【作者】 彭艳周；

【导师】 胡曙光；

【作者基本信息】 武汉理工大学 ， 建筑材料与工程， 2009， 博士

【摘要】 活性粉末混凝土(RPC)是一种具有高力学性能和优异耐久性的高性能水泥基复合材料,应用前景非常广阔。本论文针对当前RPC材料研究与应用中所存在的成本高、能耗大的突出问题,采用钢渣粉、超细粉煤灰等作为活性组分并用细河砂代替石英砂,进行钢渣粉RPC的研究。通过对钢渣粉RPC的物理力学性能、耐久性能和水化硬化及微观结构的系统研究,揭示了钢渣粉RPC组成、结构与性能之间的相互影响和变化规律,掌握了钢渣粉RPC的设计方法与制备技术,为钢渣粉RPC材料的制备和推广应用提供了重要参考。本文进行的主要研究工作和取得的重要成果如下:从材料的实际应用目的出发,根据发展战略、技术要求和经济性三方面的综合考虑,指出钢渣粉RPC的设计思路为:设计制备的钢渣粉RPC应具有“高强度(抗压强度200级)、优异的耐久性及良好的经济性和环境相容性”特点;依据中心质理论建立了钢渣粉RPC微观结构的理想模型。在此基础上,提出了钢渣粉RPC的设计方法:(1)材料组成设计上,使用钢渣粉、超细粉煤灰和硅灰等掺合料作活性组分,并运用灰色关联度分析法进行钢渣粉颗粒级配的优化,提高颗粒群的水化活性;(2)材料密实度设计上,一方面运用最紧密堆积理论进行钢渣粉RPC的配合比设计,以提高钢渣粉RPC复合体系的堆积密实度,另一方面使用与复合体系相容性良好的高效减水剂,降低体系水胶比,以提高浆体密实度。运用以上设计方法,利用复合体系中不同材料特性与颗粒尺度的活性差异,通过颗粒群的有序次第水化,实现RPC复合体系的动态水化填充和静态密实堆积,形成结构良好的水泥石微观结构,以期获得高性能的钢渣粉RPC。基于最紧密堆积理论的钢渣粉RPC配合比优化设计,通过Matlab和Microsoft Excel分析方法进行规划求解实现,主要有如下四个步骤:首先,根据粉体学工程原理,确定适用于RPC的Dinger-Funk方程中分布模数n的取值;其次,由各原料组分的颗粒分布曲线,选定RPC配合比求解问题的目标值和调节值;第三,根据原料等实际情况设定配合比求解问题的相应限制条件;最后,运用Matlab和Microsoft Excel程序进行优化求解。采用浆体最小需水量试验和配合比正交设计试验对设计结果进行了验证。通过化学组成、比表面积及养护温度对钢渣粉胶凝性能影响的研究,以及钢渣粉掺量、比表面积对RPC力学性能影响的研究,运用灰色关联度分析法对钢渣粉及其颗粒级配进行优选和优化,以提高RPC性能;研究了水胶比、砂胶比及钢纤维掺量等配比参数对RPC力学性能的影响;系统研究了热养护制度对RPC力学性能和微观结构的影响规律。掌握了高性能钢渣粉RPC的制备技术,使用总掺量为42%～48%(胶凝材料质量)的钢渣粉复合矿物掺合料及其他原料,在合适的成型养护工艺下制备出高耐久性的200级钢渣粉RPC材料。运用XRD、IR、综合热分析(TG-DTG-DSC)、SEM-EDXA、显微硬度、纤维拔出试验与孔结构分析等测试手段,系统研究了钢渣粉RPC的水化硬化机理与微观结构,探明了其微观结构形成过程和结构特征,揭示钢渣粉RPC优异的力学性能和耐久性的根本原因是:钢渣粉RPC体系较高的堆积密实度和极低的水胶比,硅灰、钢渣粉和超细粉煤灰等活性组分的次第水化效应和密实填充效应的有效发挥,钢纤维的阻裂、增强和增韧作用。更多还原

【Abstract】 Reactive powder concrete (RPC), otherwise known as high-performance concrete, has high durability and excellent mechanical properties, so the application of RPC has good prospects. In this paper, aiming at the main problems in application of RPC, i.e., high production costs and energy consumption, steel slag powder (SS) and ultra-fine fly ash (UFFA) were used as reactive powder component to product RPC, and meanwhile, fine river sand was used as aggregate instead of quartz sand. Based on systematic study of the physical and mechanical properties, durability, microstructure and hydration as well as hardening of RPC containing SS, the relationship among the composition, structure and performance of RPC containing SS was revealed and the design methods and preparation technology for RPC containg SS were grasped, which provided important references for preparation and application of RPC containing SS.The main research and achievements accomplished in this paper are as follows:In order to propel the application of RPC, taking three aspects, i.e., development strategies, technical requirements and economy of material into account, it was pointed out that the design of RPC containing SS must flollow the principle that RPC prepared in this paper should have high strength (RPC 200), excellent durability, good economy and environmental compatibility. Based on the centroplasm theory developed by Wu ZhongWei, the ideal microstructure model of RPC containing SS was built, which provided theoretical guidance for design and preparation of RPC. On this basis, the design methods of RPC were proposed: In the component design, compound mineral admixture containing SS and UFFA was utilized as reactive powder component and the particle size distribution (PSD) of SS was optimized by gray correlation method in order to improve the hydration activity of SS; in the dense microstructure design, on one hand, a mix design method based on the maximum density theoretical model (i.e., Dinger-Funk equation) was developed in order to enhance the packing density of compound system of RPC containing SS, on the other hand, superplasticizer having good compatibility with compound system was utilized to reduce the water-cement ratio of compound system and thus to increase the paste density. By the design methods mentioned above, dense microstructure of cement paste could be formed through dynamic hydration filling effect and stastic dense packing effect of the compound system, which were brought out by ordered hydration owing to the different hydration activity of mineral admixture particles with different chemical compositions and particles size. Therefore, RPCs with high-performance would be obtained.The mix design based on the Maximum Density Theoretical Model was carried out through Matlab and Microsoft Excel 2003, which had the following 4 steps: Firstly, the value of distribution modulus, n, in Ding-Funk equation sutiable for RPC was chosen according to some principles of powder engineering; secondly, the target and adjustable value of mix design was defined on the basis of particle size distribution (PSD) of each raw material; thirdly, the constrains were determined according to the circumstances; Finally, an optimization algorithm is programmed in Microsoft Excel and Matlab. The mix proportion of RPC obtained by this method was verified by experimental programs for minimum water requirement of paste and orthogonal experimental design for RPC.The influence of chemical composition, specific surface area and curing temperature on hydration activity of SS and the effect of the amount of and specific surface area of SS on mechanical properties of RPC were studied. The effect of PSD characteristics of SS on mechanical properties of RPC was analysed by gray correlation method. Based on these findings, the PSD of SS would be optimized in order to improve RPC performance. Moreover, the influence of water cement ratio, sand-cement ratio and steel fiber content on mechanical properties of RPC was researched and the effect of heat-curing regime on both mechanical properties and microstructure of RPC was analysed systematically. Therefore, the preparation technology for high-performance RPC containing SS was grasped. RPCs with excellent-durability as well as high mechanical properties were prepared by utilizing 42%～48% (by weight of binder) compound mineral admixtures, which included SS, silica fume and UFFA, and other raw materials and through curing in a proper heat-curing procedure. The hydration, hardening mechanism and microstructure were systematically studied through XRD, IR, thermal analysis (TG-DTG-DSC), SEM-EDXA, micro-hardness, steel fibers pull-out test and pore structure analysis. Therefore, the process of microstructure forming and structural characteristics of RPCs containing SS were discovered and the excellment mechanical properties and high durability of RPCs containing SS resulted from 3 aspects: the higher packing density and very low water-binder ratio of RPCs; the static dense packing and dynamic hydration filling effect of the compound system, which included silica fume, SS and UFFA; the cracking resistance, enhancing and toughening effect of steel fibers in RPCs.更多还原