Study On The Properties Of Reactive Powder Concrete With Ultrafine Slag

Reactive Powder Concrete (RPC) is a new kind of high performance cement composite materials, which is in high strength, high toughness, high durability and high volume stability. RPC has a very prominent advantage than common concrete. Because of the high cost, RPC materials are rarely used in the actual engineering, except in some special structure. Silicon fume, quartz-sand and steel fiber in the raw materials of RPC are all expensive. And the most expensive material is steel fiber. At present people still cannot find any cheaper fiber materials to take the place of steel fiber. Therefore, with the ultrafine slag instead of silicon fume, if the property of RPC may not become bad, there will be very vital significance for RPC used in great quantities in engineering.First, this article studies the optimum ratio among the cement, ultrafine slag, quartz-sand by the orthogonal test. Second, we obtain the optimal ratio between the two particle sizes of quartz-sand. Third, through six groups of experiment, we find the best volume content of steel fiber. Finally, we succeed in producing the reactive powder concrete with ultrafine slag which meet the standards. In all groups, the compressive strength can reach to a high point with the number approximately 150.3MPa, and the most strength of flexural is 30.2MPa.On the basis of the optimum ratio, this article discusses the relationship between the property of RPC and curing systems which contain with mould or without mould, the rate of temperature, constant curing temperature and constant curing time in the process of curing. The experimental results show that specimens with mould or without mould in the process of curing can reach to the strength of the related requirement of the design, the rate of temperature which is too fast will reduce the strength of RPC. When constant curing temperature over 70℃and other conditions remain unchanged, the compressive strength of RPC can be up to 130 MPa and the flexural strength can be up to 18 MPa. When constant curing time over 36h and other conditions remain unchanged, the compressive and flexural strength of RPC can also meet the related requirement of the design.In addition to the curing systems in the influence of the property of RPC, this article also studies the RPC's ability of the resistance of the chloride permeability and the freezing-thawing damage. The experimental results show that the quantity of electric charge through RPC specimens during 6h is 42.53C. So the permeability of RPC specimens can be ignored. After the number of the freeze-thaw cycle over 300 times, relative dynamic elastic modulus of RPC reduce to 90.3%, quality loss ratio is almost zero. Therefore, with the ultrafine slag instead of silicon fume, the RPC has excellent impermeability and frost- resistance.