关键词: 花岗岩石粉;超高性能混凝土;力学性能;微观结构

Abstract: The effects of granite powder substituted quartz powder on the mechanical properties (3 d,180 d compressive and flexural strength) and microstructure (hydration product,C-S-H gel average molecular chain length) of ultra high performance concrete under autoclaved curing conditions were studied.And the relationship between them were verified.The results of XRD,SEM-EDS and 29Si NMR show that the hydration products of 3 d and 180 d are mainly tobermorite crystals with low calcium silicon ratio and high intrinsic strength.With the increasing of the substitution rate of granite powder,the compressive and flexural strength of concrete increase first and then decrease.When the substitution rate is 50％,the compressive strength is over 190 MPa and tne flexural strength is over 40 MPa under the ages of 180 d.And the average molecular chain length of C-S-H gel decrease,Al[4]/Si increase with the increasing of the substitution rate.The average molecular chain length is 180 d ＞3 d,and Al[4]/Si is 180 d ＜3 d at the same substitution rate.Under high temperature and high pressure conditions,the average molecular chain length of C-S-H gel is not a single factor of concrete performance.The compressive strength of concrete is not directly related to the average molecular chain length of C-S-H gel.

Key words: granite powder;ultra high performance concrete;mechanical property;microstructure