The weight of concrete

Concrete is characterized above all by its high compressive strength and load capacity. Since the composite construction material also has a high density, the weight of concrete is not insignificant. However, not every concrete is equally heavy and there are differences in concrete weight.

Not every concrete is the same weight

Concrete consists of the three basic ingredients cement, aggregate (aggregate) and water. Already assuming the high weight, the concrete must have guess. Nevertheless, there are significant differences in the weight of concrete. For example, according to the ingredients, you can already differentiate between three types of concrete by weight:

  • Lightweight concrete: 1,000 to 2,000 kg / m³
  • Normal concrete: 2,000 to 2,600 kg / m³
  • Heavy concrete: from 2,600 kg / m³

The weight of concrete is based on dry bulk density

However, the data mentioned does not relate exclusively to the weight of concrete. These data also show the specific density of concrete. Indicated as dry bulk density, ie the density of dry hardened concrete, it gives information about the concrete composition of the concrete.

Theoretically, concrete can be produced from 300 kg / m³

Even though we started using lightweight concrete from 1,000 kg / m³, it is worth mentioning that lightweight concrete can theoretically be much lighter, at least from 300 kilograms per cubic meter. However, this concrete would be so unstable that there would be no or very limited use in the regular construction industry.

Impact of a concrete reinforcement

Now, however, other factors must be taken into account in concrete weight. So today concrete is mostly reinforced, so provided with iron or steel mats to increase the stability (flexibility and tensile strength). However, the reinforcement has a further increasing effect on the weight of concrete. For each cubic meter of reinforced concrete, another 100 kg of weight can be added to the dry bulk density.

Weight changes via the selection of the aggregate

The weight of concrete is thus determined by its density. Since the density of water and cement can not be changed, the weight difference and thus the different bulk density must be produced by the aggregate (obsolete aggregate). In fact, the raw density of lightweight concrete is so low because a porous aggregate is used here.

Special features of light and heavy concrete

In particular, in lightweight concrete but can also be distinguished, since supplement with closed structure (LBG) or Haufwerksporigem structure (LBH) is used. Incidentally, pore or gas concrete is not one of the lightweight concretes, as this building material is not concrete because, among other things, no cement is used. But even with heavy concrete, the final weight is determined by the density of the aggregate. For heavy clay blast furnace slag is often used, so for example lead or chrome slag.

Reduction of weight by means of packing

The density and thus the weight can also be influenced by other surcharges. Thus, plastic balls are used as so-called packing and mixed with the concrete. In particular, they should reduce the weight of concrete.

Until the 1990s, quenched and tempered concrete was used relatively frequently with such fillers. Meanwhile, however, it has been recognized that this concrete is more susceptible to external influences and thus tends to increased damage. With very high-quality concrete constructions one has therefore strayed from it.

The fact that the weight is also related to the density of concrete can be deduced from this, the lighter a concrete becomes, the more unstable it is. Lightweight concretes have so little load-bearing capacity that they are not suitable for structural components and walls. For this, lightweight concrete is characterized by other advantages such as a more favorable thermal conductivity. Due to the porosity, the lightweight concrete is significantly reduced compared to the thermal conductivity of conventional concrete.

Tips & Tricks

When calculating concrete, the bulk density of the aggregate is also of great importance. However, the calculation formulas are so complex that do-it-yourselfers usually mix concrete with simple rules of thumb.

Video Board: How to calculate concrete cube weight in KG by Learning Technology