Study On The Properties And Crack Resistance Microscopic Mechanism Of High Performance Concrete

Concrete is always used in the current engineering construction, and the quality or safety problems happen almost in every concrete project. The project construction experience shows that the performance of concrete always plays a decisive role in the engineering construction. As the main load-bearing system in all kinds of concrete structures, the concrete structures are required to be high quality on the temperature resistance, crack resistance and durability. In order to meet the normal working function in the various environment, the researches about the high performance concrete (HPC) have become one of the most difficult topics in the field of building materials. Under the supporting of the Ministry of Railways Project in China (No.:2010G007-K), the National Natural Science Fund Project (No.:51308477) and the Governor of Guizhou Province Outstanding Talents of Science and Technology Education Special Fund ([2012] 43), and also relying on Cheng-mian-le high-speed railway and Cheng-yu high-speed railway, this paper is trying to develop the high efficiency admixture of JX-HPC, JX-GBNHY, JX-CNH and alkali aggregate reaction inhibitors. They are all the efficient high performance on the microstructure of HPC. Some effectiveness have been discussed about the pore structure, thermal properties and volume stability of the developed product. Then the specimen ultrasound test and CT test have been taken to HPC samples; the conventional test and characteristic test have been done to reveal the developed products of HPC cracking macroscopic mechanism and the regularity of damage evolution and so on. Finally, taking a concrete arch dam built with anti-corrosion and crack resistance of HPC as the case, and its of three-dimensional fluid-structure finite element model has been analyzed to verify the test results. The main work and results are as follows:1) The characteristics and microstructure of HPC have been discussed; a HPC admixture has been developed according to the high efficiency water reducing agent and alkali aggregate reaction inhibitors;2) From the series of experiments, such as the fluidity of net cement slurry, mortar, cement water reducing rate adaptive, the allyl ether of polyethylene glycol and malefic anhydride were selected as the monomers, adding initiator and antimicrobial function of ally ether of polyethylene glycol (25 degree of polymerization) of polymerization of propylene glycol (5 degree of polymerization) for degree of polymerization monomer, with the reaction temperature of 90?, the poly carboxylic acid high performance water reducing agent was synthesized by the aqueous solution of one step synthesis process. At the same time, on the basis of the optimization of material ratio and polymerization process, a synthesized performance of comb type of graft copolymer super plasticizer was synthesized too. The effects of the copolymer with different dosage of net cement slurry and on the properties of slurry flow and keeping behaviors were tested, and the application of high strength concrete properties were discussed;3) Three grades of HPC (C40, C50 and C60) were developed, and the total gelled material, mineral admixtures, sand ratio, dosage of water use and dosage of admixture of concrete were given out; the manufacture high performance concrete thermal performance test analysis showed that cement early hydration heat release rate is reduced after adding mineral admixtures, and the heat release rate reached the highest rate of time back, but only single mineral ores, double mixing mineral powder and fly ash has effect to reduce early hydration temperature rise of concrete, while it has no obvious effect for later hydration temperature rise;4) Based on the sound detection platform with virtual instrument, the ultrasonic tests of the same kind concrete combining different admixtures, and the different kind concrete combining the same admixtures were carried out. The four different stages during concrete structure under load, the original fracture pressure, elastic deformation, plastic deformation and destruction, were verified. The pressure curves changed with time were contrasted and analyzed. Carboxylic acids and anti-crack materials can improve the C40 and C50 concrete performance, but the type of C40 concrete has better effect to improve performance;5) The CT test on high performance concrete was carried out; the CT images and CT number and CT number variance were analyzed, which reveals the concrete damage, the damage rate, body strain and CT number variations and the regularity of crack extension. Using the CT test results, the CT burst inside the concrete crack propagation model was built. The maximum design of stress value for no strain has been put forward in the concrete compression. If the concrete stress value was greater than the maximum design stress value, it could be damaged with cracks.6) Anti-corrosion and anti-crack of HPC is researched; the influences of early strength and volume stability for large volume HPC with admixture TK-GFZ2 were analyzed. Its application was achieved with an engineering example, and the three-dimensional fluid-structure coupling analysis was carried out. The effects of crack and corrosion resistance for the test developed HPC structure were checked.