Study On The Performance Of High Performance Concrete With Polycarboxylate Superplasticizer And Machine-made Sand In Guangxi

As an indispensable and important part of concrete structure,fine aggregate is widely used in infrastructure construction.With the continuous enhancement of environmental protection awareness and the decrease of natural sand resources year by year,it will become an inevitable trend to replace natural sand with machine-made sand.There are significant differences in the particle morphology,the particle grading and other performance parameters of machine-made sand in different regions,which has a greater impact on the performance of concrete.Therefore,it has extremely important practical value and theoretical significance to carry out research on the performance parameters of machine-made sand and the mix ratio of machine-made sand high-performance concrete in different regions.In this paper,sixteen kinds of machine-made sands from five regions of Guangxi are selected,and their performance parameters such as stone powder content,apparent density,crush value and MB value are determined according to the requirements of the specification,and the performance parameters of machine-made sands from different divisions in Guangxi and sixteen kinds of Guangxi areas are obtained.The representative value of machine-made sand performance parameters.The statistical significance test method and Pearson coefficient are used to analyze the correlation between the performance parameters of the machine-made sand,and the correlation degree and significance level between the different parameters are obtained;a digital camera and a Leica microscope are used to compare the 13 Image analysis is carried out on the shape of different particle sizes of Guangxi machine-made sand,and the aspect ratio and roundness coefficient of different particle sizes are obtained,and the angularity and fluidity are measured by this;Zeiss scanning electron microscope,laser particle size analyzer,X-ray The large-scale precision instrument of diffractometer and fluorescence spectrometer conducts microscopic analysis on machine-made sand particles of0.15mm～0.075mm and stone powder below 75μm,and obtains the microscopic characteristics of machine-made sand in Guangxi,such as the particle size distribution width and mineral and chemical composition.In this paper,the Marsh cylinder method and the pure slurry fluidity method are used to determine the compatibility between powder and liquid polycarboxylic acid superplasticizers and cement.The test shows that the powder polycarboxylic acid superplasticizer is the most suitable Type of water reducing agent,0.8～1%is the best content;according to Boromi’s formula and design points of high performance concrete mix ratio,the water-binder ratio is selected as 0.32 and 0.35,the sand ratio is 0.4 and 0.42,and the unit water consumption It is 170kg/m~3,the blending amount of polycarboxylic acid water reducing agent is 1%,and the preliminary mixing ratio is selected through performance test.Taking the machine-made sand concrete in Guangxi as the experimental group and the machine-made sand concrete in southwest region as the control group,the high performance of machine-made sand was optimized by comparing the workability,compressive strength,anti-carbonization and anti-chloride ion permeability of the two types of machine-made sand high-performance concrete.The key parameters of concrete,such as water-binder ratio and sand ratio,are finally put forward to meet the characteristics of machine-made sand in Guangxi.The key points of high-performance concrete ratio are:water-binder ratio is 0.3,sand ratio is 0.44,unit water consumption is175 kg/m~3,the content of polycarboxylic acid water reducing agent is 0.8%.