Productivity Performance Estimation in Egyptian Construction Projects Based on Regression Analysis (Dept.C)

Abstract

Reinforcement corrosion is the main cause of damage and early failure of reinforced concrete structures. The protection system of embedded steel reinforcement from chloride induced corrosion involves several methods and techniques. One of these methods and techniques is using corrosion inhibitors admixtures (CIA) which added to concrete mix during mixing stage of concrete. These research aims to evaluate these admixtures (Sika Ferrogard®-901) in prevent corrosion of steel in concrete and their effect on concrete properties for fresh and hardened concrete. In this paper (CIA) used with different concrete contents and proportions. In this study, 150-mm concrete cubes specimens with high tensile steel bar grade (36/52) of 10 mm in diameter and 150 mm in length were embedded in each specimen during its casting such that 100 mm was fixed inside the concrete while the reminder 50 mm was kept outside. Three thicknesses of concrete cover were used; 25, 50 and 75 mm. After 28 days of water curing, specimens were transferred to dry for 24 hour, then the specimens were partially submerged in plastic tank filled with 6% NaCl solution Acceleration of corrosion rate test is achieved by continuous electrical current produced from power supply 30 volts for 240 hour, where volts difference was measured in volts between resistance 100 ohm and the reading was record every 12 hour. The corrosion current (Icon in Ampere) was calculated during the accelerated corrosion regime by using ohm's law by knowing measured volts difference and resistance. Faraday's law describes the relationship between section loss and corrosion current. Hence, calculate corrosion rate of steel reinforcement in concrete. The results show that for all mixes the increasing of concrete cover thickness reduces the corrosion rate of steel. Using 5% (CIA) by weight of cement where the optimum dosage of Corrosion inhibitors admixture from experimental tests is 5% by weight of cement reduce corrosion rate by 80 % with no side effect on concrete properties except bond strength decreased by 10%.(CIA) gave best results with concrete mixes which contains 15% silica fume and water to cement ratio 0.35 · (CIA) decreasing concrete cover required to prevent corrosion from 75 mm to 50 mm. (CIA) accelerate setting time of concrete, so it needs a retarded when used with concrete mixes.