纳米非晶态水化硅酸钙接触硬化胶凝性能研究

Research on Contact-hardening Cementitious Properties of Nano-amorphous Calcium Silicate Hydrate

不同于传统水泥基材料水化硬化特点,本研究旨在探讨纳米非晶态水化硅酸钙(C-S-H)的接触硬化胶凝性能.分别采用了两种不同来源的C-S-H粉体,对其在20~60MPa压力下恒压3min进行压制成型,测定成型试件的表观密度和力学性能,并结合成型前后微观结构的变化探讨C-S-H的接触硬化胶凝机理.结果表明,纳米C-S-H具有良好的接触硬化胶凝性能,能在几分钟时间内制备出轻质高强试件.表观密度约为800kg/m3的试件,其抗压强度可达20~30.5 MPa.微观结构表明,C-S-H颗粒在外力作用下发生粘性流动而使颗粒间距减小至引力范围并发生接触,颗粒的细化和塑性变形促进了结构键的生成,从而使试件具较高强度.

Different from the known setting and hardening properties of cementitious materials, this study focuses on the eontact-harderiing properties of nano- amorphous calcium silicate hydrate （C-S-H）. Two different types of C-S-H powders were used. The powders were compressed under 20-60 MPa for three minutes to produce compacts. Bulk density and compressive strength of the compacts as well as the microstructure of C-S-H before and after compaction were measured. The results show that nano C-S-H presents excellent contact-hardening cementitious properties. Lightweight and high strength compact can be produced by compression in several minutes. When the bulk density of the compact is about 800 kg/m^3, compressive strength can be up to 20.0-30.5 MPa. According to the microstructure analysis, the distance of C-S-H particles is reduced during compaction because of the viscoelastic flow. Therefore, the particles become contact to each other,and attractive force between particles is formed. Furthermore,fragmentation and plastic deformation attributes to the compression pressure, leading to the formation of cohesion and ad- hesion structure. Consequently,the compressive strength of the compacts is greatly improved.