Study On The Preparation Technology And Mechanical Properties Of High-performance Concrete

High-performance concrete（HPC）is a new generation of cement-based building materials with high mechanical properties,good working performance and high volume stability to meet different construction needs of engineering applications.When making high-performance concrete,the strength and toughness of HPC are usually improved by mixing mineral doping and high strength steel fibers,but in order to design concrete with better performance,it is necessary to study the influence of mineral doping material,steel fiber and so on the performance of high-performance concrete.The purpose of this study is to study HPC’s coordination ratio,microstructure,mechanical performance and strength prediction model,fiber-base interface performance,in order to obtain low-cost,high-strength,high-tough HPC.First of all,the design of HPC matching ratio is carried out,and the influence of different matching ratios over HPC’s aesthetic properties,hydration products,microstructures,hole structures and hydration processes is studied,and the optimal match ratio of HPC is selected.Then,the effect of fiber shape and orientation on the transition zone performance of fiber and substate interface in HPC was studied.Finally,on the basis of the study of HPC mechanical performance,an HPC strength prediction model is established.The main conclusions are as follows:（1）With the gradual increase of fiber doping,the pres sure-resistant strength and folding strength of HPC of different long diameters show a trend of rising and then decreasing.The pressure strength and fold strength reached the maximum value of 88.69MPa and 7.01MPa respectively when the fiber was doped by 3%,which increased by 8.09%and 31.77%respectively compared with the concrete.The pressure-resistant strength and folding strength of the mixed fibers reached 86.75MPa and 6.95MPa respectively when the fiber was doped at 2%,respectively,which increased by 5.73%and 30.64%compared with the concrete.（2）Adding 10% powdered ash and 10% silicon ash can improve HPC’s working performance,and adding nanomaterials can reduce HPC’s working performance.The hydration reaction was accelerated by the coal ash,silicon ash and nano-silicon dioxide,and the hydration heat was reduced.Mixing nano-silicon dioxide and silicon ash can significantly reduce the porosity of concrete.（3）The effect of fiber shape on the performance of fiber-base interface is that the hook fiber is better than the corrugated fiber is better than the straight fiber.The pull-out load is greatly affected by the fiber orientation,and the pull-out load of the fiber at 30 and 45 degrees is larger than the pull-out load of the fiber at 0 and 60 degrees.With the increase of the substitution volume fraction of Copper coated fiber,the average interface bonding strength and interface of straight fiber showed a linear increase,while the opposite trend was shown for corrugated fiber and hook fiber.The type of steel fiber does not have a great effect on the stretch stiffness of HPC as a whole.After the cement substation is cracked,the type of steel fiber plays a decisive role in stretching stiffness,and the stretching performance of the corrugated fiber is better than that of the hook fiber.（4）When the fiber doping is 0.5% to 2%,the predicted value of the pressure strength and the anti-fold strength have a small error with the measured value,the fitting degree is better,and when the fiber doping is too large,the fit degree is poor.The HPC anti-pressure strength prediction model is f_cuf=f_cu+0.014f_cuRI_V+1.09RI_V,and the HPC anti-fold strength prediction model is f_lf=6.4+3.43V_f+0.32V_f².