关键词: 无机纳米矿粉;水泥复合净浆;化学收缩;自收缩

Abstract: Based on ASTM standards and modified test method ,the chemical and autogenous shrinkages of cement composite paste were measured to investigate the influences of single addition of one of three inorganic nano-powder , such as amorphous nano-SiO2 with different particle sizes , hydrophilic or surface prewetted nano-CaCO3 , or nano-TiO2 with various crystal forms and particle sizes on the early-age shrinkage of paste .Results show that within a certain mass proportion , the addition of inorganic nano-powder obviously increases both chemical and autogenous shrinkages of composite paste , and with time passing,the increments become more evident .The addition of nano-SiO2 exerts the most effect, especially using the smaller nano-particle.Compared to the hydrophilic or surface prewetted nano-CaCO3 , the hydrophilic one leads to higher early-age shrinkage of paste under the condition of the same mass proportion.With 3.0%-5.0%of nano-TiO2 admixed, though the highest chemical shrinkage of paste is observed , there is no remarked growth for autogenous shrinkage , much less than that added with nano-SiO2 or nano-CaCO3 .It can be concluded that the influence of inorganic nano-powder on the early-age shrinkage behavior of composite paste depends on the type , crystal form, particle size, surface status and mass proportion of the added inorganic nano-powder .

Key words: inorganic nano-powder;cement-based composite paste;chemical shrinkage;autogenous shrinkage