定向冷冻法制备层状水泥基材料.docVIP

 Laminate cement-based materials fabricated using directionally freeze-cast method# Wan Keshu, Xue Xiaobo, Sun Wei* 5 10 15 20 25 30 35 40 (School of Materials Science and Engineering, Southeast University, NanJing 211189) Abstract: One of the main disadvantages of cement based-materials is the suddenly failure caused by the brittle nature of the materials, so it is important to increase the toughness, or ductility, of cement-based materials. In this research, the concept of laminate cement-based materials was proposed to improve material toughness. Laminate Poland cement-based materials with different water cement ratios and different freeze temperatures were fabricated using directionally freeze-cast method. Characterizations of SEM and X-ray CT were performed. Microscopic results showed the ordered laminate microstructures with layer thickness of tens to hundreds micrometers. Besides, crack deflection phenomena observed on the fracture surface showed the potential of laminate cement-based materials to increase toughness. Keywords: cement-based materials; laminates; directionally freeze-cast; microstructure 0 Introduction Cement-based materials are one of the most important construction materials in the word. Considering the brittle nature of cement based-materials, it is very import to increase the toughness, or ductility, of these materials. There are a number of ways to effectively increase ductility, such as to fabricate cement composites using stronger fibers or softer organic materials. For material science, tailing microstructure is widely applied to improve property, which means to improve the ductility from the cement-based materials itself. It is accepted that nature materials, such as nacre, bone etc., have great toughness because of its laminate structure [1,2], and a lot of nature mimics materials, such as laminate ceramics, were fabricated with high toughness too [3-5]. In recent years, directionally freeze-cast method to prepare laminate mater