Research Of Characteristics Of Interfacial Zone And The Durability Of The High Performance Concrete Made-up With Mixed Sand

Combining the current situation of superfine sand yield rich and natural sand in shortage in Chongqing area, the general trend indicates that high performance concrete is made from fine aggregate which consists of mixed sand instead of natural sand. The dense positive fill mix proportion design carried out on the basis of positive fill density test, the research on the interfacial characteristics and durability of mixed sand high performance concrete was gradually expanded from macro to micro relying on mix design results, and the sand mixed high performance concrete was used in highway engineering Yongchuan Yangtze River Bridge. By testing and analysis, theâ‘ Through the dense positive fill experiments, the best filling sand mixture ratio of middle sand filling gravel and mineral superfine sand doped filling gravel were42%and8%,the maximum mixing unit weight of solid granular material can reach2196kg/m3, thereinto, the test mixed sand was prepared by the mechanism sand and fine sand quality mixed by ratio of7:3.â‘¡Using the dense positive fill mix proportion design method, the concrete was expanded with same water-binder ratio and same water reducing agent ratio.According to the performance test results, the adequate grout surplus coefficient n was selected at1.25.The amount of each raw material was determined on this basis, achieved the goal of increasing the degree of compaction of the concrete mixture.â‘¢Contrast test of four different gravel materials with same ratio were performed, comparing the performance of concrete prepared under different kinds of coarse and fine aggregate with the same ratio. Cube compressive strength, static elastic modulus, anti-carbonation and volume stability of concrete mixed sand are better than natural sand concrete, but the work performance, resistance to water and chloride ion penetration of natural sand concrete are better. Limestone gravel concrete performs better mechanical properties. Granite broken pebble concrete overall impermeability is superior concrete rubble, but the former carbonation resistance is less than the latter.Overall, the changes of rock lithology showed no significant influence on concrete in long-term development. Limestone gravel and natural sand were differentiate prepared as coarse and fine aggregate concrete performs the highest post growth rate of shrinkage. Crushed granite gravel and mixed sand were prepared as coarse and fine aggregate concrete showed a better overall performance.â‘£By scanning electron microscopy image analysis, high performance concrete interface macro and micro characteristics showed good consistency.Summed that the development law of morphology of transition zone which was in interface between the different aggregate and slurry. The macroscopic behavior was better explained from the micro level, especially for the formation mechanism for high-performance concrete durability.