| Concrete engineering buildings in the marine environment will be eroded by chloride ions and sulfates in seawater,resulting in a greatly shortened service life.In order to improve the service life of concrete projects,this topic takes solid waste resource utilization as the background,based on the urgent needs of marine engineering for high-quality marine materials,especially concrete admixtures,and the practical problems of the utilization in building materials of metallurgical solid waste,marine concrete was prepared with steel slag,phosphorous slag,and slag powder,the effects of concrete admixture amount and admixture method on the workability,compressive strength,chloride-ion permeability,and sulfate resistance of the concrete were studied.The corrosion resistance mechanism of concrete admixture was analyzed by means of SEM,XRD and porosity.The main conclusions are:(1)The ternary compounding method of steel slag powder-ore powder-phosphorus slag powder can improve the chloride-ion resistance of concrete.When the total content and the amount of phosphorus slag powder are fixed,the 56d chloride-ion resistance of concrete shows a trend of first strengthening and then weakening with the increase of the ratio of steel slag powder to slag powder.When the total content of concrete admixture is 60%(the ratio of steel slag powder,ore powder,and phosphor slag powder is 1:1:1),the 56d electric flux is537 C,which makes the resistance of concrete to chloride ion penetration reaches the Grade of Q-?(500 C?electric flux Q_S<1000 C).It is concluded that the amount of phosphorus slag powder is the most important factor affecting the resistance of concrete to chloride ion penetration based on the orthogonal test and range analysis,and the chloride penetration resistance is the best when the content is 20%.It can be found that the steel slag powder-slag powder phosphorus slag powder compounding can reduce the porosity of the concrete slurry through the analysis of the porosity data of concrete slurry.The structure of steel slag powder mixed with phosphorus slag powder or ore powder is more compact compared with the blank group,which improves the chloride-ion corrosion resistance of concrete.(2)The compounding method of steel slag powder-phosphorus slag powder can improve the working performance of concrete,the strength of concrete,and the problem of reducing the resistance of concrete to chloride-ion penetration caused by the addition of steel slag powder.The strength of 28 d is 115%of that of the blank group when the total content of steel slag powder and phosphorus slag powder is 60%(the ratio of steel slag powder and phosphorus slag powder is 5:1),and the electric flux of 56 d is 1521 C,which is lower than the 1602 C of the blank group and 1814 C that of the the single-doped 50%steel slag powder group.the steel slag powder-phosphorus slag powder compounding method improves the utilization rate of steel slag powder.(3)The resistance of concrete to sulfate erosion can be effectively improved by the incorporation of phosphorus slag powder,its sulfate resistance will be reduced when the amount of phosphorus slag powder is greater than 20%.The sulfate-erosion resistance of the steel slag powder-phosphorus slag powder-slag powder ternary mixed concrete will be enhanced with the increase of the content of phosphorus slag powder and slag powder.The concrete sulfate resistance coefficient is greater than 1 during the 180 d sulfate solution erosion time,when the total concrete admixture content is 60%(steel slag powder,slag powder,and phosphorus slag powder content ratio is 1:1:1).And the seawater erosion resistance coefficient gradually increases with the erosion time,indicating that the steel slag powder-slag powder-phosphate slag powder concrete has good resistance to sulfate and seawater erosion. |
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