Experimental Research On Mechanical Properties And Frost Resistance Of Steel Slag Aggregate Concrete

All parts of our country are full of iron and steel plants of different sizes,and the output of steel slag is large and the utilization rate is low,which has become a major public hazard to environmental pollution.Steel slag can be used for concrete preparation.The mechanical properties and durability of the concrete obtained in this way are obviously improved.At the same time,it also has significant economic and social benefits for local enterprises,energy,and the environment.Because of the different production processes in various regions.The appearance,morphology,composition and content of steel slag are quite different,and the properties of concrete are also different.In this paper,the steel slag produced by Baotou Iron and Steel Group is used as aggregate to prepare concrete,and its basic mechanical properties,stress-strain relationship and frost resistance are experimentally studied and theoretically analyzed.The main research work is as follows:(1)It can be considered to study the influence of single-factor steel slag coarse aggregate and steel slag fine aggregate on the working performance and strength of concrete.The results show that the performance is better when the content of steel slag coarse aggregate and steel slag fine aggregate content range from 20% to 60%.The results of the three-factor three-level orthogonal test show that the cubic compressive strength and split tensile strength are optimal when the steel slag sand content is 20%,the steel slag stone content is 20%,and the sand ratio is 0.38.(2)Research on the stress-strain constitutive relationship of steel slag aggregate concrete under uniaxial compression.The research results show that the failure modes of steel slag aggregate concrete and ordinary concrete under uniaxial compression are both oblique shear failure.Overall curve,normal concrete is fuller.Steel slag aggregate concrete becomes taller and thinner with the increase of aggregate content.Research on the characteristic values of the stress-strain curve found that the elastic modulus of steel slag aggregate concrete is higher than that of ordinary concrete.Increase in content,increase elastic modulus.The incorporation of steel slag aggregate increases the peak strain,which improves the deformation performance of concrete to a certain extent.It can be discussed the fitting curve of the Zhenhai model and the stress-strain curve of steel slag aggregate concrete.The fitting accuracy is above 0.9,and the fitting effect is good.(3)The uniaxial compressive strength of steel slag aggregate concrete is higher than that of ordinary concrete.It can be considered that to observe the transition zone between steel slag aggregate concrete and ordinary concrete,hydration products by scanning electron microscope.The hydration products of both contain coral-like C-S-H gel.There are micro-cracks in the transition zone between ordinary crushed stone and cement,which is extremely unfavorable to the uniaxial compression performance of concrete.The interface transition zone between steel slag aggregate and cement stone is dense,and the interface transition zone of steel slag aggregate concrete has high cohesive force and high concrete strength.(4)The research results of the frost resistance of steel slag concrete show that:Concrete with different amounts of steel slag aggregates will have a large difference in the form of failure at the same number of freeze-thaw cycles.Ordinary concrete group is the most severely damaged.With the increase of the amount of steel slag aggregate group,the lower the mass loss rate and the smaller the decrease of relative dynamic elastic modulus,the better the frost resistance of the specimen.According to the relative dynamic elastic modulus,the freeze-thaw damage model is established,and the fitting degree of the one-dimensional quadratic function is better.It can be considered about calculating the frost resistance durability life of steel slag aggregate concrete in various northern regions.The frost resistance life of the SSC20-60 group in the Northeast,Northwest,and North China regions is more than twice the life of the ordinary concrete group.It shows that steel slag aggregate can increase the durability of concrete frost resistance to a certain extent.