Concrete is a fundamental material in the construction industry, an excellent option for any type of building work. Fresh concrete, when setting and hardening, acquires a lot of resistance, thus providing durability and rigidity to structures.
It is also very versatile, because it adapts to the specifications of any building work.
However, in this article, we’re going to talk about fresh concrete, which we can say is the basis or origin of all the different types of concrete that exist.
Let’s begin!
What is fresh concrete?
Fresh concrete’s main characteristic is its plasticity allowing it to be molded, although this is not permanent factor.
It is considered to be fresh from the moment the concrete is created until the cement begins to set. In turn, this time frame is completely variable as it depends on the additives used, the temperature, the dosage of water, the kind of cement used and other factors.
Fresh concrete is a heterogeneous material, due to this, we can find it in up to 3 states of matter:
- Solid: When cement and aggregates are mixed (variable in nature and size).
- Liquid: Once water is added to the mixture.
- Gaseous: The air entrapped from mixing the mixture within the concrete mixer and the inclusion of additives.
Fresh concrete properties
Fresh concrete is the immediate result of mixing all its components. From the moment in which the mixture is produced, chemical reactions take place that give it its final characteristics, such as its outstanding hardness.
“These reactions can occur up to years after mixing.”
Here are fresh concrete’s main properties:
Consistency
Fresh concrete has the ability to deform. This property is measured by the descent in centimeters with an Abrams cone test.
Abrams Cone Test
Among all the tests that exist to measure the consistency of fresh concrete, the Abrams Cone is the most commonly used.
“It consists of filling a 30 cm high cone-shaped mold with fresh concrete.”
The reduction in height produced once the mixture is removed from the mold is the measure that defines its consistency.
Remember that some concretes are classified by their consistency, therefore, this test is very important.
Docility
Fresh concrete is very moldable, it allows to be moved from one place to another with whatever means we may have access to.
Homogeneity
All its components are distributed in similar proportions, obtaining a very homogeneous material.
Specific mass
It is the relationship between the fresh concrete’s mass and the volume it occupies. It can be measured with uncompacted or compacted concrete.
Handling time
Period of time between the mixing of the concrete and the beginning of the setting process. It determines the concrete’s handling capacity without reducing its characteristics.
Fresh concrete characteristics
These are fresh concrete’s main characteristics:
Easy to apply
After making the mixture, we just have to distribute it evenly and smoothen it out. Further into the article, we will see different ways to apply it.
Requires certain care
Although it’s easy to apply, it’s necessary to keep it in constant movement and wet in order for it not to dry out and become unusable.
Easy to move
It can be carried around with a wheelbarrow, bucket or concrete mixer.
It is economical
Fresh concrete is a very inexpensive material to obtain. It can be bought both privately in a workshop or by the cubic meter in a factory.
Fresh concrete composition
To create fresh concrete, we need 3 fundamental ingredients with which the mixture is made: water, sand or gravel and cement, all these ingredients adhere to each other, until forming a concrete mixture.
Cement
Generally made up of clay and limestones, which give the cement its binding effect. Cement, when in contact with water, hardens and, to keep concrete fresh, it must be continuously hydrated.
Water
Water activates the cement and makes it join to the other ingredients, in addition to allowing the calcification of the cement. If too much water is added to the concrete mixture, it decreases its strength and makes it difficult to handle.
Aggregates or gravel
Aggregates such as silica sand are responsible for providing durability and strength to the mixture, making them an essential component. However, we shouldn’t pour too much quantity. The correct amount enhances the properties and characteristics of the concrete, making it more durable and resistant.
Uses of fresh concrete
Once we have prepared the mixture, it can be used for many purposes. Here bellow we are going to explore some of them.
Housing construction
Fresh concrete can be used to bind bricks or partitions together, fill in walls, create building foundation or cover ceilings.
Producing building elements
This is one of the uses that requires the most amount of fresh concrete. Homogeneous partition walls are an example of building elements which are manufactured in mass which also improve production efficiency.
Elements such as columns, beams or footings are also manufactured.
Large structures
In the same way that we can obtain beams, columns or foundations, fresh concrete is also used to build bridges or viaducts.
Another of its uses is to obtain prestressed concrete. This technique makes building faster than any other conventional method.
It’s also used to create load-bearing walls or roof structures.
Roads and flooring
Within the types of fresh concrete, there is a specific one designed to build roads, pavements and highways, which is called hydraulic concrete. Its main characteristic is to resist traction forces and weight.
This hydraulic concrete is easy to handle and has a special mix.
How to pour or apply fresh concrete?
Fresh concrete can be applied in many ways. There are different techniques that are adjusted to the specific requirements of the work which is to be executed.
The one that we believe to be the most commonly used method is pouring it through a hose. By using this method, concrete is added directly into a “container”, which is known as formwork.
This technique is used more in buildings that don’t require large amounts of concrete.
Another way to apply it is by using a concrete mixer, in which the mixing and manufacturing process of the concrete takes place.
The concrete mixer has an arm that overturns the machine to apply the concrete easily and quickly.
In the event that the work that is to be carried out is very large, a concrete pump can be added to the concrete mixer, which facilitates its application and distribution.
Conclusions
There isn´t a more moldable, safe, durable, economical and versatile material currently on the market than fresh concrete.
Thanks to fresh concrete, many buildings and construction works have been executed with a total guarantee of safety, from decorative elements and housing, to larger works such as pipework, pavements, sidewalks, roads or bridges, as well as structural supports and beams.
You can make fresh concrete yourself at home, as it has the advantage that its ingredients are very easy to find and obtain.
References
These are some official documents and websites that we’ve used to compose this article.
- ocw.bib.upct.es
- construmatica.com
- juntadeandalucia.es
