Study On Preparation And Mechanical Properties Of Active Iron Tailings Concrete

Reactive powder concrete(RPC)is a kind of cement-based composite material prepared by mixing silica fume,cement,quartz sand,quartz powder and steel fiber.As a building material with high strength and high durability,its material cost is one of the key problems whether it can be popularized and used.In order to reduce the economic cost of RPC,this paper uses iron tailings of different particle sizes to completely replace quartz powder and partially replace quartz sand to prepare iron tailings RPC,and studies its basic mechanical properties,sulfate corrosion resistance and frost resistance.This paper mainly includes the following research contents:(1)Part of quartz sand was replaced by iron tailings,and quartz powder was replaced by400-mesh iron tailings powder.The basic mechanical properties of each group of specimens were tested by orthogonal test method,and the water-binder ratio,silica fume content,and iron tailings sand replacement rate were studied.Compared with the different effects of iron tailings powder content on iron tailings RPC,regression analysis was performed based on the test data,and the fitting model of iron tailings RPC on the above performance was given.The research shows that the water-binder ratio has the greatest influence on the strength of iron tailings RPC.Compared with the compressive strength,flexural strength and splitting tensile strength of the water-binder ratio 0.24 group of specimens,the water-binder ratio of 0.20 group of specimens has the greatest impact.The performances are improved by 13.52%,117.35%and 42.20% respectively.(2)The sulfate corrosion resistance test was carried out on iron tailings RPC to study the corrosion effect of sulfate on each group of specimens under different erosion conditions.Compressive strength degradation model of iron tailings RPC under erosion conditions.The research shows that when other conditions are the same,in the range of silica fume content of20%-30%,iron tailings RPC with silica fume content of 25% has the best anti-sulfate corrosion resistance,and the compressive strength loss under 60 d long-term soaking conditions Compared with the conventional RPC,the iron tailings RPC has better anti-sulfate corrosion resistance,and the compressive strength loss rate of the conventional RPC is reduced by 0.25%under the condition of 60 d long-term soaking.(3)The freeze-thaw cycle test of iron tailings RPC was carried out by the quick freezing method,the effect of silica fume content on its frost resistance was studied,and the frost resistance performance of iron tailings RPC and conventional RPC was compared.The model curve is in the form of a power function,and a damage model of the relative dynamic elastic modulus of iron tailings RPC is established.The test results show that when other conditions are the same,within the range of 20%-30% silica fume content,the iron tailings RPC with silica fume content of 25% has the best antifreeze performance,and the relative dynamic elastic modulus under 200 freeze-thaw cycles is the best.The loss rate is 7.76%;compared with conventional RPC,iron tailings RPC has better antifreeze performance,and the loss rate of relative dynamic elastic modulus under 200 freeze-thaw cycles is 1.71% lower than that of conventional RPC.