Nowadays, reducing concrete deterioration and making a durability assessment of reinforced concrete structures are becoming challenging problems faced by both practical engineers and academic researchers. The primary objective of this study is to develop a new concrete durability enhancing admixture that utilizes natural polymer as a main admixture constituent, then to try to characterize the different durability aspects of concrete incorporating the new admixture, and lastly to give a synthetic durability evaluation of such a new generation of concrete by combining the principles of accelerated degradation testing and concepts of fuzzy logic....[ Read more ]
Nowadays, reducing concrete deterioration and making a durability assessment of reinforced concrete structures are becoming challenging problems faced by both practical engineers and academic researchers. The primary objective of this study is to develop a new concrete durability enhancing admixture that utilizes natural polymer as a main admixture constituent, then to try to characterize the different durability aspects of concrete incorporating the new admixture, and lastly to give a synthetic durability evaluation of such a new generation of concrete by combining the principles of accelerated degradation testing and concepts of fuzzy logic.
Firstly, an efficient test scheme for concrete water permeability is developed and implemented. To facilitate the permeability test, a specifically designed concrete permeability cell is developed. In addition, a new coating method for the concrete water permeability test is proposed, by applying a vacuum treatment during the coating to eliminate air bubble formations between specimen and coating materials. The experimental results show that the proposed concrete permeability test scheme can not only increase the efficiency, but also improves the consistency of the results of the water permeability test for concrete. Following that, an automatically controlled multipurpose accelerated concrete durability testing system is implemented. It is believed that the multipurpose control system has a promising future for the accelerated durability assessment of concrete.
Secondly, an innovative natural polymer based concrete durability enhancing admixture and concrete containing such an admixture have been studied systematically. By utilizing the newly developed water permeability test scheme and the automated multipurpose control system, a variety of concrete and mortar mixtures with a wide range of different quantities of the admixture has been investigated. Different durability aspects of the natural polymer modified concrete have been examined, including water permeability, depth of carbonation, frost resistance, and resistance to chemical attacks such as chloride acid and sulfate salt deterioration. It has been shown that the admixture can greatly improve the durability performance of concrete, especially its frost resistance. Furthermore, to characterize the durability enhancement of concrete incorporating the admixture, chemical water content measurement, mercury intrusion porosimetry, and a temperature depression test are employed. Due to its natural , renewability, low cost, and excellent durability improvement, the natural polymer based durability enhancing admixture provides a unique way of protecting concrete from deterioration.
Finally, a graphical interpretation and comparisons between the concepts of durability and service life is made. Based on the premise that the deterioration mechanisms and the surrounding aggressive environment of the concrete under consideration cannot be precisely described by classical logic, it is rational to accept that durability assessment of concrete is indeed a decision making process and belongs to the fuzzy logic problem domain. In this connection, a general framework of synthetic concrete durability evaluation is developed by combining the principles of accelerated durability testing and concepts of fuzzy logic.
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