An Experimental Study On Pre-placed Recycled Aggregate Concrete Cast By Grout Impregnation Method

In China0.1to0.2billion tons of abandoned concrete are produced each year owing to various construction activities. Most of these wastes pile up in the garbage dump field. The transportation of these wastes causes secondary pollution and the destruction of the ecological environment. Recycled aggregates have been used as a replacement of natural aggregates for many years. The huge potential benefits can be obtained from the use of recycled aggregates. This not only reduces the amount of abandoned concrete discharge and secondary environmental pollution, but also decreases the consumption of natural gravel and protects natural resources and the human-life supporting environment. Therefore, good economic, social and environmental benefits will be expected. The most valuable treatment method of abandoned concrete is to generate building materials as a renewable resource. Therefore, it is necessary to study the physio-mechanical properties of recycled concrete.An experimental study is conducted in this thesis on pre-placed recycled aggregate concrete cast by the grout impregnation method. At different water/cement ratios, aggregate volume fractions, sand ratios and admixture contents, recycled concrete samples are cast by the grout impregnation method. The cubic compressive strength, the flexural tensile strength and the properties of abrasion resistance, frost resistance and anti-permeability are experimentally measured. Experimental results show that, compared with concrete cast by the traditional mixing technique, the strength of concrete cast by the grout impregnation method is influenced by more factors. At the same conditions, recycled aggregate concrete is of lower strength and worse durability than natural aggregate concrete. If appropriate aggregate gradation, water/cement ratio, fine aggregate and admixture are selected, the mechanical properties and durability of recycled concrete will be improved greatly. The strength of recycled concrete increases with the increase of the natural aggregate content, but decreases with an increase in water/cement ratio. Compared with natural aggregate concrete, the recycled concrete is of lower abrasion resistance and anti-permeability and is not recommended to use in cold regions. These conclusions can provide references for the application of recycled concrete.