风积沙与再生复合微粉对超高性能混凝土力学性能的影响

Effect of aeolian sand and recycled composite micro-powder on mechanical properties of ultra-high performance concrete

  • 摘要: 以废弃砖和混凝土制成再生复合微粉部分取代水泥作为辅助胶凝材料,以风积沙部分取代河砂协同制备超高性能混凝土(Ultra-high performance concrete,UHPC),采用修正的Andreasen-Andersen (MAA)颗粒堆积模型设计配合比。建立了考虑风积沙和再生复合微粉火山灰活性的抗压强度增长预测模型。研究了风积沙和复合微粉对UHPC力学性能的影响。结果表明:风积沙等质量取代河砂的取代率为30wt%、复合微粉等质量取代水泥的取代率为10wt%时,UHPC力学性能最优。颗粒材料的粒径分布最佳,形成了较高密实度的基体。同时,风积沙和复合微粉活性成分的水化贡献改善了UHPC的微观结构,进而提高其力学性能。

     

    Abstract: Ultra-high performance concrete (UHPC) was prepared by partially replacing cement with recycled composite micronized powder. The waste bricks and concrete were used as an auxiliary cementitious material. The river sand was partially replaced with anthracitic sand. The modified Andreasen-Andersen (MAA) particle accumulation model was used to design the proportions. A concrete strength growth prediction model considering the pozzolanic activity of aeolian sands and composite micro-powder was built. The effect mechanism of composite micro-powder and aeolian sand on the mechanical property of UHPC was studied. The results show that the mechanical properties of UHPC are optimal when the replacement rate of river sand by the equivalent mass of aeolian sand is 30wt% and the replacement rate of cement by the equivalent mass of composite micro-powder is 10wt%. The particle size distribution of granular materials is the best, forming a matrix with high compactness. At the same time, the hydration contribution of aeolian sand and composite micro-powder active components improves the microstructure and mechanical properties of UHPC.

     

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