Influence of cold joints on the corrosion of steel in concrete mixed with seawater under varying fly ash ratios

• Main Authors: Dalangin, Christian Huy S., Gonzales, Jayson Marco E., Ilagan, John Christopher G., Yu, John Christopher S.
• Format: text
• Language: English
• Published: Animo Repository 2016
• Subjects: Steel > Corrosion > Testing; Joints (Engineering); Fly ash > Testing; Civil Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/8973
• Institution: De La Salle University

This study presents an experimental study on concrete mixed with seawater under varying fly ash ratios in which the compressive strength and macro-cell corrosion were analyzed. The study involves the investigation of corrosion rates of steel reinforcements in concrete with cold joints in order to analyze the plane of weakness it creates on structures which turn has an effect on corrosion. This is in line with the simulation of structures near large bodies of water that are mostly exposed to corrosive elements. The study involves eight types of mixes consisting of 0%, 20%, 30% and 50% fly ash replacement ratios and seawater content. Cylindrical concrete specimens were cast and cured for compressive strength testing. With the evaluation of macro-cell corrosion, rectangular prism concrete specimens with segmented steel were cast. The rectangular specimens were cured and tested weekly for electric current results which later on would quantify corrosion. The corrosion in the steel bar was evaluated by macro-cell current density testing which utilizes a zero resistant ammeter as a potentio stat. The corrosion rate was determined through the current from the voltage drop which will be divided by the cross sectional area of the reinforcing steel bar. Results have shown that freshwater mixed concrete containing 30% fly ash to be the optimum mix considering compressive strength and corrosion resistance. The compressive strength and corrosion rate also decreases as fly ash content increases. The curing method and presence of cold-joints also significantly affect the corrosion rate of the specimens.