Is Asphalt Insulator? 5 Facts You Should Know!

Asphalt is a black sticky, viscous liquid found in an amorphous phase. In this article, we shall discuss the electric and thermal conductivity of asphalt in detail.

Asphalt is an insulator but can be conductivity with the addition of impurities. It consists of compounds of hydrogen and carbon with a few portions of nitrogen, oxygen, and sulfur atoms. The bonds between hydrogen and oxygen are very strong, and no free electrons are present to conduct electricity.

Asphalt finds its uses in road construction, pathways, playgrounds, water retention from ponds, and soil retention. We shall further discuss the thermal and conductivity of asphalt in detail and clarify whether it is a good electric and thermal insulator. We shall also list some uses of asphalt as an insulator.

Is asphalt a good electric insulator?

A good electric insulator does not allow the electric flux to pass through the matter. Let us clarify whether asphalt is a good electric insulator.

Asphalt is a good insulator, as no electric current can pass through it. It has a cyclic structure with doubly bonded carbon and pi electrons that does not contribute to electricity generation. Also, free electrons are not available as all electrons are shared by the atoms to form covalent bonds.

Is asphalt a thermal insulator?

Thermal insulators do not allow heat to pass through and reflect the heat waves. Let us see whether asphalt is a thermal insulator or not.

Asphalt is not a thermal insulator as it can conduct heat energy. It can absorb heat energy when exposed to heat radiation and energy, thus increasing its internal temperature. At normal atmospheric pressure, the melting point of asphalt is 167 degrees Celcius. The thermal conductivity of asphalt is 0.75W/mK.

Uses of asphalt as an insulator

Asphalt is used for different purposes due to its insulation property and thermal conductivity. Let us list some of the uses of asphalt as an insulator.

  • Asphalt boards are used for the roofing along with the layers of fiberglass.
  • Asphalt is installed over the wooden matter for insulation.
  • Asphalt is used in railway tracks to prevent accidents caused by friction.
  • Asphalt is used in concretes, waterproofing, and for ceilings.
  • Asphalt is used to make lacquer that protects metals and wood.
Image Credit: Asphalt by Daniel Tzvi (CC-BY-SA 3.0)

Is cold mix asphalt an insulator?

Cold mix asphalt is a mixture of asphalt with aggregate. Let us discuss whether cold mix asphalt is an electric insulator like natural asphalt.

Cold mix asphalt is an electric insulator as the electricity does not pass through the cold mix and is a thermal conductor. Cold mix asphalt is asphalt mixed with aggregate during cold weather conditions. The strength of the cold mix asphalt is not as good as asphalt, and thus its thermal conductivity is more.

Is cutback asphalt an insulator?

Cutback asphalt is a liquid state of asphalt when mixed with petroleum. Let us discuss whether cutback asphalt is an electric insulator or not.

Cutback asphalt is a thermal conductor and electric insulator. It acquires heat energy and increases its internal temperature but does not transmit the electric flux. Cutback asphalt is a combination of petroleum solvent and asphalt cement. It reduces asphalt viscosity and increases its thermal conductivity.


We can conclude from this article that asphalt is a bad conductor of electricity and a good thermal conductor. The thermal conductivity of asphalt increases with the addition of impurities due to the availability of free electrons. It is used for various purposes, being an insulator and thermal conductor.

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