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为探明石灰岩、花岗岩、石英岩和凝灰岩石粉用作混凝土矿物掺合料的可行性,采用X射线衍射仪、Zeta电位仪和总有机碳分析仪分别测定了不同岩性石粉的矿物组成、Zeta电位和减水剂吸附率,研究了石粉-水泥二元复合胶凝材料和石粉-粉煤灰/矿渣粉-水泥三元复合胶凝材料净浆和胶砂的工作性能和力学性能.结果表明:石粉的矿物组成对Zeta电位和减水剂吸附率影响较大,沸石矿物疏松结构使凝灰岩石粉的Zeta电位和减水剂吸附作用随时间变化明显,云母矿物的插层吸附使花岗岩石粉对减水剂的吸附作用明显.不同岩性石粉对复合胶凝材料浆体工作性能的影响与石粉对减水剂的吸附性能密切相关.不同岩性石粉-水泥复合胶凝材料胶砂的抗压强度比和抗折强度比均高于60%,且石粉增加了水泥胶砂的折压比,提高了胶砂试件的韧性. 相似文献
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研究了不同水胶比下外加剂掺量对胶凝材料净浆流动度的影响,以及净浆流动度、中砂/净浆质量比双因素耦合作用下再生粗骨料裹覆砂浆厚度的变化规律;建立了胶凝材料净浆流动度与外加剂掺量,再生粗骨料裹覆砂浆厚度与净浆流动度、中砂/净浆质量比两个数学关联模型,并将两个数学关联模型应用到透水混凝土配合比设计中.结果表明,再生粗骨料裹覆砂浆厚度随砂浆流动度减小而增大,且骨料粒径愈大,其裹覆厚度愈大.采用再生骨料RCA-9.5配制含砂透水混凝土,其砂浆浆体稳定包裹再生粗骨料,无漏浆封底、露骨散架等问题;混凝土试件28 d抗压强度为14.1~17.1 MPa,28 d抗折强度为2.0~2.7 MPa,透水系数大于6 mm·s-1,抗冻性和耐磨性良好. 相似文献
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《材料研究学报》2017,(9)
以钢渣、矿渣和脱硫石膏为主要原料制备胶凝材料,使用XRD、IR、TG-DTA和SEM等手段探究胶凝材料的水化反应机理,研究了钢渣掺量对全固废混凝土强度的影响,以及胶凝材料浆体的p H值和代表性离子浓度的变化规律。结果表明,当原料质量比为m(钢渣):m(矿渣):m(石膏)=30:58:12时,全固废混凝土3 d、7 d和28 d可以获得较优的强度。随着反应龄期的增加胶凝材料水化溶液的pH值先减小后增大,Ca2+浓度和硅(铝)溶解物的早期浓度较低,后期浓度有所提高。在脱硫石膏的激发下钢渣和矿渣相互促进水化,水化产物以钙矾石(AFt)和水化硅酸钙(C-S-H)凝胶为主。在反应的后期,水化产物的数量迅速增加。针棒状的AFt晶体穿插在C-S-H凝胶内,使硬化浆体的结构更加致密。 相似文献
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结构开裂问题一直困扰着现代混凝土工程,引起混凝土结构开裂的因素有很多,其中水泥的"三高"问题,即高硅酸三钙、高铝酸三钙、高细度是引起开裂的主要原因.本通过降低胶凝材料中水泥熟料的比例、采用粗磨而成的水泥熟料以及提高胶凝材料中矿物掺和料比例的方法配制出低碳胶凝材料这种新型胶凝材料体系,并将其与现行搅拌站常用胶凝材料体系进行抗裂性能的对比,应用自主研发设计的"方圆抗裂模具"研究两种胶凝材料体系的抗裂性能,同时结合水化热做进一步的分析.研究表明:低碳胶凝材料这种新型胶凝材料体系所体现的抗裂性能和当前搅拌站所采用的胶凝材料体系进行比较具有非常大的优势;此外对于低碳胶凝材料而言,它的水化放热量和水化放热速率低于现行搅拌站常用胶凝材料体系;掺加一定量的钢渣、膨胀剂能够显著提高低碳胶凝材料的抗裂性;SO3含量低会增加低碳胶凝材料的开裂敏感性. 相似文献
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采用XRD、IR、TG-DTA、MIP等手段表征赤泥-煤矸石基中钙体系胶凝材料的水化产物及其硬化浆体的孔结构, 研究了解赤泥-煤矸石基中钙体系胶凝材料的水化特性。结果表明, 赤泥-煤矸石基中钙体系胶凝材料的水化产物主要有C-S-H凝胶、钙矾石和Ca(OH)2, 前两者对其强度的发展有促进作用; 水化1 d至90 d其中Ca(OH)2的含量呈先升高后降低的趋势; 随着水化反应的进行在CaO/SiO2比值较低的赤泥-煤矸石基中钙体系胶凝材料中Si-OH基团之间发生聚合反应, 水化产物的聚合度升高; CaO/SiO2比值为0.95和1.04的赤泥-煤矸石基中钙体系胶凝材料的硬化浆体具有较好的孔结构, 而CaO/SiO2比值为1.13的胶凝材料硬化浆体的孔结构相对较差。 相似文献
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Kamlesh Goel 《Scientometrics》2002,55(2):243-258
An analysis of gender differences in psychology in India provides quantitative and qualitative assessment of R&D output contributed by psychologists with the indication of the trend of growth, skewness, relatedness, co-authorship pattern of productivity. 相似文献
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The system for Metrology in Chemistry in Germany is described. At the national standards level, a network of high-level chemistry
institutes coordinated by the national metrology institute, PTB, provides the primary references for chemical measurements.
A dissemination mechanism employs chemical calibration laboratories accredited within the framework of the German Calibration
Service (DKD). They act as “multipliers” between the national standards level and the user level by providing the user with
calibration means which are traceable to the SI via national standards. Traceability structures in clinical chemistry, electrochemistry,
elemental analysis and gas analysis are described 相似文献
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Natural radioactivity in drinking water was determined in population-based random study of 472 private wells. The mean concentrations of (222)Rn, (226)Ra, (234)U, (238)U, (210)Pb and (210)Po in drilled wells were 460, 0.05, 0.35, 0.26, 0.04 and 0.05 Bq l(-1), and in wells dug in the soil were 50, 0.016, 0.02, 0.015, 0.013 and 0.007 Bq l(-1), respectively. Approximately 10% of the drilled wells exceeded a radon concentration of 1000 Bq l(-1) and 18% a uranium concentration of 15 microg l(-1). The mean annual effective dose from natural radionuclides for a drilled well user was 0.4 mSv and 0.05 mSv for a user of a well dug in the soil. The effective dose arising from (222)Rn was 75% of the total of all natural radionuclides for drilled well users. As regards long-lived radionuclides, (210)Po and (210)Pb caused the largest portion of the effective dose. The dose arising from (238)U, (234)U and (226)Ra was only 8% of the total of all natural radionuclides. 相似文献
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Radiation Protection Dosimetry 相似文献
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Dominik Gssi 《真空研究与实践》2005,17(4):186-189
Optical film thickness monitoring is more precise than crystal monitoring. The optical measurement makes use of the fact that the intensity of a monochromatic light beam which is reflected on a film will change periodically with increasing film thickness. The measurement is performed at an exchangeable test glass that is positioned beside the substrates and is therefore coated in the same way as the substrates. The accuracy of cut‐off is achieved by a “fit” of a theoretical curve shape to the measured values. Order filters are used to ensure that, at a certain wavelength, higher deflection orders do not influence the measurement when a monochromator grating is used. 相似文献
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Ali KK 《Radiation protection dosimetry》2012,148(3):372-379
Activity concentrations of (226)Ra, (232)Th and (40)K in 45 samples of different building materials used in Iraq were measured using gamma-spectroscopy system based on high-purity germanium detector with an efficiency of 40 %. Radium equivalent activity, air-absorbed dose rate, annual effective dose, external and internal hazard indices and alpha index due to radon inhalation originating from building materials were measured to assess the potential radiological hazard associated with these building materials. The activity concentrations of the natural radionuclides (226)Ra, (232)Th and 40K were found to range from below detection limit (BDL) to 223.7 ± 9, BDL to 93.0 ± 3 and BDL to 343.1 ± 12, respectively. Values of average radium equivalent activity, air-absorbed dose rate, indoor and outdoor annual effective doses, external and internal hazard indices and alpha index ranged from 6.5 to 124.9, 16.2 to 89.5 (nGy h(-1)), 0.08 to 0.44 mSv, 0.02-0.11 mSv, 0.09 to 0.53, 0.13 to 0.69 and 0.03 to 0.62, respectively. These values indicate a low dose. Therefore, the building materials used in the current study are quite safe to be used as building materials. 相似文献
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