Analysis On Mechanical Properties And Durability Of Super-fine Sand Concrete Of Liao River

Liao River has rich resources of superfine sand which shows a borad prospect of application. But the workability, compressive strength and durability of super-fine sand concrete are poorer than those of well graded concrete. In this study, selecting the superfine sand of Liao River as the research object, firstly,concrete of the sand has been compounded with different mix proportion. Then the scanning electron microscope has been used to observe the microstructure of the concrete with such proportion and the compressive strength and durability tests have been carried out so as to find out the influence of different water cement ratio on its microstructure, compressive strength, durability and the relationship between such parameters. The results of this study can be utilized to provide theoretical basis for scientific application of the superfine sand in the future. The main research achievements are as follows:(1)Results of the compressive strength test show that the strength of the superfine sand concrete decreases while the water cement ratio increases,The compressive strength reaches the top point when the water cement ratio is 0.45, and it reaches the bottom when the ratio is 0.55.Using the SPSS software to make the regression analysis, the formula for computing compressive strength of the superfine sand concrete have been obtained which is fcu,o＝0.34×fce× (C/W＋0.35).(2)Through analyzing the results of the scanning electron microscopy,it is observed that, the microstructure of superfine sand concrete has an impact on its compressive strength. The strength is high when the pores and cracks in the microstructure of the concrete are small and dense—and vice versa..Therefore, the compressive strength can be increased by improving the microstructure and the density of superfine sand concrete.(3)After analyzing the result of the durability tests, it is found that when the water-cement ratio is 0.45, the sand rate is 27% and water reducer is 1.2% of the amount of cement, the samples of superfine sand concrete can withstand the maximum times of freeze-thaw cycle(215), of which the frost resistance grade reaches F200 and anti-permeability level reaches W6.