Research Of High Performance Concrete Prepared With The Steel Industry Solid Waste As Raw Materials

Iron and steel industry is the important basic industry of national economy in our country.With the development of iron and steel industry and the improvement of productivity level,resources,energy consumption and waste emissions problem are increasingly serious.Steel slag(SS)and blast furnace slag(BFS)is the most representative in the steel industry solid wastes.High-performance concrete(HPC)is prepared with solid waste from iron and steel industry,which can effectively solve the difficult use of iron and steel industry solid waste.Cementitious materials is prepared with SS,BFS and desulfurization gypsum(DG).And HPC is prepared with waste rock and iron tailings as the coarse and fine aggregate.The Synergistic hydration reaction mechanism of the cementitious materials is fundamental researched.Ultrafine grinding of SS makes change of the crystal structure and increases the specific surface area,which can play a Mechanical force role activation.The more suitable specific surface area is 560m2/kg.The particle size distribution of SS has fractal characteristics and present a linear correlation with specific surface area.The comprehensive strength of cementitious materials paste will increase with appropriate dosage of CaO or Na2SO4 as the excitation agent in the early ages,which will have little influence on the later comprehensive strength and hydration reaction products.The process of hydration reaction of cementitious materials is simulated according to the Krstulovic-Dabic hydration kinetics model.The results show that,with the increasing of SS content,the hydration heat of each stage decreased.The hydration process of cementitious materials containing different content of SS can involve three stages,nucleation and crystal growth(NG),interactions at phase boundaries(Ⅰ)and diffusion(D).With the dosage of SS increasing,the hydration reaction induction period prolonged and the generation of hydration products will slow.NG dominates in the early stage of hydration.I becomes the dominating factor gradually as the hydration degree increases.And D dominates in the last stage of hydration.With the increasing of SS content from 10%to 40%in cementitious materials,the comprehensive strength of concrete shows lower first and increase later.When the SS content,BFS content and DG content are 40%,48%and 12%respectively,the specific surface area of SS,BFS and DG are 560m2/kg,580m2/kg and 640 m2/kg respectively,the dosage of cementitious material is 500kg/m3,water/cement ratio is 0.27,PC exciting agent content is 0.4%of cementitious material and the sand rate is 0.37,curing temperature is 30 ℃,the compressive strength of HPC can reach 71.47MPa at 28 days cured age.The HPC has good durability performance,which accords with the national standard of ordinary concrete long-term performance and durability performance test method standard of technical requirements(GB/50082-2009).The hydration products of slag-slag-desulphurization gypsum cementitious materials at all ages mainly include ettringite(AFt),Ca(OH)2,C2S,C3S and RO phases.The synergistic hydration reaction of SS and BFS promotes the formation of hydration products.The SS and BFS can promote the hydration of each other under the effect of DG and the major hydration products are ettringite(AFt)and calcium silicate hydrate(C-S-H)gels.Hydration products quantity increased rapidly,which is similar to C-S-H amorphous gel and class zeolite facies.AFt crystal,which are similar to the needle,insert into C-S-H gel and made the structure of hardened paste more densify.