Experimental Study On The Performance Of Steel Slag Powder Self-compacting Concrete

Steel slag is a solid waste in the steelmaking process.Recycling of steel slag can effectively reduce energy consumption and pollution.It is found that the mineral composition of steel slag is similar to that of cement.Using steel slag powder to replace part of cement to prepare concrete can not only effectively utilize steel slag,but also improve the performance of concrete.Therefore,in this paper,steel slag powder partially replaces cement mixed into self-compacting concrete,to explore its impact on the performance of self-compacting concrete,in order to seek suitable steel slag powder self-compacting concrete ratio for engineering application.An initial mix ratio of C60 self-compacting concrete is designed in this paper.Then the influence of water reducer dosage,steel slag powder particle size and dosage on the working performance,compressive strength and flexural strength of self-compacting concrete is analyzed by single factor test.The optimal mix ratio is determined by orthogonal test and the freeze-thaw test is carried out to analyze the change rule of frost resistance performance index.The main conclusions are as follows:(1)Single factor test results show that the optimum dosage of water reducer is1.4%-1.5%,the optimum dosage of steel slag powder is 10%-15%,the optimum particle size of steel slag powder is 40-60 μm.(2)The orthogonal test results show that the working performance and mechanical properties of self-compacting concrete are greatly affected by the particle size of steel slag powder,followed by the dosage of water reducer,and the dosage of steel slag powder has little effect.When the particle size of steel slag powder is40-60μm,the dosage is 20%,and the dosage of water reducer is 1.45%,the working performance and mechanical properties of steel slag powder self-compacting concrete are the best.(3)The working performance of steel slag powder self-compacting concrete in the optimal mix proportion group meets the design requirements.The early activity of steel slag powder is low,and the 7day compressive strength of concrete is low,which is 53.8 MPa.With the increase of age,concrete performance has been significantly improved,28 d compressive strength 79.2MPa,28 d flexural strength 7.54 MPa.(4)The freeze-thaw cycle test results show that the frost resistance of steel slag powder self-compacting concrete is improved,and the mass loss rate is reduced by3.86%,the strength loss rate is reduced by 5.51%,and the relative dynamic elastic modulus is reduced by 19.05% under water freezing.Under salt freezing they are reduced by 6.44%,8.09%,20.35% respectively.Further regression analysis of the three indicators shows that when the strength loss rate is 25%,the specimen is subjected to freeze-thaw damage,and the mass loss rate is reduced by 24.3% and the relative dynamic elastic modulus is increased by 32.2% under water freezing,which is higher than that under salt freezing.