| Concrete is the most widely used material for construction and other infrastructure,which is widely used in housing construction,railway transportation,water conservancy and hydropower projects.Due to the maintenance of a large number of infrastructure projects under construction and reserve,and the transformation and reinforcement needs of the existing old buildings,the "new infrastructure and new urbanization initiatives and major projects" proposed by the state,as well as the continuous promotion of the transformation of old residential areas,the development of the western region in the new era and the integrated development of the Yangtze River Delta,will drive China to have a huge demand for concrete at present and in the future.As one of the important components of concrete,admixtures generally account for more than 20% of the cementitious materials,which also has a large demand.However,the use of slag,fly ash and other admixtures with mature technology is gradually in short supply,resulting in a certain demand gap.The guiding opinions on comprehensive utilization of bulk solid waste in the 14 th five year plan clearly put forward to improve the comprehensive utilization level of bulk solid waste and expand the utilization of steel slag and other smelting slag as admixture in construction engineering and other fields.The iron and steel enterprises in Sichuan area produce a large number of high titanium slag and steel slag which are difficult to be used on a large scale in the process of smelting iron and steel.Its storage not only occupies land resources,but also brings obstacles to the production and development of enterprises.Therefore,this paper through to potentially hydration activity of high titanium slag,steel slag,and have good promotion effect of silica fume on early strength admixture compound preparation,study the effect of its properties and applications in concrete,in order to get high-performance concrete with compound mineral admixture,to provide a reference for its application in the concrete industry,at the same time help iron and steel enterprises in smelting slag processing to realize the implementation of economic and social benefits.This thesis studied the activity of high titanium slag,steel slag,and silica fume,the basic properties such as fluidity ratio,secondly based on the law under the different ratio of high titanium slag-silica fume,steel slag-silica fume binary compound admixture and high titanium slag-steel slag-silica fume ternary composite admixture activity and fluidity ratio,explores its exothermic process,the hydration products of cement hydration and hardening cement paste pore structure,etc.,the Influence of the last study the application effect in concrete,the results showed that:(1)High titanium slag has a relatively good fluidity effect,but its activity is low.With the increase of fineness,the activity index of the high titanium slag at each age increases.Steel slag can delay cement hydration,resulting in its very low activity in the early stage and negatively affecting fluidity.However,steel slag has high activity in the later stage,with the activity index exceeding 80% at 28 days.Silica fume can increase mortar strength at each age,but the fluidity ratio will decrease to below 90% when it exceeds 5%.(2)The composite of high titanium slag and silica fume can improve each age activity index.When the silica fume mass is less than 13.3% of the composite admixture,the composite admixture’s fluidity ratio is not less than 100%.The activity of steel slag and silica fume at each age is also improved,but the activity index at 3 days is still less than 45%,and the flow ratio is further reduced.(3)The activity index of high titanium slag,steel slag,and silica fume composite is further improved than that of the dual composite admixture.When the high titanium slag(45 μm residual <12%): steel slag: silica fume is 21:5:4,the activity index reaches 80.5%,76.9%,92.5% and 99.5%,respectively,at 3 days,7 days,28 days and 90 days.The activity index at3 days can be increased based on maintaining the higher activity at the later stage.(4)Ternary composite admixture can reduce early hydration heat,when steel slag ratio16.7%,a ternary composite admixture of cement hydration delay inhibition has been diminished significantly due to the filling effect and the effect of the ash and the secondary hydration of steel slag and slag,a certain proportion of the ternary composite admixture can decrease the rate of hardened cement paste pore,improve the pore structure,increase the harmless hole ratio,formation density matrix.(5)Adding high titanium slag: steel slag: silica fume mass ratio of 16:10:4 composite admixture can make the concrete has good working performance.The strength of concrete mixed with less than 20% ternary composite admixture is higher than that of pure cement concrete.The adverse effects of high titanium slag and steel slag on the durability of concrete can be alleviated or eliminated by replacing 30% cement with ternary-composite admixture,which makes the carbonation resistance and sulfate resistance performance better than that of pure cement concrete. |
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