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复合胶凝材料的初期水化产物和浆体结构 总被引:3,自引:0,他引:3
利用XRD和ESEM研究了由硅酸盐水泥、矿物掺和料和膨胀剂组成的复合胶凝材料的初期水化产物和浆体结构。结果表明:水化产物在水化6h时刚开始成核生长,生成纤维状CSH晶须和六方片状钙矾石微晶,并有过渡性水化产物钾石膏片状晶体和K2S04生成。复合胶凝材料水化1d后,水化产物大量生成,主要为CSH凝胶、Ca(OH)2和钙矾石,并形成致密的浆体结构。 相似文献
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为研究碱激发磷矿渣复合胶凝材料的水化特性,采用X射线衍射(XRD)、热重差示扫描量热分析(TG DTA)和扫描电子显微镜(SEM)等对磷矿渣被Ca(OH)2、石膏激发后的水化产物以及磷矿渣复合胶凝材料的组成与微结构特征进行了研究.结果表明:在Ca(OH)2激发作用下磷矿渣能较好地发挥潜在活性,且其活性随着比表面积的增大和龄期的延长而逐渐增大;在Ca(OH)2和石膏的共同激发作用下磷矿渣能提前发挥潜在活性,提高其水化程度;磷矿渣可提高水泥的水化程度,且比表面积越大、龄期越长,对水泥水化程度的促进越显著. 相似文献
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将湖、河淤泥焚烧后的残渣灰(淤泥焚烧灰,简称焚烧灰)在建材领域进行资源化处置,对比了焚烧灰与粉煤灰的火山灰活性,探讨了养护龄期、焚烧灰掺量和水胶比对水泥-焚烧灰复合胶凝材料净浆硬化浆体(简称为硬化浆体)抗压强度的影响;对比了焚烧灰与粉煤灰对新拌砂浆流动性的影响,探讨了焚烧灰掺量对砂浆流动性的影响规律;采用X射线衍射仪(XRD)和扫描电镜(SEM)研究了硬化浆体的微观结构.结果表明:焚烧灰的28 d抗压强度活性指数达到83%,可作为部分替代硅酸盐水泥的胶凝材料使用;随着焚烧灰掺量的增加,含焚烧灰新拌砂浆的流动性显著下降,硬化浆体的抗压强度早期下降明显,但后期有所提高;当焚烧灰掺量为20%时,硬化浆体的抗压强度达到最大值;水胶比越小,焚烧灰对硬化浆体抗压强度的影响越显著;焚烧灰的火山灰活性促进了复合胶凝材料后期的水化反应. 相似文献
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高性能复合胶凝材料流变性试验研究 总被引:8,自引:0,他引:8
对高性能混凝土常用原矿物掺和料(粉煤灰、矿渣、硅灰)的动电电位进行了研究,测定了减水剂对矿物掺和料动电电位的影响,并研究了不同掺和料两两相互掺入水泥后,在减水剂作用下复合胶凝材料的流变性能,结果表明:不同的矿物掺和料其化学成分、细度、密度决定了各自动电电位;减水剂对矿物掺和料动电电位影响不尽相同;复合胶凝材料的流变性与矿物掺和料的品种、细度、复掺量以及减水剂和水胶比的组合是密切相关的。 相似文献
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基于最优化方法,给出使用同轴双圆柱流变仪来获取胶凝材料浆体的Bingham流变参数的途径;探究五种矿物掺合料(粉煤灰、矿渣粉、硅灰、石英粉、粉煤灰微珠)和两种化学外加剂(减水剂与引气剂)对胶凝材料浆体流变参数的影响。研究结果表明:矿物掺合料等体积替代水泥相对于等质量替代水泥,对降低浆体的屈服应力和塑性黏度有利。粉煤灰可降低浆体的屈服应力和塑性黏度;矿渣粉和石英粉可降低高水胶比浆体的屈服应力和塑性黏度,但增大低水胶比浆体的屈服应力和塑性黏度;硅灰可显著提升浆体的屈服应力;粉煤灰微珠可降低浆体的塑性黏度但增大其屈服应力。减水剂可降低浆体的屈服应力和塑性黏度;引气剂可降低浆体的塑性黏度。矿物掺合料和化学外加剂对胶凝材料浆体的Bingham流变参数的影响,取决于水胶比、矿物掺合料或化学外加剂的掺量、矿物掺合料颗粒粒径、粒形和水化活性等因素,因此使得胶凝材料浆体的流变参数随着矿物掺合料和化学外加剂种类和掺量的变化,表现出非线性特征。 相似文献
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低水胶比时水泥-粉煤灰复合胶结材的水化性能 总被引:8,自引:1,他引:8
研究了水泥粉煤灰复合胶凝材料在低水胶比条件下的水化产物与硬化浆体显微结构,探讨了高效减水剂对复合胶凝材料的水化产物、水化程度、硬化浆体显微结构的影响.水泥粉煤灰复合胶凝材料的水化产物与普通硅酸盐水泥相同.球形的粉煤灰微粒在浆体中起到微集料的作用,在低水胶比条件下,有助于改善新拌浆体的流动性与硬化浆体的断裂性能,提高其强度.掺有FDN的复合胶凝材料其初期水化程度并不因表观水胶比低而降低.水泥粉煤灰复合胶凝材料与高效减水剂协同作用,在低水胶比条件下能获得较好的力学性能. 相似文献
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低水胶比时水泥—粉煤灰复合胶结材料的水化性能 总被引:4,自引:0,他引:4
研究了水泥-粉煤灰复合胶凝材料在低水胶比条件下的水化产物与硬化浆体显微结构,探讨了高效减水剂对复合胶凝材料的水化产物,水化程度,硬化浆体显微结构的影响,水泥-粉煤灰复合胶凝材料的水化产物与普通硅酸盐水泥相同,球形的粉煤灰微粒在浆体中起到微集料的作用,在低水前比条件下,有助于改善新2浆体的流动性与硬化浆体的断裂性能,提高其强度,掺有FDN的复合胶凝材料其初期水化程度并不因表观水胶比低而降低,水泥-粉煤灰复合胶凝材料与高效减水剂协同作用,在低水胶比条件下能获得较好的力学性能。 相似文献
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Evaluation of calcium hydroxide contents in pozzolanic cement pastes by a chemical extraction method
The aim of the study is to investigate the calcium hydroxide (Ca(OH)2) contents in pozzolanic cement pastes analyzed by the chemical extraction method and thermal analysis (DTA/TG). The second part of the study involves the carbonation of pozzolanic cement pastes and its influence on Ca(OH)2 reduction. The Ca(OH)2 contents in cement pastes after being subjected to accelerated carbonation were investigated by a chemical extraction method and compared to those values from DTA/TG analysis. The experimental results show that the chemical method reveals overall results comparable to those from DTA/TG analysis. However, in case of pastes containing high amounts of mineral admixtures or pastes subjected to carbonation which contain very low Ca(OH)2, only the chemical method yields precise reliable results by showing the pseudo-negative contents. 相似文献
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Wunchock Kroehong Theerawat Sinsiri Chai Jaturapitakkul Prinya Chindaprasirt 《Construction and Building Materials》2011,25(11):4095-4104
This paper presents the effect of palm oil fuel ash fineness on the microstructure of blended cement paste. Palm oil fuel ash (POFA) was ground to two different finenesses. Coarse and high fineness palm oil fuel ash, with median particle sizes of 15.6 and 2.1 μm, respectively, were used to replace ordinary Portland cement (OPC) at 0%, 20% and 40% by binder weight. A water to binder (W/B) ratio of 0.35 was used for all blended cement pastes. The amorphous ground palm oil fuel ash was characterized by the Rietveld method. The compressive strength, thermogravimetric analysis and pore size distribution of the blended cement pastes were investigated. The test results indicate that the ground palm oil fuel ash was an amorphous silica material. The compressive strengths of the blended cement pastes containing coarse POFA were as high as that of OPC cement paste. Blended cement paste with high fineness POFA had a higher compressive strength than that with coarse POFA. The blended cement pastes containing 20% of POFA with high fineness had the lowest total porosity. The Ca(OH)2 contents of blended cement paste containing POFA decreased with increasing replacement of POFA and were lower than those of the OPC cement paste. In addition, the POFA fineness had an effect on the reduction rate of Ca(OH)2. Furthermore, the critical pore size and average pore size of blended cement paste containing POFA were lower than those of the OPC cement paste. The incorporation of high fineness POFA decreased the critical pore size and the average pore size of blended cement paste as compared to that with coarse POFA. 相似文献
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采用水泥、单一外加剂和复合外加剂对高含水粘土进行固化试验,并运用X射线衍射和扫描电子显微照相等对加固土进行了分析。研究结果表明,当土壤含水量较高(48%左右)时,在水泥中掺14%的石膏及3%的硫酸钠,能大幅度提高固化土的强度;在硫酸盐外加剂的作用下,粘土中的活性氧化铝与Ca(OH)2反应生成针状的钙矾石晶体,从而使土团与水化产物相互联接,大大提高稳定土的强度和水稳性;较多的钙矾石晶体的形成是硫酸盐外加剂能大幅度提高固化土强度的主要原因。 相似文献
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利用XRD、DSC/TG、SEM/EDS和显微硬度等测试手段时电场作用后砂浆内部预埋水泥净浆的组成和微观结构进行了分析.结果表明:电场作用的初期,阴极附近生成大量结晶较好的Ca(OH)<,2>,且取向性指数大;然而随着通电时间的延长,Ca(OH)<,2>的生成趋于稳定,且取向性指数逐渐减小;阴极附近试样的显微硬度呈现先... 相似文献