Investigation of using recycled powder from waste of clay bricks and cement solids in reactive powder concrete

• Use of the recycled powder from construction and demolition wastes in RPC is studied.
• Environmentally-friendly and cost-saving RPC mixtures with high performance are developed.
• Natural sand can be used instead of crushed quartz in the green RPC mixtures.
• Mix proportions of the green RPC are studied through theory and designed experiments.

Recycled powder, produced from the construction and demolition wastes, contains unhydrated cement particles. It can reduce environment pollution to use recycled powder as a cementing material. It is investigated to use recycled powder to partially replace silica fume or cement in Reactive Powder Concrete (RPC) to develop environmentally-friendly and cost-saving RPC mixture with high performance. Properties of the recycled powder are tested firstly. And according to maximum packing theory, the RPC mix with the recycled powder is designed. Influences of the fine aggregate, quartz and natural sand, on the RPC are investigated. The water-cementitious materials ratio (w/cm) for RPC mixes with the recycled powder are studied and selected. The recycled powder is used to replace the silica fume and cement in RPC respectively, and influences of the replacement ratio on the flowability, strength and durability are investigated. The standard curing is used for all the tests instead of steam curing normally required for RPC. Considering the flowability, strength, durability, cost and environmental savings, it is suggested that the recycled powder can be used to replace the silica fume and cement in RPC partially, and natural sand can be used instead of quartz. Additionally, influences of GGBFS powder on RPC mix with the recycled powder are investigated.