【作者】 蔡基伟；

【导师】 周明凯；

【作者基本信息】 武汉理工大学 ， 材料学， 2006， 博士

【摘要】 现行标准对机制砂石粉含量的限值存在争议，同时也制约了机制砂的应用和石粉的合理利用。本文在分析测试机制砂与石粉特性的基础上研究了石粉对水泥性能和混凝土性能的影响规律，探讨了混凝土用机制砂石粉含量的限值，提出了含石粉机制砂混凝土配制特点与配合比设计原理，分析了石粉在机制砂混凝土中的作用机理。 研究了57个机制砂试样主要特性指标的统计分布规律和指标间的回归关系，提出了生产机制砂的细度模数与2.36mm粒级分计筛余的关系。应用数字图形处理（DIP）技术研究了试验机制砂的颗粒形貌特征及与粗糙度测试值的关系。研究了机制砂堆积密度和石粉含量的关系，以及MB值与含泥量和土质的关系。采用激光粒度分析仪测试了石粉颗粒分布特性。 研究了石粉对不同品种水泥、不同石粉对水泥、石粉对掺不同混合材料水泥的标准稠度用水量、凝结时间和强度的影响，以及石粉代砂对水泥砂浆稠度、强度、收缩与抗裂性能的影响。 研究了石粉含量对机制砂混凝土性能的影响。讨论了最佳工作性与水粉比的关系，提出了泌水潜伏时间的概念及与泌水率的关系。对于级配不良的机制砂，石粉可以改善机制砂混凝土的工作性。随着机制砂石粉含量的增加，混凝土的抗压强度、抗折强度和干缩率逐渐增加，达到峰值后减小。机制砂混凝土轴心抗压强度和劈裂抗拉强度均高于天然砂混凝土，且提高幅度随石粉含量增加而增大。机制砂混凝土的弹性模量取决于石粉对强度和浆体数量两方面的影响。机制砂混凝土的干缩和徐变均小于天然砂混凝土。石粉能够增强混凝土的抗渗性能。高强度机制砂混凝土具有很高的抗冻性，石粉含量对其影响不明显；中低强度机制砂混凝土的抗冻性能低于天然砂混凝土，石粉可使抗冻性能略微改善。据此提出了中低强和高强混凝土用机制砂中石粉的适宜含量指标分别为10～15％和7～10％。 研究了石粉在混凝土中的作用机理，石粉作为晶核对水泥水化起到促进作用和匀化作用，石粉中的CaCO₃参与C₃A的水化反应生成水化碳铝酸钙，对水泥水化有增强作用。石粉具有使混凝土过渡区密实化、改善孔结构的作用，从而增强机制砂混凝土的性能。 提出了水粉比和等效砂率概念及含石粉机制砂混凝土体系配合比的优化设计原理，阐述了以水灰比保证强度和以水粉比确保工作性的设计原则。更多还原

【Abstract】 The limits of micro fines content in manufactured fine aggregate (MFA) stipulated in current standard are still disputed and restrict application of MFA and rational utilization of micro fines. On the basis of analyzing characteristics of MFA and micro fines, effects of micro fines on properties of cement and concrete are studied and limits of micro fines content in MFA for concrete are discussed in this dissertation. Characteristics of preparation of MFA concrete and an optimized mix design philosophy for concrete system with MFA containing micro fines are also proposed. Furthermore, the effecting mechanisms of micro fines on MFA concrete are analyzed.Main characteristic parameters of MFA and micro fines and regression relations between these parameters were statistically investigated through analyzing 57 samples. The investigation reveals the interrelation between fineness module and 2.36 mm sub-tailing. The particle shape parameters of MFA were studied through DIP technology and interrelations between these parameters and roughness measures are discussed. Interrelation between bulk density and micro fines content, and interrelation between methylene blue value and content & earthiness of clay are studied. Particle-size distribution of aggregate micro fines was tested by laser granulometer.Effects of micro fines on various cements and effects of different micro fines on cements including those blended various additions are researched in aspects of water demands of standard consistence, setting times and strength when substituting micro fines for part of cements; and consistence, strength, shrinkage and resistance to cracking of mortar are also researched when substituting micro fines for part of sand.The effects of micro fines on properties of concretes are researched. The interrelations of best workability and optimum water/powder ratio are discussed and the concept of bleeding latency time and its correlation with bleeding ratio are described. For MFA with poor gradation, the micro fines can improve workability of concrete. The compressive strength, flexural strength and drying shrinkage increase with micro fines content, and go down after the maximum. Both axial compressive更多还原