新拌水泥沥青浆体的流动性及显微结构研究

Investigation on Flowability and Microstructure of Fresh Cement Asphalt Binder

研究了乳化沥青对新拌水泥沥青浆体流动性和显微结构的影响;分析测试了添加不同类型及不同掺量的乳化沥青后新拌浆体的流动性(扩展度)及水化热;采用光学显微镜原位观察了分散体系显微结构的形成及演化过程.结果表明:乳化沥青的加入可大大提高浆体的流动性和流动保持性,同时可延缓水泥水化进程;随乳化沥青掺量的增大,浆体流动性先增大后降低,流动保持性逐渐增强,诱导期逐渐延长;阴离子乳化沥青对浆体流动性和流动保持性的改善及其对水泥水化的延缓效果较阳离子乳化沥青更为显著;浆体显微结构的形成及演化包括乳化沥青颗粒对水泥颗粒的吸附、乳化沥青破乳同时伴随水泥水化等几个过程,最终形成水泥、水化产物和沥青膜互穿的有机-无机复合结构.

Influence of asphalt emulsion on the flowability and microstructure of fresh cement asphalt binder was investigated.The spread diameter of fresh cement asphalt paste with different asphalt content and type was measured.Optical microscope was used to observe the formation and evolution of the microstructure.Results show that the flowability and flow retention of the paste were significantly improved,and the time to reach peak temperature of hydration curve was delayed obviously.As the asphalt content increased,the flowability became better at first but got poorer then.The flow retention was enhanced and dormant period increased.The effect of anionic asphalt emulsion on the flowability,flow retention and microstructure was more obvious than cationic asphalt emulsion.It was proved from direct observation on fresh cement asphalt paste by optical microscope that the evolution process of microstructure included three stages：the adsorption of asphalt particles on the cement grains,the demulsification and film-forming of asphalt particles as well as the hydration of cement.The final interpenetrating composite structure was composed of hydration products and asphalt film.