水化硅酸钙层间水吸附规律及其对分子结构的影响

Adsorption Law of Interlayer Water of Calcium Silicate Hydrate and Its Effect on the Molecular Structure

水化硅酸钙(C-S-H)是水泥水化产物中的主要组成成分,而层间水对C-S-H的物理化学性能有重要影响。利用分子动力学模拟C-S-H对水分子的吸附,得到280~320 K区间多个温度的C-S-H对水分子的吸附等温线。结果表明,不同温度条件下,C-S-H对水分子的最大吸附量变化不明显,而对水分子的吸附能力随温度升高而降低;提出了温度为280~320 K时,C-S-H对水分子的的吸附式。不同层间水覆盖率的C-S-H晶胞的结构特征表明,随着层间含水量的增大,C-S-H结构分层更加明显。达到不同层间水覆盖率时,吸附水在层间的位置不同导致C-S-H体积增大率不同。吸附水使C-S-H体积增大,密度减小,但C-S-H中原有的原子结构更加紧密。

Calcium silicate hydrate(C-S-H)is the main component of cement hydration products,and interlayer water has a significant impact on the physicochemical properties of C-S-H.Molecular dynamics method was employed to simulate the adsorption process of water molecules by C-S-H,and the adsorption isotherms of C-S-H on water molecules with multiple temperatures in the range of 280—320 K were obtained,and it could be found that the maximum adsorption amount of each temperature did not change much,but the adsorption capacity of C-S-H for water molecules decreased with increasing temperature.Furthermore,an adsorption equation at the temperature of 280—320 K was proposed.The structural characteristics of the C-S-H unit cell with different water coverage ratios between layers showed that the C-S-H structure stratification was more obvious as the interlayer water content increased.When the different coverage ratios of interlayer water were reached,the positions of the adsorbed water were different,resulting in a different volume increase rate of C-S-H.The volume of C-S-H increased due to the adsorption of water,and the density decreased,but the original atomic structure in C-S-H were more compact.