The Study On The Resource Recovery Of Construction Waste For Recycled Aggregate Concrete

In our country, urban construction waste production has increased with Urbanization. It’sreasonable resource utilization for these “urban mining” has achieved everyone’s consensus. Atpresent, there are a lot of researches and applications on the recycled aggregate concreteproduced by recycled concrete aggregates, and the waste concrete was sorted out from theconstruction waste and then processed into recycled concrete aggregates. However, in the actualprocess, construction waste sorting is more difficult and requires relatively high cost. In view tothis situation, we chose the construction waste as the research object, which contains a variety ofcompositions, such as waste concrete, waste brick, waste mortar, waste ceramic and waste glass.In order to help the actual production, the construction waste recycled aggregates and itspreparation of recycled aggregate concrete were systematically studied. The followingconclusions were drawn from these works:(1)When the coarse aggregate concrete and fine aggregate concrete designed strength gradewas C30.The maximum replacement ratio of recycled coarse aggregates was50%in the recycledcoarse aggregate concrete and recycled fine aggregates was20%in the recycled fine aggregateconcrete.(2)The performance of recycled aggregate concrete which was prepared by50%recycledcoarse aggregates and20%recycled fine aggregates were lower than the recycled aggregateconcrete, which was prepared by50%recycled coarse aggregates or20%recycled fineaggregates. To compare with the normal concrete, it’s28d compressive strength was reduced by28.9%, wear loss was higher than0.305g/cm2, compressive strength loss rate was higher than4.9%and splitting tensile strenrth loss rate was higher than3.8%when eroded by sulfate.(3)When using chemical slurry to strengthen recycled coarse aggregate, the slurry when mixedwith rice husk ash has a better strengthening effect for recycled coarse aggregates.(4)When using the construction waste recycled coarse aggregates for the preparation of highstrength recycled coarse aggregate concrete, the workability of fresh concrete was better thannatural aggregate concrete, but its mechanical properties and durability was lower than naturalaggregate concrete. Its28d compressive strength of recycled coarse aggregate was61.9MPa thatmet the designed strength requirement. The construction waste for preparation of high strength concrete was feasible.(5)The fluidity of recycled mortar, which was prepared with construction waste recycled fineaggregates, decreased and then increased with the increase in replacement rate of recycled fineaggregates.And the mechanical strength of recycled mortar decreased with the increase inreplacement rate of recycled fine aggregates. To compare with the normal mortar, when riversand was completely replaced by recycled fine aggregates in the mortar, it’s28d compressivestrength was reduced by51%and flexural strength was reduced by37.6%.(6)When construction waste recycled powder as mineral admixtures used to replace cementfor preparing recycled mortar, the more powder in the small size of the particles that recycledmortar has reduced fluidity and increased the degree of mechanical strength.(7)The C30recycled coarse aggregate concrete were crushed into recycled coarse aggregates.Using the secondary recycled coarse aggregates for preparation of recycled coarse aggregateconcrete and the designed strength was C30, its workability of fresh concrete, mechanicalstrength and durability were better than one-time recycled aggregate concrete. Using thesecondary recycled coarse aggregates for preparation of high strength recycled coarse aggregateconcrete, its workability of fresh concrete and durability were better than one-time recycledaggregate concrete, but the mechanical strength was lower than one-time recycled coarseaggregate concrete.(8)Using the construction waste which contains a variety of compositions for preparation ofrecycled aggregate concrete was feasible and it was feasible to realize the multiple circulation ofrecycled coarse aggregate concrete.