共查询到18条相似文献,搜索用时 64 毫秒
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熟料中SO3含量对低热水泥性能的影响及机理研究 总被引:1,自引:0,他引:1
检测了同一温度下烧制的不同SO3含量的熟料制成的低热水泥的物理性能及水化速率,并采用岩相分析、XRD、EDS、化学分析方法研究了熟料中SO3含量对低热水泥熟料岩相结构、矿物组成、矿物晶型及矿物固溶组分的影响.结果表明,随着熟料中SO3含量的增加,水泥凝结时间显著延长,水化速率提高,7d、28d强度和水化热增大;提高熟料中SO3含量有利于A、B矿的生长和发育;熟料中SO3含量越高,早强矿物C4A3S的峰强越高,高温型B矿特征峰变窄而峰强变高,结晶程度提高;熟料中的SO3大部分固溶在硅酸盐矿物中,尤其是B矿中,SO3的引入,使A、B矿的Ca/Si增大,铝铁固溶量增多,其固溶异离子的量越多,越有利于活化阿利特晶体,稳定及活化贝利特的高温晶型,从而提高水泥的水化活性,增大水泥的后期强度. 相似文献
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低热硅酸盐水泥具有高温下强度稳定增长的特性,本文以硅酸盐水泥和低热硅酸盐水泥互为对比,研究了在水泥砂浆成型之后直接进行热养护(50~80℃)和标准养护1 d后再进行热养护两种情况下的强度发展和水泥浆体的物相组成、孔隙发展、微观形貌特征。结果表明:高温条件下水泥强度损伤行为源于水化后期的微结构劣化,但这一行为与水化初期受热密切相关,低热硅酸盐水泥在高温下较低的水化速率使其水化产物更均匀、密实,浆体的孔结构不随温度的升高以及受热方式的改变出现明显劣化,因此其强度在高温下仍能保持稳定增长;硅酸盐水泥后期由高温引发的钙矾石分解并没有直接导致强度倒缩,但水化初期过高的水化速率使水泥浆体出现更多的孔洞和缺陷,加速了后期由高温引起的单硫型水化硫铝酸钙(AFm)、Ca(OH)2析出与生长,且诱发浆体孔隙率增大。 相似文献
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不同烧成温度下形成的硫铝酸盐水泥熟料及其性能研究 总被引:4,自引:0,他引:4
1引言近年来,我国对以C4A3S为基础的特种水泥的研究和生产有了很大的进展[1,2],这种水泥主要由C4A3S、C2S和石膏等矿物组成,具有早强、高强、高抗渗、高抗冻、耐腐蚀和低碱性等特点,越来越受到土木工程界的重视,先后成功地用于建筑工程、水泥制品... 相似文献
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低热硅酸盐水泥因水化热低而被大量应用于高等级大体积混凝土工程以降低温度应力给结构带来的开裂风险。此外,高温下强度增长稳定的特点决定其能在高热施工环境发挥作用,优良的体积稳定性有利于解决混凝土结构开裂问题,较高的后期强度和优良的抗侵蚀性能适合用于高性能混凝土的制备。本文从水化、性能等角度出发,分析了低热硅酸盐水泥在水化调控、水化产物及微观结构、性能优化等方面存在的部分问题,总结了低热硅酸盐水泥高温耐受、抗侵蚀、体积稳定等性能特点,提出了低热硅酸盐水泥在严酷环境、高热环境中的应用展望。 相似文献
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以铝酸盐水泥熟料、硅酸盐水泥熟料和粉煤灰为原料,探讨了掺加少量铝酸盐水泥熟料对硅酸盐水泥及粉煤灰硅酸盐水泥复合体系水化、凝结和硬化性能的影响。结果表明,在硅酸盐水泥及粉煤灰硅酸盐水泥中掺加铝酸盐水泥熟料,可以明显缩短水泥的初、终凝时间,但复合体系的需水量增加;掺加少量铝酸盐水泥熟料(≤3%)可明显提高硅酸盐水泥的早期强度,但后期强度(28d)有所降低;当铝酸盐水泥熟料的掺量达5%时,水泥的各龄期强度均明显降低。少量铝酸盐水泥熟料掺加到粉煤灰硅酸盐水泥中,复合体系的各龄期强度都明显提高,且早期强度的提高幅度较大。 相似文献
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阿利特—硫铝酸盐水泥与硅酸盐水泥复合性能的研究 总被引:10,自引:1,他引:10
研究了阿利特-硫铝酸盐水泥与硅酸盐水泥复合所制备的水泥的性能。结果表明,复合后水泥的强度性能优于单一品种水泥的性能;凝结时间则由复合体中占比例较多的一种水泥所控制。 相似文献
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A new method of burning Portland cement clinker is studied. The microwave sintering is adopted after the raw meal is heated to certain temperature in an electric furnace. The experimental results show that after the raw meal is heated at a low electric heating temperature (1000-1200 °C) and then further sintered with microwave for 1 to 2 min, Portland cement clinkers can be formed. The f-CaO contents of the clinkers are 1-2%. It has also been found that the higher the temperature of the samples put into the microwave cavity, the shorter the time needed for microwave burning. When the temperature is up to 1300 °C, the sample needs to be heated by microwave for only 40 s, and the f-CaO content decreases to 0.65%. It has been proved by the experiments that (1) the new burning technique can greatly increase the forming speed of Portland cement clinkers, (2) Fe2O3 can enhance the microwave clinkering. XRD patterns of the clinkers show that their mineral compositions and the characteristic XRD peaks are similar to those of clinkers by conventional burning method. 相似文献
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When cements appeared in the 19th century, they took the place of traditional binding materials (lime, gypsum, and hydraulic lime) which had been used until that time. Early cements can be divided into two groups, natural and artificial (Portland) cements. Natural cements were introduced first, but their widespread usage was short-lived as they were quickly replaced by artificial cements (Portland), still the most important and predominant today. The main differences between natural and artificial cements arise during the manufacturing process. The final properties of the cements are greatly influenced by differences in the raw materials and burning temperatures employed.The aim of this paper is to assess the efficiency of traditional analytical techniques (petrographic microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR)) used to differentiate natural and artificial cements. 相似文献
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Shima Pilehvar Anna M. Szczotok Manuel Carmona Ramón Pamies Anna-Lena Kjøniksen 《Journal of the American Ceramic Society》2020,103(10):5852-5869
The effect of microencapsulated phase-change materials (MPCM) on the rheological properties of pre-set geopolymer and Portland cement mortars was examined. Microcapsules with hydrophilic and hydrophobic shells were compared. The shear rate dependency of the viscosities fitted well to a double Carreau model. The zero shear viscosities are higher for geopolymer mortar, illustrating poorer workability. The time evolution of the viscosities was explored at shear rates of 1 and 10 s−1. New empirical equations were developed to quantify the time-dependent viscosity changes. The highest shear rate disrupted the buildup of the mortar structures much more than the lower shear rate. Microcapsules with a hydrophobic shell affect the rheological properties much less than the microcapsules with a hydrophilic shell, due to the higher water adsorption onto the hydrophilic microcapsules. Shear forces was found to break down the initial structures within geopolymer mortars more easily than for Portland cement mortars, while the geopolymer reaction products are able to withstand shear forces better than Portland cement hydration products. Initially, the viscosity of geopolymer mortars increases relatively slowly during due to formation of geopolymer precursors; at longer times, there is a steeper viscosity rise caused by the development of a 3D-geopolymer network. Disruption of agglomerates causes the viscosities of portland cement mortars to decrease during the first few minutes, after which the hydration process (increasing viscosities) competes with shear-induced disruption of the structures (decreasing viscosities), resulting in a complex viscosity behavior. 相似文献