In order to study the effect of the curing temperature on the intermediate temperature properties of calcium aluminate cement bonded corundum castables,the prepared castables were cured at 5,10,25,40 and 50℃,respecti...In order to study the effect of the curing temperature on the intermediate temperature properties of calcium aluminate cement bonded corundum castables,the prepared castables were cured at 5,10,25,40 and 50℃,respectively,dried at 110℃ for 24 h and heat treated at 800 and 1100 ℃,respectively.Then the apparent porosity,the cold modulus of rupture and the cold crushing strength were measured.The phase composition of castable matrix specimens treated under the same conditions and the influence of the curing temperature on the intermediate temperature strength of the castables were also analyzed.The results show that with the increase of the curing temperature,the hydration degree of calcium aluminate cement increases,which promotes the uniform distribution of hydration products with AI203 after decomposition,thus enhancing the intermediate temperature strength of castables.展开更多
This study aimed at assessing the usefulness of carbon microfiber (CMF) in improving the compressive-toughness of sodium metasilicate-activated calcium aluminate/Class F fly ash foamed cement at hydrothermal temperatu...This study aimed at assessing the usefulness of carbon microfiber (CMF) in improving the compressive-toughness of sodium metasilicate-activated calcium aluminate/Class F fly ash foamed cement at hydrothermal temperatures of up to 300°C. When the CMFs came in contact with a pore solution of cement, their surfaces underwent alkali-caused oxidation, leading to the formation of metal (Na, Ca, Al)-complexed carboxylate groups. The extent of this oxidation was enhanced by the temperature increase, corresponding to the incorporation of more oxidation derivatives at higher temperatures. Although micro-probe examinations did not show any defects in the fibers, the enhanced oxidation engendered shrinkage of the interlayer spacing between the C-basal planes in CMFs, and a decline in their thermal stability. On the other hand, the complexed carboxylate groups present on the surfaces of oxidized fibers played a pivotal role in improving the adherence of fibers to the cement matrix. Such fiber/cement interfacial bonds contributed significantly to the excellent bridging effect of fibers, resistance to the cracks development and propagation, and to improvement of the post-crack material ductility. Consequently, the compressive toughness of the 85°-, 200°-, and 300°C-autoclaved foamed cements reinforced with 10 wt% CMF was 2.4-, 2.9-, and 3.1-fold higher than for cement without the reinforcement.展开更多
以石灰石和工业氧化铝为原料研究了煅烧温度及配料组成对纯铝酸钙水泥性能的影响。结果表明,当 w Al2O 低于 376%时,随配料组成中 w Al2O 的增加, A 矿物的形成量增加,水泥的凝结时间延长且强度降低;...以石灰石和工业氧化铝为原料研究了煅烧温度及配料组成对纯铝酸钙水泥性能的影响。结果表明,当 w Al2O 低于 376%时,随配料组成中 w Al2O 的增加, A 矿物的形成量增加,水泥的凝结时间延长且强度降低;随煅烧温度提高,水泥的凝结 3 C 2时间延长但强度提高,尤其是 3d, 强度;掺少量 BaO , 7d ZnO 可缩短水泥的凝结时间但强度降低。展开更多
基金The authors appreciate the financial support from National Natural Science Foundation of China(No.5157244,U1604252 and 5167225).
文摘In order to study the effect of the curing temperature on the intermediate temperature properties of calcium aluminate cement bonded corundum castables,the prepared castables were cured at 5,10,25,40 and 50℃,respectively,dried at 110℃ for 24 h and heat treated at 800 and 1100 ℃,respectively.Then the apparent porosity,the cold modulus of rupture and the cold crushing strength were measured.The phase composition of castable matrix specimens treated under the same conditions and the influence of the curing temperature on the intermediate temperature strength of the castables were also analyzed.The results show that with the increase of the curing temperature,the hydration degree of calcium aluminate cement increases,which promotes the uniform distribution of hydration products with AI203 after decomposition,thus enhancing the intermediate temperature strength of castables.
文摘This study aimed at assessing the usefulness of carbon microfiber (CMF) in improving the compressive-toughness of sodium metasilicate-activated calcium aluminate/Class F fly ash foamed cement at hydrothermal temperatures of up to 300°C. When the CMFs came in contact with a pore solution of cement, their surfaces underwent alkali-caused oxidation, leading to the formation of metal (Na, Ca, Al)-complexed carboxylate groups. The extent of this oxidation was enhanced by the temperature increase, corresponding to the incorporation of more oxidation derivatives at higher temperatures. Although micro-probe examinations did not show any defects in the fibers, the enhanced oxidation engendered shrinkage of the interlayer spacing between the C-basal planes in CMFs, and a decline in their thermal stability. On the other hand, the complexed carboxylate groups present on the surfaces of oxidized fibers played a pivotal role in improving the adherence of fibers to the cement matrix. Such fiber/cement interfacial bonds contributed significantly to the excellent bridging effect of fibers, resistance to the cracks development and propagation, and to improvement of the post-crack material ductility. Consequently, the compressive toughness of the 85°-, 200°-, and 300°C-autoclaved foamed cements reinforced with 10 wt% CMF was 2.4-, 2.9-, and 3.1-fold higher than for cement without the reinforcement.
文摘以石灰石和工业氧化铝为原料研究了煅烧温度及配料组成对纯铝酸钙水泥性能的影响。结果表明,当 w Al2O 低于 376%时,随配料组成中 w Al2O 的增加, A 矿物的形成量增加,水泥的凝结时间延长且强度降低;随煅烧温度提高,水泥的凝结 3 C 2时间延长但强度提高,尤其是 3d, 强度;掺少量 BaO , 7d ZnO 可缩短水泥的凝结时间但强度降低。
