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在普通硅酸盐水泥砂浆中加入济钢产超细矿渣,研究不同掺量的超细矿渣对水泥浆体凝结时间及胶砂流动度、强度的影响.实验结果表明:随着掺量的提高,水泥浆体的初凝时间延长,终凝时间缩短;胶砂流动度随超细矿渣掺量的增大而减小;随超细矿渣掺量的增大,水泥胶砂的3d和28 d强度提高,当质量分数掺量为30%时,水泥砂浆28 d的抗折、抗压强度达到最大,分别达到9.65 MPa和68.44 MPa. 相似文献
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以比表面积为413 m2/kg、521 m2/kg、846 m2/kg、1241m2/kg的石灰石粉和32.5级复合硅酸盐水泥为研究对象,将不同细度的石灰石粉以0%、5%、10%、15%、20%、30%的比例等质量取代P.C32.5水泥,对比研究了石灰石粉对P.C32.5水泥凝结时间、标准稠度、需水比以及砂浆强度的影响。结果表明:掺加石灰石粉可以降低水泥的标准稠度需水量,石灰石粉的比表面积越大,水泥的需水量比越小;石灰石粉对水泥的凝结时间影响较小;对水泥胶砂的早期强度影响较大;石灰石粉的颗粒越小,对水泥的性能越有利。依据试验结果,石灰石粉做混合材时,可将其掺量放宽到20%。 相似文献
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对不同粉磨细度、不同品质的电炉磷渣粉对水泥性能影响及其活性改良进行了研究比较。结果表明,磷渣粉比表面积由300 m~2/kg增至600 m~2/kg,水泥后期强度显著提高,磷渣粉中玻璃体含量高和P_2O_5含量较低时水泥28 d强度与同掺量矿渣水泥强度接近,90 d时甚至超过矿渣水泥;随着磷渣粉比表面积增大及其掺量的增加,水泥凝结时间显著延长;磷渣粉细度变化对水泥胶砂流变性没有较大影响,水泥与外加剂相容性有所改善;磷渣粉中少量钙质和硅铝质改良材料的掺加,可显著缩短磷渣水泥凝结时间,有利于促进水泥早期及后期强度的发展,并可有效降低混凝土收缩率。 相似文献
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粉煤灰对水泥胶砂性能影响的试验研究 总被引:2,自引:2,他引:2
通过研究粉煤灰掺量和细度、龄期等因素对水泥胶砂流动性能、强度性能和吸水性能的影响,得出粉煤灰在上述因素下对水泥胶砂性能的影响规律。结果表明:在试验范围内,随粉煤灰掺量或比表面积增加,水泥砂浆流动性增大,需水量降低,即粉煤灰具有良好的增塑效应;随着粉煤灰掺量的增加,水泥胶砂早期强度降低,后期强度增加较快.其吸水率呈减少的趋势,这有利于抗渗性的提高;粉煤灰比表面积愈大,水泥胶砂的强度愈高,吸水率也愈小。 相似文献
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将400、450、500m^2/kg三个细度的钢渣微粉与细度为450m^2/kg的矿渣复合成为双掺料,配制成复合水泥。试验表明:该水泥的标准稠度需水量随钢渣掺量增加呈减小的趋势,终凝时间则逐渐延长。当钢渣掺量不变时,提高钢渣微粉的细度,水泥的标稠需水量变化不大。随钢渣掺量增加,水泥各个龄期的抗压和抗折强度呈下降趋势。在相同的掺量条件下,钢渣粉细度为400m^2/kg比表面积、掺量为10%时,28d抗压强度明显降低。提高钢渣粉细度,28d抗压和抗折强度总体上呈增加的趋势。将450m^2/kg比表面积的钢渣微粉与矿渣微粉复合为双掺料,是经济可行的技术方案。 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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对潞安煤经循环流化床、煤粉炉和气化炉处理后得到的煤灰进行了化学组成、矿物组成、特征基团、粒径分布、比表面积及微观形貌等理化性质的对比研究,并考察了其在酸浸和碱浸过程中Al^3+,Si^4+,Fe^3+,Ca^2+,K^+和Ti^4+等离子的溶解特性。结果表明:不同炉型潞安煤灰中铝、钙、硫等元素的含量有明显的差异;矿物组成包括晶相的鳞石英、方石英、莫来石、硬石膏及非晶相的偏高岭石、假莫来石、无定型二氧化硅等;相比较而言,气化炉灰中铝硅酸盐矿物结构更加不稳定。循环流化床灰颗粒呈具有一定孔洞结构的不规则状,而煤粉炉灰和气化炉灰均为光滑球形颗粒,循环流化床灰的粒径>煤粉炉灰的粒径>气化炉灰的粒径,循环流化床灰的比表面积>气化炉灰的比表面积>煤粉炉灰的比表面积。在HCl溶液中,Al^3+,Fe^3+,Ca^2+,K^+,Ti^4+的溶出率均较高;在NaOH溶液中,仅Si^4+和K^+的溶出率较高。不同炉型潞安煤灰中各元素的溶出率具有较大差异,主要与其矿物组成、结构稳定性、粒径和比表面积等相关。 相似文献
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Luisa Barbieri Anna Corradi Isabella Lancellotti Antonio Pedro Novaes De Oliveira Orestes Estevam Alarcon 《Journal of the American Ceramic Society》2002,85(3):670-674
The nucleation and growth of diopside Ca(Mg,Al)(Si,Al)2 O6 crystals on the free surface of a 24 wt% MgO, 14 wt% CaO, 9 wt% Al2 O3 , and 53 wt% SiO2 glass, with a 2 wt% addition of steel fly ash, were investigated through DTA, XRD, SEM, and optical microscopy. Crystallization was complete at ∼920°C with an activation energy of 589 kJ/mol. Samples with polished free surfaces were nucleated at selected temperatures in the range of 730° to 820°C, and then heat-treated at 870°C for 15 min for crystal growth. Nucleation was predominantly observed at the surface, and the number of diopside crystals per unit of area and the mechanism of crystallization were determined. It was concluded that nucleation reaches a maximum at 750°C, corresponding to an average density of diopside crystals of 8.4 × 106 nuclei/cm2 , and that between 900° and 1100°C, a uniformly crystallized layer is formed at an exponential rate. The crystallized volume fraction increased significantly in the 880°–890°C growth range, and remained almost constant at higher temperatures. In the 860°–910°C range, the size of the diopside crystals formed in the samples nucleated at the temperature of the maximum nucleation rate, and linearly increased, reaching values between 1.0 and 3.0 μm at 870° and at 910°C, respectively. 相似文献
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The kinetics of aluminium extraction were investigated, using as-received and calcined fly ash samples and a pure culture of Aspergillus niger. This fungus metabolized sucrose to citric and oxalic acids, which were involved in the acidolysis of fly ash. Aluminium extraction from as-received fly ash was only 5–8%, whereas from calcined fly ash it was up to 93.5%. The order of reaction and the overall reaction rate constant were determined by the van't Hoff technique with respect to the concentration of calcined fly ash. A linearized form of a modified Monod expression was applied to the experimental data to assess the kinetic constants for the acidolysis process. Statistically designed experiments were carried out with calcined fly ash and synthetic solutions containing citric and oxalic acids to determine the optimum leaching conditions. The acidolysis reaction mechanism is discussed. 相似文献
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Soluble silica has a very significant effect on the microstructural and mechanical development of the cementitious materials produced as a result of the alkali activation of fly ash. In this study, four different alkaline solutions with different soluble silica contents were used to activate fly ash. The primary reaction product was a sodium aluminosilicate gel, while different types of zeolites appeared as minority phases. The percentage and composition of these reaction products were found to depend on both the soluble silica content present in the activating solutions and the thermal curing time. In addition, the amount of gel was observed to have a decisive effect on the mechanical strength developing in the material. 相似文献
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Vernon S. Somerset Leslie F. Petrik Richard A. White Michael J. Klink David Key Emmanuel I. Iwuoha 《Fuel》2005,84(18):2324-2329
A co-disposal reaction was used wherein fly ash (FA) was reacted with acid mine drainage (AMD), to collect filtrates for zeolite synthesis. Raw fly ash as well as fly ash leached with HCl were subjected to the same alkaline hydrothermal zeolite synthesis conditions, as for the co-disposal filtrates, in order to evaluate the zeolitic material obtained. The Si and Al contents of the fly ash (FA) filtrates were used as precursor species for the alkaline hydrothermal conversion of the fly ash filtrates into zeolites. These filtrates were then analysed by XRF spectrometry for quantitative determination of SiO2 and Al2O3. The [SiO2]/[Al2O3] ratio obtained in the filtrates range from 1.4 to 2.5. The [SiO2]/[Al2O3] ratio was used to predict whether the fly ash filtrates could successfully be converted into faujasite zeolitic material by the adopted synthesis procedures. If the [SiO2]/[Al2O3] ratio is higher than 1.5 in the co-disposal filtrates, it favours the formation of faujasite. The zeolite synthesis included an alkaline fusion of the co-disposal filtrates, followed by aging for 8 hours and hydrothermal conversion by crystallisation at 100 °C. Different variables were investigated during the synthesis of zeolite to ascertain their influence on the end product. These variables include adding different amounts of deionised water to the FA-related starting material, using different compositions of FA related starting material and different FA:NaOH ratios in fusing the starting material. 相似文献
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H. Liu M.Y. Liang C.S. Liu Y.X. Gao J.M. Zhou 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2009,153(1-3):131-137
This study demonstrated that coal ash, as widely distributed solid waste disposal, would function as a media for organic pollutants removal in the presence or absence of H2O2/O3 under ultrasonic radiation. Coal ash could act as a catalyst to generate OH radicals with the presence of H2O2/O3 and consequently enhance the phenol degradation. Experimental results showed that when using coal ash as a catalyst under ultrasonic irradiation, 83.4% and 88.8% of phenol was degraded in the presence of H2O2 or O3, respectively. The degradation rate of phenol would increase with increasing amount of O3, while there was an optimal concentration of H2O2 (1.5 mM) for phenol degradation. Higher dosage of coal ash could result in higher phenol degradation rates. H2O2/coal ash/ultrasonic system could achieve better performance for phenol degradation under more acidic conditions, while more alkaline condition in O3/coal ash/ultrasonic system favored phenol degradation. This study provides a new approach for wastewater treatment especially when contaminated with phenolic pollutants. 相似文献
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Sorbents for semidry-type flue gas desulfurization (FGD) process can be synthesized by mixing coal fly ash, calcium oxide, and calcium sulfate in a hydration process. As sorbent reactivity is directly correlated with the specific surface area of the sorbent, reacting temperature, concentration of the reacting gas species and relative humidity, two major aim in the development of a kinetic model for the FGD process are to obtain an accurate model and at the same time, incorporating all the parameters above. Thus, the objective of this work is to achieve these two aims. The kinetic model proposed is based on the material balance for the gaseous and solid phase using partial differential equations incorporating a modified surface coverage model which assumes that the reaction is controlled by chemical reaction on sorbent grain surface. The kinetic parameters of the mathematical model were obtained from a series of experimental desulfurization reactions carried out under isothermal conditions at various operating parameters; inlet concentration of SO2 (500 ppm C0,SO2 2000 ppm), inlet concentration of NO (250 ppm CO,NO 750 ppm), reaction temperature (60 °C T 80 °C) and relative humidity (50% RH 70%). For a variety of initial operating conditions, the mathematical model is shown to give comparable predictive capability when used for interpolation and extrapolation with error less than 7%. The model was found useful to predict the daily operation of flue gas desulfurization processes by using CaO/CaSO4/coal fly ash sorbent to remove SO2 from flue gas. 相似文献
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