Analysis Of Cement Structure And Dynamic Of Confined Water Based On Quasi-elastic Neutron Scattering Spectra Data

Neutrons are neutral and sensitive to light elements,which are different from X-ray and used to analyze the structure and properties of hydrogen containing compounds.Quasi-elastic neutron scattering(QENS),which is different from small angle neutron scattering,diffraction and reflection,has gradually developed into an effective method to analyze the motion of atoms and molecules in compounds.Based on the jump-diffusion and rotation-diffusion model(JRM),the revised jump diffusion and rotation diffusion model(r JRM)is developed.The data of QENS spectra in this paper come from the experiments of cement samples with different additives by high resolution backscattering silicon spectrometer(BASIS)of Oak Ridge National Laboratory(ORNL).The resolution of the instrument is 3.4?e V,the neutron energy transfer ranges from–120?e V to 120?e V,and the neutron scattering vector ranges from 0.3(?)^-1 to 1.9(?)^-1.The four cement samples are:pure magnesium-silicate-hydrate(M-S-H),M-S-H with aluminum-silicate nanotubes(ASN),M-S-H with carboxyl-functionalized ASN(ASN-COOH),and pure calcium-silicate-hydrate(C-S-H).Seven parameters related to cement structure and water dynamic can be extracted by QENS spectra fitting of cement samples with r JRM model.The results show that the two additives can effectively improve the structural properties of pure M-S-H cement,and the ASN additive works better,but there is still a certain gap between the three groups of M-S-H cement and C-S-H cement.By the two-state model to analyze the diffusion of confined water,it shows that the translational dynamics of confined water of M-S-H cement has a crossover temperature near227 K,while the rotational dynamics is near 233 K.The above results show that r JRM is suitable for all the range of neutron energy transfer and scattering vector,and can obtain information about the structure and water dynamics of cement,which provides a reference for further understanding the effect of additives on pure M-S-H samples and the study of the dynamic characteristics of supercooled water.