The Strength Prediction And Durability Research Of High Performance Concrete With High Iron Titanium Metakaolin

High iron titanium metakaolin is a sheet and highly active mineral admixture composed of low grade and high iron titanium kaolin calcination at certain temperatures.But it's not conducive to the production and transportation because of the light quality and large specific surface area.Study the application of composite mineral materials compounded by high iron titanium metakaolin,fly ash and slag in concrete is of great economic efficiency and social significance for promoting the high iron titanium metakaolin utilization and application in practical engineering.First,compared the influence of high iron titanium metakaolin and its composite modification to the cement.The results show that: Metakaolin can increase the cement standard consistency water consumption,and reduce the cement net fluidity,fluidity of mortar,initial and final setting time.Metakaolin has a great impact on the adaptability of cement and the poly carboxylic acid water reducing agent.Composite mineral materials can improve the effect of the cement performance caused by the pure high iron titanium metakaolin.Composite mineral materials is not conducive to the improvement of cement mortar early activity,but can obviously improve the activity of the late,and the enhancing effect on maximum when the dosage is 15%.The activity index of composite mineral materials greater than that of the pure high iron titanium metakaolin under the same content in the curing late.Second,Two prediction models of the multiple linear regression equation and the type of 8-17-1 BP neural network based on the L-M algorithm were set up respectively to predict the compressive strength of metakaolin high-performance concrete.The study found that: the BP neural network prediction model has high prediction accuracy and its predicted results is reliable.The fitting values of the predicted and measuredcompressive strength for 3d and 28 d is 0.976 and 0.997 respectively.The BP neural network prediction model can be used to predict the high iron titanium metakaolin high-performance concrete compressive strength,and it has good guidance for actual production and engineering application.Again,composite mineral materials and pure metakaolin were studied on the influence of workability,strength and durability of high performance concrete according to the principle of orthogonal.Experimental results show that: 1)the workability of concrete decrease with the increasing dosage of metakaolin.Composite mineral materials can alleviate this adverse effects caused by only mixing the pure metakaolin due to the composite superposition effect;2)Composite mineral materials is less than pure metakaolin admixture on promoting the early strength of concrete.When curing age to 28 days,composite mineral materials on the enhancement of concrete compressive strength higher than that of only mixing pure metakaolin with the same dosage.The compressive strength mixed 15% composite mineral materials increased by 28.4% compared the concrete without metakaolin,and increased by 5.3%compared with only mixing 15% pure metakaolin concrete;3)Metakaolin can improve the durability performance of the concrete.The chloride ion penetration resistance and frost resistance performance of concrete are greatly improved with the dosage of metakaolin increasing.Composite mineral materials on improvement the durableability of concrete much large than adding pure metakaolin with the same dosage.The electric flux through concrete specimen reduced by 86.9% and 82.7% with the metakaolin content is 15% when mixed with composite mineral materials and pure metakaolin admixture respectively,and the specimen freeze-thaw cycle number increased by61.3% and 44.4% respectively.Metakaolin has significantly effect on the reduction of electric flux and the improvement of the freeze-thaw cycles for high performance concrete.Finally,considering from the economy,workability,strength and durability of the metakaolin high-performance concrete,the function value is 0.92 with the content of fly ash and slag are all 10% by using the method of objective weight,which is the maximum of 16 group.And other various one-way index also composite demand.Therefore,it is the optimization of concrete mix proportion parameter.The durabilityof high iron titanium metakaolin high performance concrete has been further improved after the composite modification of fly ash and slag.It can improve the service life of the concrete project doped with the high iron titanium metakaolin,especially the major infrastructure projectss which have higher requirements for durability.