Study On The Electrical Conductivity Of Concretes With Fly Ash

Concrete as the most widely and largely used building construction material has been paid much more attention to on its various properties for a long time. And a series of relative study and research had been carried out. However, there are few investigations on the concrete electrical conductivity. The existing research mainly focuses on the 2 fields: 1. produce the electrical conductive concrete by using conductive components; 2. test the concrete resistivity to indirectly reflect the changes of the other properties. The key of this study is that through the experiments the influences of several interior influence factors and exterior influence factors on the concrete inherent electrical conductivity have been investigated and analyzed in details.The mineral admixtures have be the indispensable component of modern concretes. Fly ash is the most widely and largely used one. And occasionally the content of iron oxide in the fly ash will be higher that is thought to be good to the electrical conductivity. Thus, the study on the effect of using fly ash, especially fly ash with high iron oxide content, on the concrete electrical conductivity is very useful.In this paper, through the parallel experiments on the normal concrete and the concrete with fly ash, the interior influence factors including the total binder dosage, the age, the fly ash dosage and the iron oxide content of the fly ash, and the exterior influence factors including water absorption and temperature have been analyzed comprehensively. Finally, the results revealed:1. No matter whether the fly ash is used, the concrete systematic resistivity both increases as the binder dosage increases.2. When the fly ash is used, in early period (before 7d), the concrete systematic resistivity slightly decreases as fly ash dosage increases. In later period (after 14d), it remarkably increases as fly ash dosage increases.3. No matter how much iron oxide the fly ash contains, the concrete systematic resistivity increases as fly ash increases. However, with the same binder dosage, the more iron oxide the fly ash contains, the lower the systematic resistivity is.4. The increase of water absorption will promote the concrete systematic electrical conductivity. And the more the fly ash is used, the less sensitively the concrete systematic resistivity reacts as the water absorption changes. In this condition, the iron oxide content of the fly ash has not obvious influence.