Foundational Properties And Applications On Recycled Powder

In the past few years, the waste concrete from the demolition of buildings sharply increases, with the acceleration of urbanization and the construction process of small towns as well as the progress of industrial and civil building update and the increasing scale of municipal relocation. In comparison with developed countries, investigation on recycled concrete has started relatively later in China, however, there are still some good results. High-quality recycled coarse and fine aggregate are obtained by strengthening treatment, and most properties are close to natural aggregate. Nevertheless, large numbers of powder composed of concrete's scraps are produced during the procedure of recycled aggregate strengthening treatment, we call them recycled powder. New waste and pollution will be generated if the powder is not effectively used.The present research is based on National "No. 11 five years plan" technological supporting project (2006BAJ02B0504). The main content includes as the following: 1), basic performance of recycled powder; 2), the influences on concrete by recycled powder and superfine recycled powder; 3), the influence of recycled powder on strength and workability of mortar; 4), the influence of recycled powder and other industrial residue include the residue and fly ash of refinery coke on strength of autoclaved brick.The experimental results indicate that recycled powder is loose and porous construction waste powder, its hydrated activity is close to that of fly-ash when the content is small. The hydrated activity can be significantly improved after superfining or heat treating. Recycled power shows negative effect on workability of concrete and mortar, while the strength are not considerable reduced when its content is no more than 20%. When the content is 10%, it offers an improved chloride osmosis resistance. Strength, especial the early age strength can be improved by the superfine recycled powder and the effect is better than silica fume, meanwhile, the long term strength is not damaged.Recycled powder is capable to replace cement to make mortar and exhibit a certain of activity with the content lower than 20%,that can reduce cost and save cement. Recycled powder, residue and fly ash of refinery coke as binder material are appropriate to manufacture autoclaved brick and it has higher strength under the autoclave cure condition.