中文摘要：

利用压汞、纳米压痕以及27Al固体核磁共振方法,系统研究了不同碱金属离子（Na^＋和K^＋）与含量对水泥基材料早期自收缩和干燥收缩性能的影响规律。结果表明,超量的Na^＋或K^＋均促进了水泥基材料早期自收缩和干燥收缩,但K^＋的促进作用明显大于Na^＋,其机制在于：（1）K^＋比Na^＋更易促进水泥基材料中小于50纳米孔数量的增加,这使得超量K^＋水泥基材料在干燥时具有更大的收缩驱动力;（2）虽然K^＋比Na^＋更易促进水泥基材料生成高密度水化硅酸钙（HD C-S-H）,但同时超量K^＋水泥基材料中C-S-H总量也较高,大量的C-S-H是导致较高早期收缩的根源;（3）与Na^＋相比,K^＋更明显地阻碍了钙矾石（AFt）晶体的形成,削弱了AFt的骨架作用,且K^＋可促使AFt向单硫型水化硫铝酸钙（AFm）转变,因而导致超量K^＋水泥基材料更易发生收缩变形。

英文摘要：

The influence of the different metal ions（K^＋and Na^＋） and alkali content on autogenous shrink-age and drying shrinkage at early age has been investigated through mercury intrusion porosimetry（MIP）,nanoindentation and27 Al magic angle spinning nuclear magnetic resonance（27Al MAS NMR）. The results in-dicate that the autogeneous and drying shrinkage of cement-based materials are increased by K^＋or Na^＋,whereas the effect of K^＋is much more obvious. The mechanisms of these phenomena are attributed to threereasons：（1） the capillary pores less than 50 nm in cement-based material with high K^＋content are morethan those with high content Na^＋, leading to a higher driving force when shrinkage occurs;（2） K^＋tendsto promote the formation of high density calcium silicate hydrate（HD C-S-H）, but the total content ofC-S-H in cement-based material with high K^＋content is higher than the one with high Na^＋content, andthe large amount of C-S-H is primary cause of high early-age shrinkage; and（3） K^＋is easier to hinderthe formation of AFt and accelerate the transformation of AFt to AFm than Na^＋at early age, leading tothe weak framework function of AFt. The cement-based material with high K^＋content has more shrinkagevalues at early-age.