Types of concrete

trowel machine on finish concrete floor

This article explains what concrete is, details different existing types of concrete and lastly talks about polished concrete.

What is concrete?

Concrete is found in many of the constructions that surround us, it is used regularly in the construction industry for its strength and reliability, among other characteristics.

It is present in numerous constructions such as buildings, bridges, expressways, ports, levees, channels, tunnels, and more.

Types of concrete

So what is concrete? Well, it is the result of the mixture of various materials, such as water, cement, sand, gravel or crushed stone, which are called aggregates and some additives.

All materials together create a binding agent due to its great characteristic of keeping all particles together in a compact mass.

Concrete is mainly made up of cement and water, the rest is usually silica sand and additives. But it all depends on the type of concrete and its use.

Additives will help to change the color, delay or accelerate the curing time and provide impermeability to the material.

It is useful to say that not all concrete has cement as a binder, this will depend on the type of concrete to be used. For example, bitumen is used as a binder to build expressways, this mixture is very viscous, black and has a high-density.

Concrete is a very useful material, as it can molded easily and has high adhesion properties, in addition to being able to compact and harden in a few hours (with additives that accelerate the process), adopting a consistency similar to that of a stone.

It also offers a high resistance to very high intensity forces and compressive forces, but has a fault, it doesn’t behave well to flexion or traction, and it is for this reason why they usually have skeleton inside, this is what we know as reinforced concrete.

Concrete skeleton

Types of concrete

As we have already mentioned in this article, concrete varies according to its preparation. As a way to delve into this topic, below we will show the different and most common types of concrete.

Concrete type: Mass concrete

It’s the concrete that gets poured directly into ready-made moulds.

Mass concrete always refers to large volumes of concrete, and because of that large volume they may have cracking problems.

Commonly, mass concrete structures have dimensions larger than 3 meters, amongst them we can mention large foundation slabs and dams.

This large volume of concrete requires measures to minimize cracking, which is caused by thermal reaction within the internal part of the concrete, which can generate a lot of heat due to the hydration process of the cement, and the external part that may be cooling.

Influencing factors during this thermal variation are: the volume of the structure, the ambient temperature, the initial temperature of the concrete at the time of its pour. The type of cement, the content of the mixture and the curing program are also influential.

As a historical anecdote, engineers Ricardo Bellsolá and Bayo used hydraulic (mass) concrete in 1862 for the first time in Spain.

In the public works magazine of 1862, it is documented that this intervention with mass concrete took place in the construction of a bridge over the Tregua river, near the town of Villanueva de Cameros (La Rioja).This bridge had a span of 22 meters, but interest laid in an adjacent work of 3 meter-span and 4.5 meters high that was executed in a monolithic way, that is, made all in one piece by using  hydraulic mass concrete.

Types of concrete: Cyclopean concrete

This type of concrete is a mixture of simple concrete and large size stones.

The most correct elaboration of cyclopean concrete would be made up of 60% simple concrete and 40% of stones.

Cyclopean concrete

These stones must be washed before being placed into the mixture, and each one of them must be surrounded by cement.

This indicates that in this type of concrete there must be a certain distance between the stones and that this distance must be filled with concrete.

Although it’s a structural element that resists compression forces due to the weight of the structure itself, this is a type of concrete that is currently unused. In the past, it was widely used for constructions with minor loads or for fences.

Types of concrete: Lightweight concrete

This type of concrete has a low density and high thermal insulation.

It’s recommended for constructions that require the least amount of weight possible as long as its mechanical performance is maintained.

Lightweight concrete block

Lightweight concrete consists of water, cement, polystyrene particles, and additives. This lightweight concrete is similar to cellular concrete as they both are low-density concretes.

Some of the main uses for lightweight concrete:

  • Sandwich panel roofs.
  • Repairs and restorations with screeds, vault fillings, leveling for wooden floors, etc…
  • Leveling concrete between floors.
  • Insulating cladding by using formwork on vertical surfaces in prefabricated houses.
  • As thermal insulation and anti-humidity screeds to go over the ground.
  • Thermo-acoustic insulation and slope formation on flat roofs.
  • Repairs and restorations with screeds, vault fillings, leveling for wooden floors, etc…
  • Repair and restoration of roofs and terraces in poor condition.

The following is a summary of the materials used to make lightweight concrete.

Unprocessed natural light aggregates:

  • Pozzolan
  • Travertines
  • Lapilli
  • Volcanic tuffs

Processed natural light aggregates:

  • Expanded clay
  • Expanded glass
  • Vermiculite
  • Expanded perlite
  • Synthetic shale
  • Expanded shale

Unprocessed light industrial aggregates:

  • Blast furnace slag
  • Pulverised fuel ash

Processed light industrial aggregates:

  • Expanded slag
  • Slag foam
  • Expanded ashes
  • Synthetic ashes

Processed light industrial aggregates:

  • Plastic particles
  • Cereal husk
  • Cellulosic shavings
  • Porexpa

There are recommendations regarding the use of this concrete, such as pre-moistening the support’s surface, so it doesn’t take the moisture from the mixture.

Another recommendation would be to place rocks manually and carefully to avoid misplacing them and not damaging the adjacent structures.

Evenly spreading the mixture and avoiding premature drying is vital to ensure a good curing of the concrete.

This type of lightweight concrete can be nailed or sawn thanks to its low density. You can also create large pieces with it and lighten structures.

Elements that don’t require great strength can be built with a lightweight concrete, such as partitions, floor slabs and fasade cladding.

Types of concrete: Structural concrete

This type of concrete, structural concrete, is the type normally used for any type of structure, it can be either civil construction or buildings.

The main characteristic of structural concrete is to improve structure durability.

Types of concrete: reinforced concrete

Reinforced concrete is the union of concrete with a round iron metal skeleton.

It provides higher resistance to compressive, tensile and torsional stresses than if it were applied without the metal skeleton.

It provides higher resistance to compressive, tensile and torsional stresses than if it were applied without the metal skeleton.

Reinforced concrete or reinforced concrete

This type of concrete is the most used to build bridges, all kinds of buildings, dams, tunnels, culverts, roads, liquid conduits, tanks, retaining walls, footings for walls, columns, and others.

Despite being so useful and offering so many benefits when building structures with a better stability, it also has a negative aspect, future modifications are very difficult to achieve, due to the existing metal skeleton.

Reinforced concrete characteristics

Some of its main characteristics are:

  • Anti-seismic structures are made with reinforced concrete, due to their great weight and volume.
  • It has a very high strength-durability ratio.
  • High traction tolerance.
  • Construction styles with reinforced concrete: skyscrapers, the great Art Deco buildings of New York were achieved thanks to the use of this material.
  • It does not need a lot of maintenance and it is also very durable.
  • Because they have almost the same expansion coefficient, concrete and steel bond strongly.

Interesting definitions regarding reinforced concrete

Within the field of reinforced concrete construction, there are some definitions that would be good to know, among which we have:

  • Main or longitudinal reinforcement: this is the one used to absorb the tensile stresses caused on thelower part in beams with combined bending.
  • Secondary or transverse reinforcement: it maintains the position of the longitudinal reinforcement when the concrete is still in a fresh state and reduces the length of their curvature.
  • Tying rebar: small bar or wire that is responsible for holding toguether  and confining the steel bars such as stirrups and ties.
  • Distribution bars: they are responsible for maintaining the distance and the correct function of the main bars in concrete slabs.
  • Retraction bars: they are those that are installed in the slabs where the flexural reinforcement has only one direction.
  • Anchor bars: its a bar with a seismic hook on one end, and another one no less than 90º, these must link peripheral longitudinal bars.
  • Seismic hook: it’s a stirrup or tie hook with a 135º bend, which joins the longitudinal skeleton and is projected inwards.

Brief introduction to reinforced concrete historical dates

In 1854, Lambot discovered that by joining concrete with an iron reinforcement, it increased considerably and is how he built the first boat made with these materials.

In 1861 a patent was obtained for the execution of certain construction works with reinforced concrete.

In 1867 a patent was also obtained to build cubes and pipes, reducing the thickness of the structures.

Then in 1875, works of greater importance and magnitude were achieved.

In 1884, the German industry obtained the rights to Monier’s perfected patent to use in their country.

From 1890 onwards, this method of construction became generalised in most construction works.

Types of concrete: Prestressed concrete

Patented by Eugène Freyssinet, this type of concrete tries to overcome the natural weakness of concrete when in tension.

It’s a type of industrially built concrete, consisting of concrete and steel, which has been subjected to compression stresses during production.

Pre-stressed concrete

The main goal of this prestressed concrete is to increase its tensile strength, by introducing artificial compression stresses before external loads are applied.

Thanks to this technique, we can achieve a higher structural load capacity, eliminating cracks during all stages. This also ensures an increased durability of the construction.

It also provides faster construction.

Now what is polished concrete?

Polished concrete is a finish for concrete flooring. We could say that it’s a finish which largely improves concrete floors.

Polished concrete polishes and smooths the surface and helps prevent cracking , moisture problems, and offers a much harder and more resistant floor that allows the circulation of heavy machinery, spillage of liquids, and promises easy and economic maintenance whilst forgetting about dust problems that are no longer generated with such a finish.

The good thing about polished concrete is that it’s a valid treatment for both new and worn industrial floors.

Floors on wich the polished concrete treatment is carried out on, achieve a new appearance, in addition to the benefits in strength and durability.

In terms of aesthetics, it’s an elegant and shiny finish. It reflects light and homogenizes the entire flooring.

The BECOSAN® treatment is carried out in all kinds of industries throughout the 5 continents. Information about treatment is given here.

Below is an explanatory video to find out what offers and advantages a polished concrete floor has with this treatment.

BECOSAN

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