposed Concrete Slabs

The colour of exposed concrete not matching the colour of an existing concrete slab is something every contractor has seen. If the contractor installed a section of the concrete slab years ago, some of the coloursmight have faded. Also,some areas of the existing concrete slab might be worn through the sealer. Because of general wear and tear, there will likely be some colour variations.

The materials used for manufacturing exposed concrete are also subject to natural variations of colour, texture, size, and even shape. Some of these variations are common from one batch to another. Customers might order and install exposed concrete to a section of the concrete slab. Weeks later, the customer comes back to order more exposed concrete to complete the remaining areas. Between the two batches, the colour of the exposed concrete might be slightly different.

What to Do When Colour of Exposed Concrete Does Not Match Existing Slab

If the colour of your new concrete does not match the existing slab, here are a few options you have to fix the issue.

Applying an Overlay

An overlay on the existing concrete slab can help make the different colours match more closely. An exposed concrete overlay refers to the thin cement-based product that goes over the existing concrete slab. The concrete overlay is applied for decorative purpose or when repairing a section of the concrete slab. A concrete overlay can be used as a thin finish or up to ¾ inches. The depth depends on the desired finish and the extent of damage on the concrete surface.

Restain and Seal

Restaining a concrete slab is a great way to add colour to the otherwise dull surface. The process may take up to two days, and you should hire an expert. Ensure the concrete slab is cleaned before applying the concrete stain. After applying the concrete stain, ensure you clean up and neutralize the stain. Finally, seal the concrete to provide long-term protection. Make sure to choose the concrete stain carefully to match it to the exposed concrete as closely as possible. However, note that staining the concrete slab might not result in a 100% colour match.

Consider It Decoration

One of the most challenging tasks is replicating an existing concrete look or application. You might not have the budget for a concrete overlay or for restaining the surface. In this case, you may choose to let the difference go and take it as a unique look to your concrete surface. The concrete contractor will repair any worn parts of the existing slab and match new concrete as closely as possible.

Conclusion

The colour of exposed concrete not matching the colour of an existing concrete slab should not be a major cause of concern. A concrete overlay can be the perfect solution. Alternatively, you can choose to restain the concrete slab or leave the colour variant as a part of the decorative aspect. At ReoCrete, we provide the best exposed concrete available in a wide range of colours. Contact us today for onsite delivery at the best prices.

How to Lay Concrete Slabs Correctly

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Concrete slabs are an important structural element of any building. Builders construct concrete slabs to createfunctional, flat surfaces. A concrete slab is usually several inches thick and can be supported by walls, columns, beams, or the ground. The primary function of the concrete slab is to transfer the load by bending in one or two directions. The slab must be laid correctly to avoid incidences like blisters, cracking, curling, and surface scaling. Below is a description of how you can lay a slab correctly for durable construction.

Site Preparation

Measure from the lot line to enhance accurate positioning of the concrete slab. Fix four stakes at the corners of the slab so that you can remember where the slab will be placed. Use a line level and string to see how much or little the ground slopes. This measurement will enable you to have a level base for laying the slabs.

An unlevel base can cause cracks or destroy the whole structure. To level the soil, you can move the soil to the lower end or dig out the higher side. It is also crucial that you know your soil. Sandy soil has no risk of cracking due to water content in the surrounding ground. Other soils, like clay and loam, needaround seven to eight inches of compacted gravel beneath the concrete.

Constructing Strong and Level Foundations to Install Concrete Slabs                                     

Choosing boards is the next step. The board size should match the size of the site.If they are not long enough, merging them is an option. Merging can be done using a cleat over the joint.Before applying the cleat, ensure that they are aligned. Also, use solid bracing so that the concrete does not push the boards out of place. Set the boards and ensure that they are straight. Drive the kickers into the ground at an angle and nail the top of kickers to the stakes. Next to the first one, place the third form board. Ensure the fill is hauled and tamped before placing the fourth side. To achieve a perfect levelling of the form boards, let one of them be higher when you hammer it to the stake.

Build and Pack the Base

The base should be able to drain to prevent cracking effectively. Measure the top of the forms to the ground using some string to know how much fill you will require. Do this more than once to be sure. After getting the estimate, place your fill and spread it, ensuring it does not exceed three inches.Tamp all layers well.

Slab Reinforcement with Steel Bars

Steel bars can be used to reinforce your slab for a solid and durable site. However, using still bars is a very labour-intensive task, which may require professionals. Hire experts will ensure your reinforcement is well done. You can also do it by yourself with steel bars, wires, and wire twisting tools.

Prepare for the Concrete Truck

Everything should be ready when the truck delivering your premixed concrete arrives. Concrete forms should be prepared and able to withstand the concrete. Call the contractor a day earlier to get helpful advice and ensure you have the right concrete estimates to avoid inconveniences.

Pouring Concrete and Applying a Smooth Finish

Place the concrete in its final spot. When the concrete has been entirely placed, smooth it and screed it. Use the bull float to completely smooth and remove any marks from the screed. Pass the bull float over until water is drawn to the surface. Allow it to harden, and then groove it depending on how big your slabs are. Use a floating iron to get rid of any imperfections. Allow the concrete to cure and keep it moist.

Conclusion

Laying a concrete slab is a critical stage of your construction. It is vitalthat you follow the best practices throughout the stages of concrete slab construction. Engage a qualified concrete supplier to ensure you are using top-quality premixed concrete and to help you with concrete estimations.

Dealing with Ambient Conditions When Placing Concrete Toppings

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Placing aconcretetopping is a part of many construction projects. If a concrete placement is done under extreme weather conditions, there is no guarantee that the surface will last. Additionally, under some ambient conditions, the workers on the ground may be at a higher risk of incurring injuries. Injuries are especially concerning where the slab is not strong enough to support the building’s weight. However, this does not mean that you should stop your project and wait for favourable weather conditions.  This article will look at how to deal with three main ambient conditions when placing concrete toppings.

1.    Hot Weather Condition

The ideal time to place concrete toppings is very early in the morning and late in the evening when temperatures are low. Working sites should also be under a roof to prevent direct heat from the sun. The engineer should order high thermal resistance steel bars andsteel reinforcingmesh from the steel suppliers to hold the concrete in such conditions. Besides mixing the concrete with cold water, using low heat cement can work better as well. After placement, cover the concrete with polythene to maintain moisture. Cover it prevents fast drying, which can cause cracks later.

2.    Cold Weather Conditions

If there is any ice or standing water on the areas where the concrete is to be placed, it should be wiped off completely. Heat generators should be placed at strategic positions at the construction site to increase temperatures when placing the concrete. The area should be surrounded by a temporary structure constructed with materials that are heat conductors. This structure helps in maintaining the generated heat. Reinforcing mesh, steel bars, and other construction materials should be warmed before contacting the poured concrete. Heat lights should stay on during and after concrete placement. Use the right amount of water when mixing because too much water can cause freezing. Consider using the cement best preferred in low temperatures conditions.

3.    Exposure to Rain During Placement

Rainwater should be drained away from the area where the concrete topping is being placed. This step maintains the strength of the slab. If the water is left before the drying period is over, it may wash away the cement on top. The water can also exceed the preferred mixing ratio. Excess water means weak concrete. Spreading a cloth sheet or polythene paper to avoid direct contact of raindrops with concrete also minimizes concrete damage on the placement day.

Conclusion

It is advisable to wait for favourable conditions to deal with concrete toppingsto be on the safe side and avoid stress. But some projects, like public roads, bridge construction, and essential services stations like hospitals, must continue. In these situations, best practices for placing concrete toppings under ambient conditions should be followed.