混杂纤维增韧高强机敏混凝土的研究

The main contents in this project include: study of the complex mechanism and smart characteristics of high strength and smart concrete with hybrid fibers; seting up a mechanical model for the new type of reinforced composite; exploring the influence of fiber parameters, materials components and microstructures on the electrical conductivity and Seebeck effect of the composite; discussing and analyzing the relationship between electrical conductivity and the inner parameters of composite such as strain, temperature and damage under loading process. Test and research results indicate that by using hybrid fibers based upon different geometric shapes and elastic modulus, in a relatively smaller volume fraction (less than 0.5%), the compressive and tensile strengths of concrete are improved obviously. Moreover, some toughness index and fracture energy for the hybrid fibers reinforced concrete are increased more than 200% and 21 times, respectively when compared with control concrete. Percolation theory is suitable and applicable for the research of electric properties of smart concrete, and it is found that the percolation threshold is the key to produce the stable electric concrete. The quantitative relationships between electrical conductivity and the inner strain, temperature and damage of smart concrete under tensive, compressive, flexural and fatigue loading process are setup. Negative temperature coefficient (NTC) and Positive temperature coefficient (PTC) effects were found in the carbon fiber concrete, and the NTC to PTC transition process could be quantitative described by a phenomenological model. Moreover, it is found that there exist outstanding Kaiser memory effect during the loading period of the carbon fiber concrete, which make it possible to trace to the loading history of materials. The above research work could offer very important theoretical base and technical avenue for the self-diagnosing of concrete, design of intelligent concrete structure, health monitoring and life evaluation.

通过计算机模拟和材料试验相结合，研究碳----玻璃混杂纤维增韧高强混凝土的复合机理和机敏特性，建立该新型复合材料增韧的力学模型，探讨纤维参数、材料组份和显微结构对电导性能和热电效应的影响以及构件承载过程中电导率与材料内部应变、温度、损伤等变量的关系，为混凝土智能结构的设计、健康监测和寿命评估提供理论依据和技术手段。