title: Microstructural changes of globules in calcium-silicate-hydrate gels with and without additives determined by small-angle neutron and X-ray scattering.
abstract: The microstructure of calcium-silicate-hydrate (C-S-H) gel, a major hydrated phase of Ordinary Portland Cement, with and without polycarboxylic ether (PCE) additives is investigated by combined analyses of small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) data. The results show that these comb-shaped polymers tend to increase the size of the disk-like globules but have little influence on the thickness of the water and calcium silicate layers within the globules. As a result, the fractal packing of the globules becomes more open in the range of a few hundred nanometers, in the sense that the mass fractal dimension diminishes, since the PCE adsorption on the globules increases the repulsive force between and polydispersity of the C-S-H units. Moreover, scanning electron microscope (SEM) study of the synthesized C-S-H gels in the micrometer range shows that the PCEs depress the formation of fibrils while enhancing the foil-like morphology.
authors.affiliation: Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA. weishanc@mit.edu
authors.forename: Wei-Shan
authors.initials: WS
authors.lastname: Chiang
authors.forename: Emiliano
authors.initials: E
authors.lastname: Fratini
authors.forename: Francesca
authors.initials: F
authors.lastname: Ridi
authors.forename: Sung-Hwan
authors.initials: SH
authors.lastname: Lim
authors.forename: Yi-Qi
authors.initials: YQ
authors.lastname: Yeh
authors.forename: Piero
authors.initials: P
authors.lastname: Baglioni
authors.forename: Sung-Min
authors.initials: SM
authors.lastname: Choi
authors.forename: U-Ser
authors.initials: US
authors.lastname: Jeng
authors.forename: Sow-Hsin
authors.initials: SH
authors.lastname: Chen