What is the Workability of Concrete?
Workability of Concrete can be defined as a broad term for how new concrete can be mixed, consolidated, placed and finished without heavy loss of homogeneity.
Moreover, workability is a property which affects the strength, quality and cost of labor for finishing projects. However, one has to be more concerned with the quantitative features of this term to have a perfect grasp of this subject.
Types of Workability of Concrete
There are three major categories of workability of concrete, and they are:
● Unworkable concrete
Unworkable concrete is usually known as harsh concrete because of the coarse characteristics of the mixture. This type of concrete comes with huge segregation of aggregates and isn't appropriately lubricated.
The homogeneity of this type of workability of concrete is hard because it needs much strength for the mixture. The water-cement ratio of this type of workability of concrete is below 0.5.
● Medium Workable Concrete
This kind of workability of concrete is popular among many construction firms. It's simple to mix, place, and transport to all locations. You can also compact it without much segregation and homogeneity loss.
Moreover, this workable concrete is used for construction works that need light reinforcement to compact the concrete effectively. Usually, the water-cement ratio for this type is between 0.5-0.6.
● Highly workable concrete
Highly workable concrete is one of the most accessible types to move, transport and compact structures. This is used where there is no need to compact concrete massively.
This workable concrete flow effortlessly and cools down without any problems. However, it's likely to have much loss of homogeneity and segregation.
For this workable concrete, coarse segregation can be found at the bottom while the concrete stays up. It is commonly used for heavy reinforcements of structures where concrete vibration is impossible.
A typical example of the high workability of concrete is self-compacting concrete. The water-cement ratio is higher than 0.6.
Which Factors Affect the Workability of Concrete?
There are many factors which affect the overall quality of workable concrete; they include:
● Water content
Water content remains an essential factor when talking about the workability of concrete. The water content in the concrete mixture will have an impact on the compaction of the structure. The greater the water volume per cubic meter, the higher the concrete fluidity.
Moreover, to increase workability, there needs to be more water in the concrete. But, you should note that when the volume of water is increased, it affects the strength of the concrete. Also, when you add more water, expect to add cement for an ideal mixture.
● Mix proportions
Another important factor in the workability of concrete is how the aggregates - cement ratio is done. If it's higher than expected, lean concrete is developed, producing less quality concrete paste. With this inferior quality, lubrication is affected, and the overall workability is less.
However, if the aggregate cement ratio is less, a better mix is formed. This case ensures that more paste is available for lubrication processes.
● Aggregate sizes
That's why it's imperative to have less water for wetting the surface. When lubricating the surface, only a small paste is required to Minimize internal friction. Hence, reducing aggregates will result in less workability.
● Shape of aggregates
How aggregates are shaped influences how the workability of concrete works. Try to compare round or cubical-shaped aggregates to flaky aggregates; you will notice a difference in harshness. For milder concrete, round-shaped aggregates are better. This is because they have smaller surface areas and blinds than an angular aggregate.
Moreover, rounded aggregates have less frictional resistance, which is why aggregate offers better workability than concrete crushed sand.
● The surface texture of aggregates
Another factor that affects the workability of concrete is surface texture. When compared, the complete surface area of a coarse texture aggregate is better than that of a smoothly rounded surface.
This implies that rough textured aggregates have inferior workability, while glassy textured aggregates will show better workability than concrete. Also, the smooth aggregate provides better resistance capability due to a reduction of interparticle frictions.
● Grading of aggregate
This is a crucial factor that impacts the workability of concrete. A perfectly graded aggregate has little chance of voids due to the volume given. When the overall voids are minimal, extra paste is available for a better lubrication effect.
Moreover, this mixture becomes fatty and cohesive when more paste is available. This helps mitigate against the segregation of particles during the workability of concrete. When an aggregate is graded effectively, the less the void vintner and the better workability of concrete.
● Usage of admixtures
When you rightly use admixtures, it greatly impacts the workability of concrete. Plasticizers and superplasticizers help improve the quality of workable concrete. Using an air-entraining agent helps reduce internal friction because it's surface-active.
It helps act as some kind of ball bearing for particles and promotes easy mobility. Also, using glossy Pozzolanic materials helps increase surface area and provides an ideal lubrication effect for your work.
Tests for the Workability of Concrete
Several tests are carried out to determine how effective and performing a workable concrete is. Here are the types available:
● Slump Test
This workability of the concrete test is called a concrete slump test or slump cone test. It helps check the step-by-step inspection of the concrete lump. It determines how low the cost is and affects workable concrete.
● Compaction Factor test
This is the workability of the concrete factor test to determine the compaction degree achieved by work done. It is specially designed for lab use; however, sometimes, it can be useful in the field. This is a more precise test than the slump cone test and is better used for lower workable concrete.
● Flow test
This is the workability of the concrete test, which indicates the concrete quality by checking the cohesiveness and consistency required. This is fine by using standard concrete and subjecting it to jolting. It's recommended for the very high workability of concrete jobs.
On a final note;
Workability of Concrete is important when durability, strength and cheaper cost are what you desire in the work field. There are many types of workable concrete to use during a project, and there are many factors that influence how they work. To test how effective a workable concrete is, there are tests available that are reliable.
At USG ME, Wall Lining With Furring Channel/Stud on Block Or Concrete- is a good choice of workable concrete product.