Preparation and properties of gradient structure concrete member

Based on the dense packing powder theory, the refining and self-healing principles, and hydrophobic treatment, the special surface-layer materials and design are proposed in gradient structure concrete (GSC) member. According to service behavior, the GSC member is divided into serial structure and parallel structure. And it is fabricated corresponding to structural parameters by stacked press process, or pulled clapboard method, or suspended nets method. Use of small and full scale specimens for testing, the results are shown that: 1) the surface-layer strength of the GSC component improved by 30%, compared to that of a conventional single-layer component; 2) the width of the crack ranges from 0 to 0.1mm in the GSC component, whereas a conventional single-layer component are distributed with visible cracks(0.2-0.5mm); 3) The permeating depth and chloride diffusion coefficient of the GSC component is respectively 0mm and 6.3×10-13 m2/s, whereas a conventional single-layer component is 15mm and 12.8×10-13 m2/s.