Consistency of Concrete; How It's Measured, Why It's Important, and Relation to Workability

When it comes to construction projects, the consistency of concrete plays a crucial role in the overall success and durability of structures.

Long story short, the way you mix concrete has a significant effect on the concrete consistency, which can drastically affect the longevity of the whole building.

But let's take a step back.

What do we mean by consistency, and why is it so important? In this blog post, we'll dive into the world of concrete consistency, look at the importance of  mixing concrete thoroughly, and explore its relationship with workability.

We'll also discuss how you can measure the consistency of concrete accurately using Certified MTP's high-quality equipment. So, let's dive in.

The Importance of the Consistency of Concrete

In simple terms, concrete consistency refers to the degree of wetness or fluidity of freshly mixed concrete. This 'wetness' is a critical property that directly impacts the quality of the final product.

Here's why it matters:

• Consistency affects how well the concrete binds, influencing its overall strength, durability, and performance. Proper consistency helps ensure your freshly mixed concrete will lead to a structure that can withstand the test of time.
• The right consistency ensures you can easily manipulate the concrete, meaning you can easily place and compact it. Thoroughly mixed concrete in the right consistency results in a solid structure with minimal air voids and an aesthetically pleasing finish.

What Affects Concrete Consistency?

So, we know we need to the right level of consistency in our fresh concrete mixture, but how do we go about ensuring our concrete mix is up to scratch?

Several factors can impact the consistency of concrete:

Water-to-cement ratio

The ratio of water to cement in your concrete mix directly affects its consistency. Too much water can lead to segregation and decreased strength, while too little water can lead to low workability and difficulties in placement.

Coarse and fine aggregates

The size, shape, and gradation of aggregates influence the consistency of the concrete mix. The aggregates are the granular materials that make up the dry concrete mix, like sand, gravel, and crushed stone. These then get mixed with cement and water to form the final product.

Coarse aggregates are the larger particles, usually stone or gravel, that contribute to durability, whereas fine aggregates refer to the sand particles that fill in the voids to make the concrete workable.

These aggregates typically make up about 60-80% of the dry mix. When designing concrete mixtures, choosing the right combination of coarse and fine aggregates is crucial to create the right concrete consistency, and the same consistency consistently, for your purposes.

Admixtures and additives

You'll find that many dry concrete mixes contain other additives. These chemical and mineral admixtures can alter the consistency of concrete, either by increasing or decreasing its fluidity.

Temperature and weather conditions

Extreme temperatures and humidity levels can impact the consistency of concrete, causing it to set too quickly or slowly.

Workability: Understanding the Connection

Let's clarify the importance of concrete workability and its connection to consistency.

Workability is a measure of how easily you can mix, place, and compact concrete.

Obviously, it's imperative that those who work with concrete can use it for its intended purpose. Get consistency wrong, and you have an unworkable material, essentially useless for many construction purposes.

Consistency and workability are closely related; a concrete mix with the desired consistency will generally result in good workability.

How Can We Measure Workability and Consistency?

Since the consistency of your concrete is so important, you need accurate ways to measure it.

Let's run through some common tests:

Slump Test

A slump test is a simple way to measure the workability and consistency of fresh concrete. You fill a cone-shaped container, called a slump cone, with concrete in three layers, compacting each layer with a tamping rod.

Then, you level the top and remove the cone by lifting it straight up.

The concrete will "slump" or settle, and you measure the difference in height between the top of the cone and the highest point of the slumped concrete. This measurement, called the "slump value," helps you understand how easily the concrete can be placed and compacted.

A higher slump value means the mix is more fluid and workable, while a lower value indicates a stiffer mix.

This test is quick and easy and widely used across the industry.

Check out our various options for slump test equipment that can help you accurately measure concrete consistency.

Flow table tests

The flow table test is another method for measuring the workability and consistency of fresh concrete.

In this test, you place a specific amount of concrete on a flat, round table called a flow table. You then lift and drop the table several times, causing the concrete to spread out.

After completing the table drops, you measure the diameter of the spread concrete to assess the relative mobility. The greater the spread, the more fluid, and therefore workable, the concrete mix is. It isn't particularly workable if it only flows sluggishly and stays relatively central to the flow table.

The flow table test provides a visual representation to help you predict how the concrete will behave during placement, helping you determine if the mix is suitable for your project.

Take a look at the various flow table products available through Certified MTP.

Vebe test

Our third method is the vebe test, which works especially well for stiffer mixes.

In this test, you place a known volume of concrete in a cylindrical container and then cover it with a transparent, disc-shaped lid with a hole in the center. You then use a vibrating table to shake the container, allowing the concrete to spread and settle.

You're then measuring the time it takes for the concrete to resettle in its original volume under the vibration. This duration is known as the "Vebe time." A shorter Vebe time indicates a more workable and fluid mix, while a longer Vebe time suggests a stiffer mix with lower workability.

Certified MTP offers several different testing options that incorporate the vebe test principle, with products to suit a range of budgets.

Generally speaking, you'll need to consider the specific type of concrete mix you are working with, your expertise with concrete, and your budget to determine which testing method is the best choice for your needs.

Feel free to reach out and ask for advice from a member of our team for more information about the concrete testing equipment available.

Can I Improve the Consistency of Freshly Mixed Concrete?

Certified MTP offers a range of high-quality products that can help you improve the consistency of concrete and ensure you achieve the desired properties for your construction projects.

These products go beyond the step of accurately measuring the concrete consistency and cover a range ofconcrete testing steps:

• Mix Design - Certified MTP offers tools and supplies for concrete testing, such as sieves,air content meters, and specific gravity equipment. With these products, you can better and more accurately analyze the properties of your aggregates, cement, and other mix components.
• Quality control - Concrete test cylinders and molds help you effectively monitor and evaluate the strength and performance of your concrete mix. This helps you ensure that the mix maintains the desired consistency throughout the construction process.
• Expert advice - Certified MTP's experienced professionals can provide guidance on selecting the right equipment and supplies for your specific project needs.

Certified MTP's high-quality products and expert support can help you accurately measure and improve the consistency of your concrete mixes, ensuring that your project are smooth sailing and your structures are built to last.

Find the perfect tools for your concrete testing needs. Check out the full range of concrete testing products at Certified MTP or get in touch today.