Investigation of the effect of air-entraining admixture on the permeability and durability of concrete materials made of Portland cement type 1-525

In this research, the effect of the use of air-entraining admixture on the resistance and permeability of concrete materials made of Portland cement type 1-525 has been investigated. The effect of three different percentages of AEA was investigated on durability of concrete. The tests performed include the slump test, determination of volumetric mass of the fresh concrete, determining the temperature of fresh concrete, determination of the percentage of air content in concrete using the pressure method, the determination of compressive strength, the determination of volumetric electrical resistance, and determination of permeability coefficient. The results show that the amounts of used AEAs in concrete has a critical dosage (0.05% by weight of cement), so that the use of AEAs amounts less than this dosage has very little effect on creating enough air bubbles in the concrete. The use of a dosage of 0.1% AEA by weight of cement increased the workability of concrete about 26%. Moreover, the use of AEA has caused a significant increase in the workability of the fresh concrete without causing problems such as segregation and bleeding. In general, AEA led to a decrease in volumetric mass, compressive strength, electrical resistance and chloride ion diffusion coefficient of the concrete material. The results also show that the replacement of 1% of concrete's volume by the air bubbles decreases the compressive strength of concrete about 5%. The increase of the air content of concrete from 1.9% to 13.4% leads to a slight drop in the permeability coefficients of concrete.