A Study on the Properties of Concrete with Coated Granular Retarder and Healing Material

Abstract

Abstreat There are many study about concretes durability such as crack reduction, maintenance and repairing of concretes. Defect of concrete structure following built of massive and high-rise structure such as skyscraper, many kind of power plant and dam was occurred recently. From this reason, it is necessary to study about extension of mass concretes structures life. In case of mass concrete, when the concrete was placement, It has high temperature by hydration heat. The cracks due to the temperature difference generated by the hydration heat are likely to occur not only as micro cracks on the concrete surface, but also as cracks passing through the structure. This can have a great influence on the stability, usability and durability of the concrete structure. In this study, material which was fulfilled as retarder and self-healing was analyzed for extension of concretes structures life. For each formulation, 0.05%, 0.1%, 0.15%, and 0.2% of granular coated retarder were mixed with 5% of granular coated expansive agent simultaneously. The retarder reacted when high hydration heat occurred because of the paraffin coating. Setting time and Mock-up test showed the performance of the granular coated retarder. In addition, study on the crack closing after concrete placement by healing material which was coated by water-soluble film. Crack closing was confirmed by electron microscope and ultrasonic wave method. From this result, a developed materials was not effected on the concretes final properties and it can be one of the method to increase the structures life by controlling setting time and self-healing reaction.