Study on mechanical properties and water absorption characteristics of fly ash concrete modified by nano-SiO2
In order to explore the high performance of fly ash concrete,the mechanical and water absorption tests of nano-SiO2 modified fly ash concrete were carried out.The effects of replacement rate of fly ash and nano-SiO2 content on the mechanical properties(compressive strength,splitting tensile strength and dynamic elastic modulus)and water absorption characteristics of concrete were studied.The results show that the mechanical properties of fly ash concrete increase first and then decrease with the increase of nano-SiO2 content.When the nano-SiO2 content increases from 0%to 2%,the 28 d compressive strength,splitting tensile strength and dynamic elasticity modulus of fly ash concrete increase by 12.90%,7.53%and 5.85%,respectively.Therefore,nano-SiO2 has a more significant impact on the compressive strength.When the replacement rate of fly ash increases from 10%to 30%,the 28 d compressive strength,splitting tensile strength and dynamic elastic modulus of concrete decrease by 7.24%,2.61%and 9.87%,respectively,so the influence of fly ash on the dynamic elastic modulus is more significant.With the increase of nano-SiO2 content,the capillary water absorption coefficient of fly ash concrete shows a trend of first decreasing and then increasing.The capillary water absorption coefficient of concrete increases with the increase of replacement rate of fly ash.The higher the replacement rate of fly ash,the more significant the influence of nano-SiO2 on the capillary water absorption coefficient of concrete.The replacement rate of fly ash and the content of nano-SiO2 have no significant influence on the correlation between the mechanical properties of concrete and the capillary water absorption coefficient.The compressive strength,splitting tensile strength,and dynamic elastic modulus of concrete have negative correlation with the capillary water absorption coefficient,and the compressive strength has the best correlation with the capillary water absorption coefficient.
fly ash concretenano-SiO2mechanical propertywater absorption characteristiccapillary water absorption coefficient
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