共查询到19条相似文献,搜索用时 203 毫秒
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通过对大掺量粉煤灰水泥与普通硅酸盐水泥配制的混凝土性能进行对比研究,表明大掺量粉煤灰水泥混凝土性能类似于普通水泥混凝土,且具有更好的耐化学侵蚀能力。 相似文献
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通过对大掺量粉煤灰水泥与普通硅酸盐水泥配制的混凝土性能进行对比研究,表明大掺量粉煤灰水泥混凝土性能类似于普通水泥混凝土,且具有更好的耐化学侵蚀能力。 相似文献
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对五岛水泥和小野田水泥的大掺量粉煤灰混凝土进行了抗压强度试验研究.通过对大产量粉煤灰混凝土同普通生产用的混凝土进行对比分析,得出结论:1)生产用混凝土的早期强度要好于大掺量粉煤灰混凝土的早期强度;2)小野田水泥大掺量粉煤灰混凝土早期强度要好于五岛水泥大掺量粉煤灰混凝土的早期强度;3)普通生产用混凝土28d之后的强度增长速度相对于大掺量粉煤灰混凝土的增长速度较慢.说明:粉煤灰对混凝土的后期强度增长起到了促进作用. 相似文献
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掺粉煤灰混凝土抗盐冻剥蚀性能研究 总被引:5,自引:0,他引:5
试验结果表明 :粉煤灰掺量为 2 0 %的混凝土在适量引气的条件下具有良好的抗盐冻性能 ;粉煤灰掺量为 5 5 %的混凝土在掺加UEA膨胀剂后其抗盐冻性能有明显改善 ;大掺量粉煤灰硫铝酸盐水泥混凝土的抗盐冻性大大低于同掺量的硅酸盐水泥混凝土 相似文献
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采用高效减水剂降低水胶比,配制具有良好性能的大掺量粉煤灰混凝土;研究养护温度对大掺量粉煤灰混凝土强度发展的影响.结果表明:养护温度对粉煤灰混凝土和纯水泥混凝土强度有不同的影响,较高的养护温度有利于大掺量粉煤灰混凝土强度的发展. 相似文献
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为了解决大体积混凝土开裂问题,采用一级粉煤灰,掺加高效缓凝保塑减水剂来配制混凝土,在改变粉煤灰掺量(0%,20%,30%,40%,50%)、水泥和粉煤灰总用量的条件下进行试验研究。通过混凝土绝热升温试验、掺粉煤灰水泥水化热试验和混凝土干缩性能试验,发现混凝土的抗裂性能随着粉煤灰掺量在一定范围内的上升而加强。如果将粉煤灰掺量控制在一定范围内,可以满足混凝土的抗裂性能,对大体积混凝土的应用提供了质量保证,防止了大体积混凝土的开裂产生。 相似文献
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This paper reports on a comprehensive study on the properties of concrete containing fly ash and steel fibers. Properties studied include unit weight and workability of fresh concrete, and compressive strength, flexural tensile strength, splitting tensile strength, elasticity modulus, sorptivity coefficient, drying shrinkage and freeze–thaw resistance of hardened concrete. Fly ash content used was 0%, 15% and 30% in mass basis, and fiber volume fraction was 0%, 0.25%, 0.5%, 1.0% and 1.5% in volume basis. The laboratory results showed that steel fiber addition, either into Portland cement concrete or fly ash concrete, improve the tensile strength properties, drying shrinkage and freeze–thaw resistance. However, it reduced workability and increase sorptivity coefficient. Although fly ash replacement reduce strength properties, it improves workability, reduces drying shrinkage and increases freeze–thaw resistance of steel fiber reinforced concrete. The performed experiments show that the behaviour of fly ash concrete is similar to that of Portland cement concrete when fly ash is added. 相似文献
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Low-calcium fly ash (FL) is a general product from the combustion of anthracite and bituminous coals and has been widely used as a mineral admixture to produce high strength and high performance concrete. Carbonation of cement blended with fly ash is much more complex than ordinary Portland cement because of the pozzolanic activity in an aluminosilicate glass phase of fly ash. In this paper, based on multi-component concept, a numerical model that can predict carbonation of low-calcium fly ash contained concrete was built. This numerical model includes two parts: hydration and carbonation models. The hydration model starts with a mix proportion of concrete and considers both Portland cement hydration and pozzolanic activity. By applying a hydration model, the amount of hydration product that is susceptible to carbonate as well as porosity was obtained as a function of curing age. Furthermore, the diffusivity of CO2 in concrete was determined and the carbonation depth of concrete was also predicted. The prediction results showed good agreement for the results of the experiment performed in this study. 相似文献
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利用粉煤灰开发高性能混凝土若干问题的探讨 总被引:8,自引:0,他引:8
现行规范对粉煤灰作为一般结构混凝土掺合料的品质和掺量有严格限制。通过实验研究和工程例证的分析表明:在低水胶比条件下,大掺量粉煤灰可明显改善大体积混凝土的性能,并可改善其温升-强度关系;在进行混凝土配合比设计时应将为煤灰作为独立组分考虑。提高粉煤灰利用水平,是发展绿色高性能混凝土的重要途径。 相似文献
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对掺量粉煤灰高性能混凝土和普通混凝土灌注桩进行抵抗硫酸盐和浓度镁盐的双重强侵蚀试验。试验表明掺量粉煤灰高性能混凝土,其可以抵抗硫酸盐和浓度镁盐的双重强侵蚀,完全能满足混凝土抗侵蚀要求。在相同配合比条件下,质量变化在腐蚀早期的质量变化率很接近,随着侵蚀龄期的增加,粉煤灰高性能混凝土抗侵蚀性能均优于普通水泥混凝土,这与耐蚀系数得出的结论基本上相吻合。 相似文献
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本文将中国西南地区某隧道弃渣中的火山岩破碎、粉磨制成磨细火山灰(GVA),通过扫描电镜(SEM)、X射线衍射(XRD)测试该火山灰的物理和化学性能,分析GVA对普通硅酸盐水泥水化、混凝土抗压强度及碳排放的影响。结果表明,GVA会延缓水泥水化进程,但延缓作用弱于同掺量粉煤灰(FA);GVA替代水泥50%(质量)时,混凝土28d抗压强度下降38.8%,掺入3%~5%硅灰(SF)可明显提高混凝土抗压强度;GVA替代水泥降低了混凝土碳排放指数(CI),建议掺量为20%。 相似文献
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Modeling of hydration kinetics in cement based materials considering the effects of curing temperature and applied pressure 总被引:1,自引:0,他引:1
Xiao-Yong WangHan-Seung Lee 《Construction and Building Materials》2012,28(1):1-13
Portland cement is the most widely used cement in the world. In the industrial by-products suitable for use as mineral admixtures in Portland concrete are ashes produced from the combustion of coal and granulated slag in metal industries. However, comparing such ashes with Portland cement, determining the hydration of this concrete is much more complex because of the reaction between calcium hydroxide and fly ash or slag. In this paper, the production of calcium hydroxide in cement hydration and its consumption in the reaction of mineral admixtures are considered in order to develop a numerical model for simulating the hydration of concrete, which contains fly ash or slag. The proposed numerical model includes the effects of water to binder ratios, slag or fly ash replacement ratios, curing temperature, and applied pressure. The heat evolution rate of fly ash- or slag-blended concrete is determined by the contribution of both cement hydration and the reaction of mineral admixtures. Furthermore, an adiabatic temperature rise in hardened blended concrete is evaluated based on the degree of hydration of the cement and mineral admixtures. The proposed model is verified through experimental data obtained from the concrete with different water-to-cement ratios and mineral admixture substitution ratios at elevated temperature and high pressure. 相似文献
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Performance Capacity of Concrete containing Fly Ash The conception to take into account the addition of fly ash to structural concrete presented in the German Standard DIN 1045‐2 should guarantee a high resistance of concrete structures against corrosive attack. In this context, criteria such as compressive and flexural strength of concrete, modulus of elasticity, bond strength, shrinkage and creep as well as the pore structure are focused in this paper. The obtained results on concretes containing a maximum of fly ash according to DIN 1045‐2 compared with concretes produced only with ordinary Portland cement show similar strength values at the age of 28 days while the strength development is somewhat lower for the fly ash concretes. However, at the age of one year the strength of fly ash concretes in particular also the flexural strength is considerably higher. Shrinkage and creep of the fly ash concrete is lower resulting in an overall reduced risk of shrinkage and thermal cracking. 相似文献