Investigation of the Causes of Petrochemical Concrete Structures Destruction In Mahshahr and Proposed Solutions
Today, most civil structures are built of concrete, which’s use is increasing daily. Due to ignoring the principles of constructuion (for the durability of the concrete), corrosion causes substantial costs to the structures after a small period of operation that in some cases rebuilding the structure is even more difficient rather than renovating it. This issue is even more critical about the structure exposed to sea water and the low service life in the southern coastal structures has confirmed so. Also, with huge resources of gas and oil being discovered as well as the construction of large petrochemical plants in the Persian Gulf have led to the need for major construction and development projects in the area. Hot and humid climate and minerals in the region are showing signs of deterioration, including numerous cracks, corrosion, efflorescence and welting the concrete. Reinforced concrete structures in the south of the country are exposed to chemical or electrochemical damage. The most important corrosion factor is due to air carbonation phenomenon (occurs as a result of carbon dioxide in the air) and chloride penetration (which passes through the concrete and reaches the reinforcement). The effects of corrosion and cracking and collapse of concrete and concrete sulfate decrease the beneficial life of the structure significantly. This type of damage is greater in the tide region because due to wetting and drying, chloride penetration influx into concrete is intensified and as a result the corrosion rate increases. In order to reduce the damage of reinforced concrete structures different methods are used and most important is improving the quality of concrete. In this study the prevention cases of reinforcement corrosion have been investigated and the type of cement and its additives such as silica and penitron were oxamined. The results indicate that the coating material consisting of penitron penitron increases cylinder compressive strength. But the main benefit of penitron is preventing the concrete’s penetration. The best materials were selected by performing experiments and accordingly to the weather of Mahshahr, Samples of reinforced concrete structures with water-cement ratio of (w / c= 4% , w / c = 34%) and the lubricant of 6%- 2% range were built with a fixed slump, and taken under pressure tests. The results of the corrosion tests showed that he use of cement containing 10% silica with 34% water- cement ratio, armature FRP and penitron materials are the best technical and economic proposal in order to reduce corrosion in Mahshahr.
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