Study On The Influence Of The Admixture Of Granite Powder On The Performance And Microstructure Of Hydraulic Concrete

With the advance of eco-civilization city construction,the state's requirements for the green,high-efficiency,energy-saving,environmental protection and sustainable development of the stone industry are constantly increasing.At present,the overall stone industry keeps a good momentum,but the waste of stone powder resources and environmental pollution occur from time to time.In recent years,the state's investment in water conservancy infrastructure construction has increased year by year,and the application scale of hydraulic concrete has become larger and larger.The research and development of green and high-performance hydraulic concrete materials with excellent performance by adding an appropriate amount of mineral admixtures has become a hot topic.The previous research of the research group found that adding appropriate amount of granite powder when preparing concrete materials can improve its service performance,solve the problems of environmental pollution and the use of waste resources,and realize the sustainable development of social eco-civilization.In this paper,combined with the previous experimental research by the research group and taking the hydraulic concrete?G-??G-??G-??with different amount of admixture of0⁴5?m?G_I?,0⁸0?m(G_II),and 0¹50?m(G_III)granite powder as the research objects.The effects of fineness and content of granite powder on the performance of hydraulic concrete were explored through mechanical property tests and durability performance tests to find out the fineness and external content of granite powder that effectively improve the performance of hydraulic concrete.Combined with microscopic experiments,the influence of adding granite powder on the microstructure of hydraulic concrete was analyzed,and the mechanism of its influence on various properties of hydraulic concrete was revealed from the microstructure level,and the conclusion of macroscopic performance test was verified.The conclusions are as follows:?1?Adding appropriate amount of granite powder can effectively improve the mechanical properties of hydraulic concrete.With the increase of the content of granite powder,the strength increases first and then decreases.When 20%G_I,20%G_III or 22.5%G_IIIII are added,the strength of each group of hydraulic concrete is the highest,and G_22.5-?(the content of G_IIIII is 22.5%)is the best.The 28d compressive strength is 61.34MPa and the flexural strength is9.02MPa,which increased by 29.77%and 21.24%respectively compared with the base group C0.?2?With the increase of the admixture of granite powder added with different fineness,the durability of hydraulic concrete shows a trend of strengthening first and then weakening.When the amount is less than 15%,the durability performance is G-?,G-?,G-?,from strong to weak,and G-?,G-?,G-?when it exceeds 20%.Through comprehensive analysis,it is determined that the impermeability,frost resistance and carbonation resistance of hydraulic concrete are the best at G_17.5-?,G₂₀-?and G_22.5-?respectively.Compared with C0,the relative permeability coefficients of each group of hydraulic concrete are reduced by 56.48%,57.04%,58.70%,the frost resistance level is increased to above F350,and the carbonation depth at 28d is reduced by 17.24%,20.95%,23.87%;the resistance to chloride ion erosion is the best when each group is G_17.5-?,G_17.5-?,and G₂₀-?,compared with C0,the diffusion coefficient of chloride ion decreases by 18.61%,19.80%,20.97%.The durability of hydraulic concrete is improves significantly.?3?Taking into account the different fineness and different admixtures of granite powder to improve the mechanical and durability performance of hydraulic concrete,according to the available granite stone particle grading,it is recommend to add 17.5²0%G_I or 17.5²0%G_III or 20²2.5%G_III.Among them,the addition of G_IIIII has the best effect in improving the performance of hydraulic concrete,and the utilization efficiency of granite powder is the highest.?4?Adding appropriate amount of granite powder with different fineness,the pore structure parameters of hydraulic concrete are optimized,the proportion of harmful pores is reduced,the complexity of pore spatial distribution is increased,the density is improved,the structure is better.Therefore,the ability of hydraulic concrete to resist the invasion of harmful substances is enhanced.Through fitting,it is found that the size of contribution porosity of harmful pores can better reflect the performance of hydraulic concrete.The analysis of the phase composition shows that the addition of granite powder accelerates the hydration process of minerals such as C₂S and C₃S;it exerts a weak volcanic ash effect,consumes part of Ca?OH?₂,and increases the production of CaSiO₃,Ca₃Si₂O₇ and other products,which was beneficial to the performance of hydraulic concrete.Through the observation of SEM images,it can be seen that granite powder exerts a good micro-aggregate filling effect and micro-crystalline core effect,which improves the integrity and compactness of the hydraulic concrete microstructure,the optimal mix proportion is G_22.5-III.However,when the content is too much,the microstructure of hydraulic concrete deteriorates and its performance decreases.The micro-test results correspond to the macro-performance conclusions,revealing the action mechanism of the added granite powder in the concrete.The research results of this paper have certain reference value and theoretical guiding significance in the design,promotion and application of admixture hydraulic concrete.