Document Type : Original Article
Mustansiriyah University/ College of Engineering/ Materials Engineering Department Baghdad-Iraq
This study aims to see how employing lime peel powder could reduce corrosion and increase compressive strength in carbon steel mortar. Mortar samples were prepared with the addition of the different weights of carbon steel fillings and 10, 20, and 30 gm lime peel powder as a sand substituent. The samples were conducted to compressive strength test and corrosion rate by weight loss method. pH and salt concentrations were also studied as varying factors. The first group mortar samples were immersed in water for 7, 14, and 28 days, while the second group were immersed for 90, 150, and 210 days. Furthermore, the samples were immersed in different pH solutions of 3, 5, 7, 9, and 11 and different salt concentrations of 5% and 10% calcium carbonate for the same periods. The first group were dried and conducted to the compressive strength test, and the second group were conducted to corrosion rate test. The results showed that the best weights used to eliminate corrosion rate and improve the compressive strength of mortar samples were 5 g carbon steel filings and 20 g lime peels powder addition. The findings show that the corrosion rate and compressive strength of mortar samples increase as they spend more time in the water. The corrosion rate was increased in acidic and alkaline solutions, but its value was higher in acidic than in alkaline solutions. The less corrosion rate for all mortar samples immersed in different pH solutions was at pH 7. In addition, the mortar samples corrosion rate increased with increasing the salt concentration. The best compressive strength and corrosion rate values of carbon steel filings mortar samples were at pH 7and 5% salt concentrations at 28 and 90 days, respectively. The reasons of using lime peels powder are: 1) it is used as recycled waste material, 2) the adsorption of lime peel powder extract on the surface of the steel filling leads to the formation of a protective layer that inhibits the action of the corrosive solutions and this layer develops in thickness and effectiveness with time. In conclusion, the inhibiting efficiency of lime peels powder is not due to the antioxidant activity of its compounds but also to the precipitation of a surface film, which prevents or eliminates corrosion rate and improves compressive strength.