When constructing a house, one of the most important factors that a homeowner considers is the energy consumption of the building. The same goes for builders and developers. The use of concrete and the value of its thermal conductivity plays a vital role in this regard. Heat transfer and dissipation through concrete walls or roofs directly impact the overall energy use and consumption.
This led us to an important question; does concrete have high thermal conductivity, or it has a low thermal conductivity? Only after getting an answer to this question will we be able to use the concrete in the best possible manner as far as energy consumption and heat dissipation are concerned.
With the growing population and considering the effects of climate change, energy conservation has become a need of the hour. Given the fact that most people spend their maximum time living indoors, the heating and cooling elements of the building directly related to the comfort and thermal conductivity of concrete can help significantly on this matter.
The facility to transfer heat is subject to thermal conductivity. In simpler words, you can say that it is the heat conduction capability that is represented by the thermal conductivity, which is also denoted as k-value.
Concrete and thermal conductivity
Concrete is one of the elements that is common all over the world and is used in the construction of buildings, pavements, motorways, roads and bridges, architectural structures, walls, and so many other countless applications.
The wide array of applications is made possible because of the advantages concrete offers over other materials. Widely available around the globe, concrete is readily available and is inexpensive. Moreover, it can be forged into different shapes and offers excellent water resistance. Above all of that, it requires zero maintenance.
Nevertheless, when it comes to thermal conductivity, concrete is a poor conductor of heat. Having said that, concrete can be used regardless of the surrounding temperature. Instead, the concrete gains strength and hardens when it sets.
Being a poor conductor of heat, concrete offers high-temperature resistance, which makes it suitable for a number of applications such as fireproofing steel material.
The low thermal conductivity means less heat transfer and, as an outcome, lower energy consumption.
Measurement of concrete thermal conductivity
There are different methods being used for this purpose, but there is not enough data on which method is the most suitable. Different methods may provide you with unlike results. No matter if you are calculating the building energy consumption or thermal conductivity of a material, accurate results are important to achieve, or else, there is no use of measurement.
Typically, steady-state, and transient methods are used for the calculation of concrete thermal energy.
The transient method is based on the change in temperature and time over a certain period. Whereas the steady-state method does not depend on time, and it is a constant heat transfer.
Regardless of the method you choose, there will always be some factors affecting the results and the choice of the method you make. A few important factors are discussed below.
Factors affecting the concrete thermal conductivity
Concrete is a form of porous material, and for that reason, it has a thermal conductivity that can be low or high. The property of thermal conduction is affected by several factors such as concrete density, type of aggregate, moisture, and the outside temperature. Deviations in any of these factors will affect the overall results.
Most importantly, the type of concrete has a major role in depicting thermal conductivity. There are several types of concrete that are classified on the factors of making material, density, and stress condition.
The plain concrete that is commonly used consists of cement, sand and construction aggregates are used in structures where high tensile strength is not required. While lightweight concrete is the form that has a density of less than 1920 Kg/m3.
The only thing that differentiates between the two when it comes to thermal conduction is their k-value. The plain concrete can have a k-value as high as 12, and on the other hand, the lightweight concrete has a k-value of 0.3 at most.
This shows that concrete can have high thermal conductivity and as well as low thermal conductivity when compared with each type. It is on the application and the requirements that define which concrete type to use. There are other types of concrete as well having different thermal conductivity values.
It is not only a matter of energy efficiency and conversion; knowing the thermal conductivity of concrete is important in all kinds of applications where it is used. For example, the construction of bridges will require a different amount of conductivity as compared to the construction of a house. Each type of concrete has its own application considering in mind its thermal conductivity.