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分选与磨细粉煤灰对水泥胶砂性能的影响 总被引:1,自引:0,他引:1
研究了分选与磨细粉煤灰的颗粒分布与形貌的差异及对水泥胶砂性能的影响。研究结果表明:当勃氏比表面积相近,磨细粉煤灰的中位粒径大于分选细粉煤灰,其圆珠状颗粒较少,表面较为粗糙。在相同水胶比的条件下,掺分选粗粉煤灰的水泥胶砂流动度及强度均低;分选粗粉煤灰磨细后,不仅减少了颗粒的粘连,增加了比表面积,而且提高了粉煤灰的反应活性和水泥胶砂流动度及强度,虽其水泥胶砂流动度仍小于掺分选细粉煤灰的水泥,3d水泥胶砂强度也略低,但其28d水泥胶砂强度略高于掺分选细粉煤灰的水泥;在相同水泥胶砂流动度的条件下,掺磨细粉煤灰配制的水泥胶砂3d强度低于掺分选细粉煤灰的水泥,但随着水化龄期的增长,其差距逐步缩小,至60d时可超过后者。 相似文献
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高钙粉煤灰-水泥体系细度匹配与胶砂强度关系的试验研究 总被引:1,自引:0,他引:1
将高钙粉煤灰与纯水泥分别粉磨至不同的细度 ,然后分别与纯水泥按 1∶1的比例配成高钙粉煤灰水泥 ,进行龄期抗压强度试验。运用origin软件 ,以水泥与高钙粉煤灰比表面积之差S 为x轴 ,以它们混合后的比表面积S为y轴 ,以高钙粉煤灰 -水泥试样的抗压强度为z轴 ,进行三维区域图分析 ,给出各项性能指标发展趋势与水泥、高钙粉煤灰的相对位置以及混合体系总体细度的相互关系 ,进而考察高钙粉煤灰与水泥的细度匹配 ,并用高钙粉煤灰早期化学结合水量方法测定各匹配的高钙粉煤灰水泥的早期水化速度 ,以证实其宏观结果 相似文献
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Jatuphon Tangpagasit Chai Jaturapitakkul Kraiwood Kiattikomol 《Cement and Concrete Research》2005,35(6):1145-1151
This research is to study the effect of particle size of fly ash on packing effect and pozzolanic reaction of mortar when 20% of fly ash is used to replace Portland cement type I. Both effects can be determined by using fly ash and insoluble material which have almost the same particle size to replace Portland cement type I. Normally, the compressive strength of fly ash mortar is contributed from hydration reaction, packing effect, and pozzolanic reaction. For mortar mixed with insoluble material, the compressive strength is due to hydration reaction and packing effect. Thus, compressive strength due to pozzolanic reaction can be determined from the difference in compressive strength between fly ash mortar and insoluble material mortar. The results show that the strength activity index of fly ash mortar depends on the median particle size of fly ash and curing ages of mortar samples. At early ages, the strength activity index of fly ash mortar due to packing effect is higher than that due to pozzolanic reaction. At the ages of 3 to 90 days, the difference in strength activity index due to packing effect of fly ashes with median particle size of 2.7 and 160 μm is almost constant about 22% of the strength of standard mortar (STD). The differences in strength activity index due to pozzolanic reaction of fly ashes with median particle size of 2.7 and 160 μm are 3%, 20%, and 27%, respectively, at the ages of 3, 28, and 90 days. 相似文献
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The effect of fineness of fly ash on mechanical properties and alkali–silica reaction resistance of cement mortar mixtures incorporating fly ash has been investigated within the scope of this study. Blaine fineness of fly ash has been increased to 907 m2/kg from its original 290 m2/kg value by a ball mill. Test samples were prepared by replacing cement 20, 40 and 60%, with finer and coarser fly ashes and kept under standard and steam curing conditions until testing. Test results showed that grinding process improved the mechanical properties of all samples significantly. The beneficial effect of grinding fly ash, may increase utilization of this by-product in precast and ready-mix concrete industries. Incorporation of fly ash with different fineness values and ratios also decreased the expansions to harmless levels of cement mortars due to alkali–silica reaction. 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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通过筛分和破碎两种方式分别获得粒径区间为0.6~1.18 mm、0.3~0.6 mm的粉煤灰渣,并用其等体积替代对应粒径区间的细骨料,分析粉煤灰渣对砂浆工作性和强度的影响,探究粉煤灰渣的最优替代粒径区间。结合扫描电镜(SEM)、能谱分析(EDS)等方法分析了粉煤灰渣替代细骨料后砂浆试件的强度变化机理。基于砂浆最优替代粒径区间结果,验证了砂浆混凝土试件的强度和抗冻性。研究结果表明:分别以筛分方式和破碎方式得到的0.3~0.6 mm粒径区间粉煤灰渣替代对应区间细骨料后,其砂浆试件强度均与基准组(未替代)基本一致;而以筛分方式得到的0.3~0.6 mm粒径区间粉煤灰渣替代对应区间细骨料后,其混凝土试件强度和抗冻性与基准组基本一致。在水泥提供的氢氧化钙环境下粉煤灰渣表面生成水化硅酸钙,从而增加了水泥和粉煤灰渣界面胶结强度,强化水泥与粉煤灰渣界面区域,凹凸不平的粉煤灰渣表面与水泥浆咬合嵌锁,保证了试件的强度。 相似文献
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为循环利用岩棉生产过程中排出的炉渣废料,将其磨成3个细度的粉体,分别与岩棉纤维粉、粉煤灰和粒化高炉矿渣粉(简称矿粉)进行对比分析.结果表明:炉渣主要化学成分及含量接近粉煤灰.炉渣中玻璃体含量较高,同时存在少量结晶相,结晶度为5.28%.提高炉渣粉磨细度可显著增加活性.450 kg/m2比表面积的炉渣粉强度活性指数比粉煤灰高出约10%,低于同等细度的矿粉.掺入炉渣粉的水泥砂浆试件抗渗和抗冻性优于粉煤灰砂浆,而低于矿粉砂浆试件.孔结构测试分析表明,炉渣粉水泥砂浆孔隙率和多害孔含量介于矿粉水泥砂浆和粉煤灰水泥砂浆之间.粉磨制备的岩棉炉渣粉体具备作为矿物掺合料的可行性. 相似文献
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The effects of high temperature on the mechanical properties of cement based mortars containing pumice and fly ash were investigated in this research. Four different mortar mixtures with varying amounts of fly ash were exposed to high temperatures of 300, 600, and 900 °C for 3 h. The residual strength of these specimens was determined after cooling by water soaking or by air cooling. Also, microstructure formations were investigated by X-ray and SEM analyses.Test results showed that the pumice mortar incorporating 60% fly ash revealed the best performance particularly at 900 °C. This mixture did not show any loss in compressive strength at all test temperatures when cooled in air. The superior performance of 60% FA mortar may be attributed to the strong aggregate-cement paste interfacial transition zone (ITZ) and ceramic bond formation at 900 °C. However, all mortar specimens showed severe losses in terms of flexural strength. Furthermore, specimens cooled in water showed greater strength loss than the air cooled specimens. Nevertheless, the developed pumice, fly ash and cement based mortars seemed to be a promising material in preventing high temperature hazards. 相似文献
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为了提高抹灰砂浆的强度和体积稳定性,研究了水泥用量和灰渣比(循环硫化床(CFB)飞灰和CFB炉渣的质量比)对CFB灰渣抹灰砂浆2 h稠度损失率、抗压强度和体积稳定性的影响,并采用扫描电子显微镜、X射线能谱仪和X射线衍射仪对砂浆的微观形貌、元素分布和物相组成进行测试表征。结果表明,当水泥用量为5%、8%、12%(质量分数)时,CFB灰渣抹灰砂浆分别达到抹灰砂浆M10、M15、M20的强度等级。当胶凝材料用量一定时,随着水泥用量增大,砂浆2 h稠度损失率减小;当水泥用量一定时,随着灰渣比增大,砂浆2 h稠度损失率增大,膨胀效应减弱。CFB灰渣抹灰砂浆中生成的膨胀性钙矾石有效填充了颗粒之间的孔隙,从而提高砂浆的强度和体积稳定性。 相似文献
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A new way to increase the long-term bond strength of new-to-old concrete by the use of fly ash 总被引:1,自引:0,他引:1
Gengying Li 《Cement and Concrete Research》2003,33(6):799-806
The short-term and long-term bond strengths of new-to-old concrete were experimentally investigated with an emphasis on the influence of new concretes and binders. These new concretes included ordinary Portland cement concrete, expansive concrete and high-volume fly ash concrete, while the binders included pure cement paste (C-binder), expansive binder (E-binder) and fly ash mortar (F-binder). The results showed that the short-term bond strength of all specimens with fly ash concrete was lower than that with ordinary Portland cement concrete, which in turn was lower than that with expansive concrete. The bond strength of the specimens with F-binder was the lowest at the age of 7 days. However, the long-term bond strength of all specimens with added fly ash was the highest and strength losses were observed in the specimens repaired with expansive concrete or E-binder at the age of 3 years. The microstructure of the transition zone with F-binder was also studied by using both scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) at the ages of 28 days and 1 year, respectively. 相似文献
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To enable commercial use of alkali-activated fly ash concrete, its durability must be better understood. Alkali–silica reaction is a primary concern since highly alkaline solutions are generally used for activation. This study investigated the effect of NaOH activating solution concentration on pore solution alkalinity and subsequent alkali–silica reaction in alkali-activated fly ash concrete. It was found that pore solution alkalinity increased with increasing activating solution NaOH concentration, and this effect was amplified at concentrations above an optimum, defined as the concentration that resulted in the highest mortar compressive strength. Expansion of concrete prisms containing highly reactive fine aggregate and activating solution concentrations above the optimum concentration was approximately three times that of concrete with optimum activating solution concentrations, but only about 5% of the expansion observed in the ordinary portland cement control. The low expansion may be attributed to the low calcium levels in the alkali-activated fly ash concrete. 相似文献
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高钙粉煤灰的粉磨改性研究 总被引:1,自引:0,他引:1
研究了粉磨对两种高钙粉煤灰物理化学性能的影响。通过混合水泥雷氏夹膨胀值、强度和自由线膨胀率等的试验测定,对两种高钙粉煤灰经粉磨后进行性能研究。结果表明,通过粉磨可以减缓甚至消除高钙粉煤灰带来的安定性问题,提高混合水泥强度,降低混合水泥自由线膨胀率。 相似文献