Lightweight clay bricks have low thermal conductivity and small pores, so they can play a role in thermal insulation.
In the process of thermal insulation, the pores of light bricks are very small, the gas flow rate in the pores is very small, the convective heat exchange of gas in the pores is small, the smaller the pore size of the pore, the worse the fluidity of the gas in the pores, the smaller the convective heat exchange. Radiative heat transfer occurs mainly through stomata, but radiative heat transfer through stomata is small.
Actually, most of the heat is transferred through the solid phase, and the light clay brick has a good thermal insulation effect in the gas phase. The smaller the area ratio, the lower the heat transfer through the solid phase. The influence of solid-phase heat transfer on light clay bricks is negligible.
The thermal conductivity in the process of thermal insulation is mainly air, and the thermal conductivity of air is much less than the thermal conductivity of the solid phase, so the thermal conductivity of air to the pores is also very small.
As a rule, the more complex the crystal structure, the lower the thermal conductivity. The atoms and ions of clay light bricks are arranged randomly, so the pores are low. During use, the possibility of gas, heat and solids passing through the pores is not very high. Therefore, light clay bricks play the role of thermal insulation.
Of course, the lower the bulk density of light clay brick, the better the thermal insulation effect, but the strength of light clay brick with low bulk density decreases with decreasing volume. If light bricks are used as the thermal insulation layer, refractory concretes are poured in the working layer, or heavy bricks are erected, the thermal insulation effect is good.
If refractory concrete is used for the working layer, the thermal insulation effect of light clay bricks is better than that of fiber wool and fiber boards, because the release of water when the concrete drains will cause the fiber cotton to be lost. its thermal insulation effect after absorbing water. Light clay bricks will not be affected by water discharge.