To reveal the influence of mechanical activation on the performance of fly ash, the microanalysis（the energy spectroscopy, XRD and SEM）, the distribution size of particle of fly ash and cement paste intensity of var...To reveal the influence of mechanical activation on the performance of fly ash, the microanalysis（the energy spectroscopy, XRD and SEM）, the distribution size of particle of fly ash and cement paste intensity of various age for different grinding time were studied. The relationships of the activity and the composition of fly ash, microstructure and the distribution of particle size by mechanical activation of fly ash were obtained. The internal glass beads with activity were released by grinding fly ash for a certain time. The particle specific surface area was improved and the hydration reaction of the interface and the surface active center was increased by grinding. The granularity distributing of fly-ash trended towards optimization. The polar molecules or ions were easier to intrude into the internal cavity of the vitreous body. The active silica and alumina of fly ash were rapidly depolymerized. Each performance index of fly ash was increased before grinding for 20 min. Cement paste intensity of various age increased along with the grinding time, and the early strength increase range was big, but the later period intensity increase range hastened slightly. The internal part of vitreous of fly ash was destroyed if the fly ash continued to be ground and the activity of fly ash was reduced. It is suggested that Guozhuang＇s fly ash should be ground for 20 min.展开更多
To obtain the compositions and microstructure of hydration products of cementitious material in different hydration ages and its growth law of filling strength, the optimal proportion of composite cementitious materia...To obtain the compositions and microstructure of hydration products of cementitious material in different hydration ages and its growth law of filling strength, the optimal proportion of composite cementitious material was determined according to the chemical composition of cement clinker which was composed of the Portland cement 32.5R, CSA 42.5 sulphoaluminate cement and two gypsum（CS）. The characterization of composite cementitious materials in different hydration ages was conducted by NMR, XRD and SEM techniques. The mechanism of hydration was explored. It is shown that the compressive strength of the test block increases gradually with the increase of hydration age. The microstructure of composite cementitious material can be changed from Al-O octahedron into Al-O tetrahedron in the hydration process. The hydrated alkali alumi niumsilicate formed with Si-O tetrahedron and Al-O tetrahedron. The degree of polymerization of Si-O tetrahedron gradually increased, and the structural strength of cementitious materials continued to increase. The diffraction peak of clinker minerals gradually decreased with the extension of hydration age. The CaSO4 completely hydrated to produce Aft during hydration which resulted in high early strength of cementitious material. The early hydration product of composite cementitious materials was Aft with a needle bar structure. The main middle and last hydration products were CSH gel and CH gel with dense prismatic shape. The microscopic pore of composite cementitious material gradually decreased and improved the later strength of filling block. The strong support was provided for mined-out area.展开更多
基金Funded by the National Natural Science Foundation of China(No.51574055)
文摘To reveal the influence of mechanical activation on the performance of fly ash, the microanalysis（the energy spectroscopy, XRD and SEM）, the distribution size of particle of fly ash and cement paste intensity of various age for different grinding time were studied. The relationships of the activity and the composition of fly ash, microstructure and the distribution of particle size by mechanical activation of fly ash were obtained. The internal glass beads with activity were released by grinding fly ash for a certain time. The particle specific surface area was improved and the hydration reaction of the interface and the surface active center was increased by grinding. The granularity distributing of fly-ash trended towards optimization. The polar molecules or ions were easier to intrude into the internal cavity of the vitreous body. The active silica and alumina of fly ash were rapidly depolymerized. Each performance index of fly ash was increased before grinding for 20 min. Cement paste intensity of various age increased along with the grinding time, and the early strength increase range was big, but the later period intensity increase range hastened slightly. The internal part of vitreous of fly ash was destroyed if the fly ash continued to be ground and the activity of fly ash was reduced. It is suggested that Guozhuang＇s fly ash should be ground for 20 min.
基金Funded by the National Natural Science Foundation of China(No.51574055)the Natural Science Foundation of Liaoning Province(No.20170540143)
文摘To obtain the compositions and microstructure of hydration products of cementitious material in different hydration ages and its growth law of filling strength, the optimal proportion of composite cementitious material was determined according to the chemical composition of cement clinker which was composed of the Portland cement 32.5R, CSA 42.5 sulphoaluminate cement and two gypsum（CS）. The characterization of composite cementitious materials in different hydration ages was conducted by NMR, XRD and SEM techniques. The mechanism of hydration was explored. It is shown that the compressive strength of the test block increases gradually with the increase of hydration age. The microstructure of composite cementitious material can be changed from Al-O octahedron into Al-O tetrahedron in the hydration process. The hydrated alkali alumi niumsilicate formed with Si-O tetrahedron and Al-O tetrahedron. The degree of polymerization of Si-O tetrahedron gradually increased, and the structural strength of cementitious materials continued to increase. The diffraction peak of clinker minerals gradually decreased with the extension of hydration age. The CaSO4 completely hydrated to produce Aft during hydration which resulted in high early strength of cementitious material. The early hydration product of composite cementitious materials was Aft with a needle bar structure. The main middle and last hydration products were CSH gel and CH gel with dense prismatic shape. The microscopic pore of composite cementitious material gradually decreased and improved the later strength of filling block. The strong support was provided for mined-out area.
