Study On Reactive Powder Concrete With Natural Siliceous Admixture

Reactive powder concrete (RPC), with ultra-high strength, low brittleness and excellent durability, has a good prospect of engineering application. But its high preparation cost and strict preparation technology limit its application in the practical engineering. In this paper, the reactive powder concrete with good performance has been designed and prepared out through the silica fume partical replaced by silica powder which, introduced as a new natural active siliceous mineral admixture, can be considered the sixth component of RPC. As low-cost of silica powder and simple production process of RPC, It has a certain positive effect on the promotion for engineering application of RPC.In this paper, firstly, the pozzolanic effect and water demand of silica powder has been simply studied. And then, the preparation design of RPC with silica powder has been mainly studied through experiment. Finally, based on the results of experiment above, the dimensional stability, mechanical properties and durability of RPC have been studied. The results show that:(1) Silica powder can improve the workability of RPC well when water-cement ratio is 0.22 and 40% silica fume is replaced by silica powder. The flowability of RPC paste can be enhanced to 163mm, and the compresstive strength and bending strength prepared in 28d of RPC prepared can get to 128.6MPa & 20.90MPa separately. (2) The content of steel fiber has a significant effect on enhancing toughness of RPC. When the volume content is 2～3%, the bending strength prepared in 28d of RPC can increase 5 MPa with good workability. (3) The curing condition of RPC has a significant effect on the development of strength. The performance of active mineral additives under heat curing is better than that under standard curing. The strength of RPC increases well and has little effect on the development of later strength. (4) The RPC prepared in this paper can grain a good dimensional stability and durability under heat curing. The shrinkage in 120d of RPC with silica powder is(250～300)×10-6 and the results of experiments for permeability resistance, frost resistance and resistance to sulfate corrosion are well. At the same time, the economic analysis for production costs of RPC with silica powder has been studied and its application to high-speed passenger transportation special line has been realized successfully. The author points out that the silica powder has a good prospect of engineering application and a positive meaning for the promotion for engineering application of RPC.