关键词: 超高性能混凝土; 配合比优化设计; 最紧密堆积理论; 最大固相含量法; 水化程度; 微观形貌;

Abstract: In the actual production process, the preparation and performance of ultra-high performance concrete(UHPC) are often restricted by the raw material quality.Therefore, based on the closest packing theory, the improved Andreasen model and the least square fitting algorithm were used to calculate the closest packing ratio of powder in the existing UHPC matrix.Then different UHPC mix proportions were designed according to the calculation results.The bulk density of UHPC matrix with different mix proportions was tested by maximum solid loading method.The mechanical properties and shrinkage properties of UHPC with different mix proportions were tested according to relevant standards.The hydration degree of cementing materials was tested by chemical combined water method, and the micro-morphology of the matrix at 3 d and 28 d was analyzed by scanning electron microscope.The results showed that the cement content in UHPC decreased significantly according to the proportion design based on the closest packing theory.The mechanical properties of UHPC and its matrix with different proportions after optimization were consistent with the test results of maximum solid loading method, and the maximum compressive strength of UHPC matrix was 136.1 MPa.In summary, UHPC proportion design based on the closest packing theory and the maximum solid loading method can overcome the limitations of materials and obtain UHPC proportion with less cement content and better performance.

Key words: ultra-high performance concrete; optimization design of mix proportion; closest packing theory; maximum solid loading method; hydration degree; micro-morphology;