基于骨料功能化提升现代混凝土体积稳定性研究

Volume stability is most important to improve the durability of modern concrete, which is a main research content for high performance concrete and is also an urgent unresolved problem. The majority of published researches concentrated on the effect of cementitious materials on the volume stability of concrete, while relatively less is the related researches based on aggregate characteristics. In this project, in terms of principles of the temperature or/and moisture deformation of concretes, characteristic parameters of functional aggregate are designed. The functional aggregate with low thermal expansion coefficients（＜5.0×10^(-6)/℃）, high elastic modulus（＞28GPa）, porosity water absorption and interlocking type surface morphology will be prepared.The effect is analyzed of functional aggregate characteristics on the volume deformations of concrete under single and coupling impact of temperature and moisture, and mapping relations between the volume deformations of concrete and the aggregate characteristics are established.The mechanisms are explored of functional aggregate characteristics upon moisture control, matrix phase constraint and thermal deformation of concrete. Based on theories of heat and moisture transfer in porous medium, the process of hygro-thermal coupling deformation of concrete is numerically simulated. It would be revealed how the functional aggregate characteristics enhance comprehensively the volume stability of modern concrete, and a new way is proposed for research and development of concrete with high volume stability, and theoretical guidance is provided for preparation and the choice of aggregates with different characteristics and its efficient application in high performance concrete.

提升混凝土体积稳定性是提高现代混凝土耐久性、实现高性能化的重要研究内容，也是亟待解决的关键问题。已有研究大多集中于水泥石对混凝土体积稳定性的影响，而基于骨料特性的影响研究较少。本项目依据混凝土温湿度变形原理，设计功能型骨料的特性参数，研究制备具有低热膨胀系数（＜5×10^(-6)/℃）、高弹性模量（＞28GPa）、多孔吸水和表面嵌锁形态等特性的功能型骨料；研究功能型骨料特性对温湿度单一及耦合作用下混凝土体积变形的影响规律，建立功能型骨料特性与混凝土体积变形的映射关系；研究功能型骨料特性对混凝土湿度调控、基体相约束限制和温度变形的影响机制，依据多孔介质湿热传输理论，对混凝土湿热耦合变形进行数值模拟，全面揭示功能型骨料综合特性提升现代混凝土体积稳定性的作用机理。为高体积稳定性混凝土的研究与开发提供新思路，为选择和加工制备不同特性的骨料及其在混凝土中高效应用提供理论指导。

提升混凝土体积稳定性是提高现代混凝土耐久性、实现高性能化的重要研究内容，也是亟待解决的关键问题。传统观念认为混凝土体积变形主要受制于胶凝材料，而对用量最大的骨料却研究甚少。事实上，骨料特性是影响混凝土体积稳定性重要因素之一。本研究借鉴烧胀型高强陶粒的膨胀模式理论和堇青石基复合功能陶瓷的制备理论，以煤矸石和粉煤灰等硅铝质工业废弃物为主要原料、选用白云石粉、碳酸钙、橡胶颗粒和碳粉等作为发泡剂，通过配比优化和工艺设计，设计制备出了具有低热膨胀系数（＜5.0×10^(-6)/℃）、高单颗粒抗压强度（＞4.5MPa）、多孔吸水和表面嵌锁形态等特性的功能型骨料。掌握了利用硅铝质工业废弃物（煤矸石、粉煤灰和镍渣等）为主要原料设计制备功能型骨料的关键技术与方法。研究了功能骨料特性对混凝土体积稳定性的影响，阐明了功能型骨料特性与混凝土体积稳定性的映射关系。探究了功能骨料特性提升现代混凝土体积稳定性的作用机理。揭示了多孔功能型骨料的内养护效应对混凝土内部湿度调控及界面增强的影响机制，低热膨胀系数的功能型骨料对混凝土温度变形的调节机制，表面嵌锁形态的功能型骨料对混凝土基体相的约束限制机制。研究成果为高体积稳定性混凝土的研究与开发提供了新思路，为选择和加工制备不同特性的骨料及其在混凝土中高效应用提供了理论指导。