Research On Design And Performance Of Damping And High Strength Concrete

The damping capacity of concrete refers to the ability to convert the vibration energy into other forms and reduce the hazard of vibration, which could enhance the stability, security and durability of the structures, and is very significant to anti-vibration and disaster reduction. Concrete is the main civil engineering construction material. However, its damping capacity is low and mismatches its mechanics performance, which restricts the application of concrete in the structural engineering, especially under the frequent vibrating load for a long time. In view of this problem, the relations between the composition, structure and performance of concrete were studied systematically, the design method of damping and high strength concrete (DHSC) was proposed, the related rule between the composition, structure and performance was revealed and the key technologies of DHSC was grasped. The results provided the important basis and the theory for design, preparation and the application promotion of this kind of material.The original innovation of this thesis is summarized as following:In view of the trade-off problem between the damping capacity and mechanical performance of concrete, utilizing the structure vibration control principle, the damping function unit, concrete damper, was designed and prepared, which may obviously improve the damping capacity without undermining the mechanical performance of concrete. Based on this, the ideal structure model of DHSC which was spatial network distribution with the node of damper was proposed. The dampers distributed in this concrete homogeneously, and were connected by organic polymer material in the cement paste, forming a spatial network. Under the vibration load function, the energy was consumed by synergistic action of damper and organic polymer material and the damping capacity of concrete was improved, which could prevent the impairment of mechanical performance of concrete and avert the weathering erosion and durable problem because of organic polymer material incorporation into concrete. Results provided the theory for the preparation of damping and high strength concrete.According to the hypothesized model of damping and high strength concrete, the ideal structure, material design and preparation method of damper were invented. The damper was composed of two parts, which were the base material with high strength and the damping material. Study on the composition, structure and performance of base material, its ingredient and critical processing parameters were determined, and the base material with strength above 7.0MPa. Based on this, through the design and selection of damping materials, the match principle between base material and damping material and the damper preparation method was grasped, the mechanical performance of damper and the primary factor on its damping capacity were verified, the critical process parameters of damper were determined, and the damper structure, the performance and the damping capacity could be designed and controlled. These could provide the key material for the designing and control of damping performance of high strength g concrete.The influence of the composition on the damping capacity and mechanical performance was studied systematically. Results showed that mixing with proper dosage of damper could increase damping capacity of concrete without reducing its mechanical performance. The damping and high strength concrete could be prepared by controlling the water ratio and the volume fraction of sand reasonably, and mixing with proper dosage of assistance cementitious material, fiber and organic polymer material. Finally, the main technical parameter and mixt proportioning design method of damping and high strength concrete were proposed.The composition, structure and performance of DHSC were studied by the SEM, EDXA, mechanical performance and durability experiments. The excellent durability of DHSC resulted from the higher hydration degree and more dense structrue of paste stone and the lower content and orientation index of Ca(OH)₂ in the interface between cement and aggregate because of the inner humidity compensation of damper.The vibration fatigue performance of DHSC was studied on the basis of the Weibull distribution theory. Results showed that the fatigue life of concrete obviously reduced with the increase of vibration fatigue load, and obeyed two parameter Weibull distribution approximately. Compared with the same strength grade normal concrete, the fatigue life of DHSC was enhanced remarkably with the increase in its damping capacity; based on this, the vibration fatigue life forecast equations of DHSC were established under the different failure probability condition, which provided the essential reference for the production and application of DHSC.