| Basalt Fiber-Reactive Powder Concrete（BF-RPC）is a new type of concrete material with good mechanical properties and durability.Compared with traditional concrete,the ratio of flexural strength to self-weight of prestressed BF-RPC beam is close to that of steel beam,which can solve the problems of high investment,poor fire resistance,and easy corrosion of steel structure under the premise of satisfying strength.economy and application prospects.At present,the research of BF-RPC mainly focuses on improving the macroscopic performance,and the research on microscopic and mesoscopic is still in the basic stage.However,the microscopic hydration products and the microscopic pore structure have an important influence on the macroscopic properties of concrete.Only by grasping the mechanism of enhancing the macroscopic properties of the microscopic and mesoscopic structures can the overall performance of BF-RPC be better improved.This paper relies on the Jilin Provincial Development and Reform Commission project "Basalt fiber activated powder composite modified concrete performance evaluation and structural design method research" to study the relationship between the micro-hydration products,meso-pores,macro-performance and multi-scale of BF-RPC.The purpose is to provide a favorable reference for the research and application of basalt fiber activated powder concrete.The specific research contents are as follows:（1）Based on the optimal mix ratio obtained in the previous research of the research group,the changes of macroscopic properties under four curing conditions of BF-RPC standard curing,50°C water bath,70°C water bath and 90°C water bath were studied.It was found that at the age of 28 days,the compressive strength of the specimens cured in a water bath at 90 °C reached a maximum value of 125.26 MPa.High temperature water bath curing has a catalytic effect on the pozzolanic reaction in BF-RPC,and the higher the curing temperature,the more obvious the catalytic effect is.On the basis of the optimal mix ratio,the influence of four single factor changes of quartz sand content,water-binder ratio,basalt fiber content and silica fume cement ratio on the macroscopic properties of BF-RPC was studied.The mechanical test of the four groups of single-factor changes found that each group achieved the maximum value at the optimal mix ratio: 112.87 MPa and flexural strength of 19.6 MPa.（2）Based on the plane stereo theory,the fluorescence enhancement method was used to increase the contrast between the pores and the matrix,and Image Pro-Plus was used to extract the pore data.The study found that water bath curing can effectively reduce the porosity,and have certain effects on the pore size distribution,abundance,convexity,fractal dimension and circularity.At the same time,the mesoporosity of BFRPC increases with the increase of the content of quartz sand and the water-binder ratio;it decreases with the increase of the content of silica fume;and among the effects of fiber content on the mesoporosity,the mesoporosity The rate appears to a minimum value at the optimal mix ratio.（3）In the study of BF-RPC micro-hydration products,based on X-ray diffraction theory,it was found that high temperature water bath curing has a catalytic effect on the pozzolanic reaction in BF-RPC,and the higher the curing temperature,the more obvious the catalytic effect.At the same time,both the water-binder ratio and the content of silica fume have a certain effect on the hydration products of BF-RPC,but the XRD diffraction patterns C2S and C3S of each group are the strongest peaks,indicating that a lower water-binder ratio is not conducive to BF-RPC.The hydration reaction is carried out.（4）Establish an inverse error propagation network（BP network）porosity prediction model,use the known mix ratio and compressive strength to predict the BFRPC mesoporosity,establish the relationship between macroscopic and mesoscopic,and test its accuracy.The maximum error of the training group is only 7.32%,and the maximum error of the test group is only 9.67%,which can reflect the relationship between the proportion of BF-RPC components,compressive strength and mesoporosity. |
