INHIBITION OF CONCRETE COMPOSITE CORROSION BY COMBINED ADDITION OF SODIUM NITRITE AND SODIUM SILICATE

Studies of the inhibitory properties of sodium nitrite in a combined additive with sodium silicate for corrosion of reinforced concrete were carried out. It was found that an increase in the concentration of sodium nitrite in the combined additive with sodium silicate leads to a decrease in the strength of concrete after curing in air for 28 days. However, when concrete containing more sodium nitrite as an inhibitor is corroded in a mixture of 1% hydrofluoric acid (HF) and carbonic acid (H2CO3), its compressive strength decreases less. This is confirmed by cases of frequent splits of samples during shock-pulse testing. The lowest number of splits was observed in samples containing 3.2% sodium nitrite and 0.8% sodium silicate, and the highest number was observed in samples containing 0.8% sodium nitrite and 3.2% sodium silicate. Using the contact corrosion method, corrosion diagrams of reinforcement made of St3 steel in concrete without additives and with combined inhibitory additives of sodium nitrate and silicate are constructed. Corrosion diagrams allowed to determine the rate of corrosion of steel reinforcement in concrete with inhibitory additives of various compositions. Additives contribute to a rapid decrease in the value of the corrosion current density. Increasing the concentration of sodium nitrite in the inhibitory additive leads to a decrease in the rate of anodic dissolution of reinforcing steel. The introduction of 3.2% sodium nitrite and 0.8% sodium silicate into concrete slows down the anodic dissolution of reinforcing steel by almost 2 times.