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对水泥水化生成最主要的水化产物———CSH凝胶的结构模型,特别是对90年代以来的研究报道作了综述介绍,对两种结构模型假设———单相模型和多相模型作了分析,并介绍了纳米结构模型和中介结构模型的概念。 相似文献
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C-S-H 凝胶及其研究方法 总被引:5,自引:3,他引:2
在分析C-S-H凝胶的复杂性和特征的基础上,就测定它的化学组成、C-S-H凝胶中[SiO4]4-四面体的聚合度及其结构的化学和物理的方法作了简要介绍.现代各种测试方法的出现和使用,对C-S-H凝胶的组成和集中[SiO4]4-四面体的聚合结构有了较为完整的概念. 相似文献
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以分析纯Ca(NO3)2·4H2O、Na2SiO3·9H2O、Pb(NO3)2为原料,通过溶液反应法,制备纯净的C-S-H凝胶和掺杂Pb的C-S-H凝胶,研究了C-S-H凝胶在形成过程中对Pb的吸附固化作用及掺杂Pb后C-S-H凝胶的结构变化.结果表明,可溶铅盐由2%增至6%时,C-S-H凝胶对Pb均有良好的吸附固化作用,俘获Pb总量增大.XRD图谱发现掺杂Pb的C-S-H凝胶,其主峰位置发生偏移,出现明显的Ca(OH)2衍射峰.红外测试表明含Pb C-S-H凝胶硅氧四面体的链接方式发生变化,Q2伸缩振动峰向低波数方向偏移,Q1伸缩振动峰吸收强度增加. 相似文献
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水化硅酸钙(C-S-H)凝胶是硅酸盐水泥的主要水化产物,是水泥胶凝能力的主要来源。C-S-H凝胶的纳米结构由长程无序、短程有序的类Tobermorite纳米晶组成。明确类Tobermorite相纳米晶的分子结构、氢键等分子间作用力组成及性质、H2O和羟基基团与硅氧主链的相互作用机理对理解C-S-H凝胶的胶凝能力形成机理、调控水化产物的胶凝能力具有重要意义。本文在总结固体核磁共振分析技术研究C-S-H凝胶硅氧主链结构研究进展的基础上,提出其钙硅比对硅氧主链聚合度和平均链长的影响规律,并运用固体核磁测试与第一性原理计算核磁结果相结合的研究方法,揭示了C-S-H凝胶分子结构中氢键的组成及性质,明确了水分子及羟基基团与硅氧主链的相互作用机理。 相似文献
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硅酸盐水泥混凝土的碳化分析 总被引:3,自引:2,他引:3
介绍了硅酸盐水泥混凝土的碳化反应和碳化过程,分析了Ca(OH)_2与水化硅酸钙(C-S-H)的碳化作用.Ca(OH)_2发生碳化反应的同时,C-S-H也会发生碳化反应;Ca(OH)_2的碳化产物是方解石,而C-S-H碳化后会转变成无定形硅胶,可能形成稳定性差、结晶度差的球霰石、文石,其分解温度低于方解石的分解温度;C/S低、结晶度差的C-S-H凝胶易于碳化;水泥浆体孔隙溶液中的碱含量越高,碳化速度越快,深度越大. 相似文献
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水化硅酸钙纳米结构研究进展 总被引:6,自引:0,他引:6
介绍了水化硅酸钙凝胶(C-S-H)的几种主要结构模型,重点阐述了纳米尺度的凝胶模型及其发展。在纳米凝胶模型中C-S-H是由最小结构单元近似为直径小于5nm的胶束堆积而成。根据胶束堆积密度的差异,C-S-H分为高密度和低密度2种不同的凝胶相。总结了现代微观测试手段对C-S-H纳米模型的验证结果,分析了当前研究存在的问题并对今后研究提出了建议。 相似文献
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为探究水化硅酸钙(C-S-H)晶核剂对掺减水剂混凝土的影响,研究了不同钙硅比的水化硅酸钙对聚羧酸减水剂的吸附性能.通过120℃水热反应法制备水化硅酸钙,并采用XRD、SEM和29Si NMR对所制备的Ca/Si为1.0、1.3和1.6的水化硅酸钙样品进行表征;同时通过Zeta电势、总有机碳分析(TOC)和流动性分析探究了由钙硅比的变化对水化硅酸钙的Zeta电势和减水剂吸附性能以及对水泥浆体流动度的影响.试验结果表明,水化硅酸钙的链长和结晶度的优劣主要受到钙硅比的影响,钙硅比增大,链长变短,结晶度变差;水化硅酸钙的Zeta电势随着钙硅比增加而增大;C-S-H在超纯水中的电导率随钙硅比增加而变大;在不同氢氧化钙浓度的溶液中,Ca/Si为1.6的样品较1.0样品能吸附更多的减水剂;并且拥有较好的浆体流动性能.因此,高钙硅比的水化硅酸钙对聚羧酸减水剂拥有较强的吸附能力,并且对含聚羧酸减水剂的水泥浆体流动性能影响相对较小. 相似文献
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水热合成水化硅酸钙(C-S-H)的制备与表征 总被引:1,自引:0,他引:1
本论文以高纯氧化钙与白炭黑为原料,通过水热法合成了水化硅酸钙(C-S-H).采用XRD、SEM对分别选取温度为100℃、120℃、150℃、180℃水热反应6h的水化硅酸钙样品,与150℃分别反应2h、6h、10 h的样品做了物相变化与显微结构的分析,结果表明在低于120℃时产物为结晶度较低的凝胶,随着温度的升高,水化硅酸钙凝胶的结晶度逐渐提高,在150℃和180℃时,生成结晶度较高的托勃莫来石和硬硅钙石;反应时间从6h延长到10h只提高了晶体的结晶度,而没有改变晶体结构.这一结果对改善蒸压制品的蒸压制度具有重要的指导意义. 相似文献
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D. S. SNELL† 《Journal of the American Ceramic Society》1975,58(7-8):292-295
The investigation and characterization of tobermorites and the synthetic hydrates C-S-H(I) and C-S-H gel are reviewed, with particular attention to the application of X-ray diffractometry, ir spectrophotometry, electron microscopy, and differential thermal analysis. 相似文献
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Poly(o-toluidine dihydrochloride): Spectral Characterization and Synthesis of Eskolite Nanoparticles
Nasser Mohammed Hosny Ghada Samir Mohamed Shafick Zoromba Samir Alghool 《Polymer-Plastics Technology and Engineering》2017,56(4):435-442
Poly(o-toluidine?·?2HCl) and its doped polymers with Mn and Cr ions have been synthesized and characterized by FT-IR, UV–Vis. and thermogravimetrical analyses. Potassium dichromate has been used as an initiator and a dopant of chromium in CrPOT preparation. The effect of doping on thermal and optical properties of Poly(o-toluidine dihydrochloride) has been discussed.CrPOT has been used as a precursor of Cr2O3 nanoparticles through thermal decomposition rout. The obtained nanoparticles have been characterized by X-ray diffraction and high resolution transmission electron microscope. The results indicated that Cr2O3 exists in hexagonal structure as mesoporous Eskolit with average particle size of 48?nm. Optical band gap measurements indicated that Eskolite nanoparticles have wider band gap than the bulk. 相似文献
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Calcium silicate hydrate (C-S-H) can be viewed as a solid solution, 0.833Ca(OH)2 .SiO2 .0.917H2 O-xCa(OH)2 , at equilibrium at 30°C. On this basis, the change in Gibbsfree energy (ΔGr ) in the solid-solution reaction was calculated from solubility duta for C-S-H in water. The change in ΔGr with real ratio decreased notably for the higher calcium contents (CaO/Si02 1.7; ×0.867). Thermochemical values for C-S-H (CaO/SiO2 =1.7) were estimated to be ΔH°=-2890 kJ/mol, ΔG°=-2630 kJ/mol, and S°=200 J1/mol.K at 298 K . 相似文献
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FREDRIK P. GLASSER ERIC E. LACHOWSKI DONALD E. MACPHEE 《Journal of the American Ceramic Society》1987,70(7):481-485
A compositional model based on available structural evidence is proposed for amorphous calcium silicate hydrogel. It is applicable to gels in the (Ca/Si),solid range 1.0 to 1.4 and is formulated to take account of dimeric silicate species in the solid. Its composition is represented by Ca x H6−2 x Si2 O7 · z Ca(OH)2 · n H2 O where x and z are not independently obtainable; x + z , however, is evaluated from the Ca/Si ratio. The model is applied to representative solubility data; Ksp and free energies of formation for C-S-H's in this composition range are evaluated. 相似文献
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P. Ionita C. Ghica M. T. Caproiu G. Ionita 《Journal of Inorganic and Organometallic Polymers and Materials》2008,18(3):414-419
Water-soluble gold nanoparticles, capped with captopril, have been synthesized and characterized. Their average size is 2.3 nm,
with a spherical shape. These gold nanoparticles can be easily labeled with stable free radicals (4-amino-tempo) by a coupling
reaction performed in the presence of 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ). Both synthesized and spin-labeled
gold nanoparticles can be incorporated into much bigger (100 nm) silica nanoparticles using the Stober method, thus forming
hybrid metal (gold)-inorganic (silica) nanoparticles. These hybrid silica nanoparticles (containing or not spin-labeled gold
nanoparticles) can be easily spin-labeled with another stable free radical (4-isocyanato-tempo), leading to the formation
of a double spin-labeled material. In this way, some stable free radicals are attached on the gold surface while others are
attached on the silica surface. Three types of EPR spectra were recorded and discussed for the hybrid gold-silica nanoparticles:
(1) where the spin labels are attached to the embedded gold nanoparticles, (2) where the spin labels are attached to the silica
nanoparticles, and (3) in the case of the double spin labeled material where both gold and silica nanoparticles are spin-labeled.
Influence of different solvents on the EPR spectra is also discussed. 相似文献
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Shumei Wang Guangjun Zhou Mengkkai Lu Yuanyuan Zhou Shufen Wang Zhongsen Yang 《Journal of the American Ceramic Society》2006,89(9):2956-2959
Phase-pure lanthanum stannate (La2 Sn2 O7 ) nanoparticles with a pyrochlore structure were produced by a simple coprecipitation method for the first time. The optical properties of La2 Sn2 O7 synthesized by different conditions were investigated. They had different photoluminescence intensities around 400 nm at the same excitation wavelength. The size of La2 Sn2 O7 nanoparticles synthesized by the reverse-drop method was smaller than those synthesized by the nature-drop method. The nanoparticles became large rapidly with the dilution of the original reagent solution. 相似文献