磨细粉煤灰对混凝土强度的影响

在阐明磨细粉煤灰比原状粉煤灰活性较高的理论基础上，论述了磨细粉煤灰对砼强度的效应，探讨了粉煤灰砼在冻融循环强度损失较大的原因。     

粉煤灰性质对混凝土流动度及强度的影响

本文通过高钙粉煤灰、低钙磨细粉煤灰和原状灰的不同掺量试验,对粉煤灰混凝土的流动性及早期和后期强度进行了研究,对于粉煤灰性质与混凝土流动性和强度之间的关系进行了初步分析和讨论。研究表明,粉煤灰的比重、需水量比和细度等物理性质对混凝土流动性有较大的影响;高钙粉煤灰混凝土比低钙粉煤灰混凝土的早期强度为高、有的高钙粉煤灰能提高混凝土早期强度。     

粉煤灰细度对水泥胶砂性能影响

研究不同细度的粉煤灰对水泥胶砂性能的影响，结果表明：需水量比与粉煤灰细度成一定线性关系；粉煤灰的掺入降低了水泥砂浆的早期强度，对后期强度有所增加，I级粉煤灰较II级粉煤灰对水泥砂浆后期强度的增长幅度较大。     

粉煤灰水泥土的强度特性试验研究

通过无侧限抗压强度试验探讨了水泥掺入比、粉煤灰掺入比、龄期这三个主要影响因素对粉煤灰水泥土力学性能的影响。试验结果表明,水泥土的强度随着水泥掺入比的增加而增加,考虑经济效益,水泥土中的水泥掺入比存在最佳掺入比,提出了最佳水泥掺入比为15%;水泥土中掺加粉煤灰能够使水泥土的后期强度得到大幅度的增强,但在一定程度上减小了早期强度;水泥土中也存在最佳粉煤灰掺入比,超过此掺入比粉煤灰水泥土的强度会减小,提出了最佳粉煤灰掺入比为8%;随着龄期的增长水泥土强度增长速率减缓,而粉煤灰可使水泥土后期强度增长速率有所加快。     

Ⅲ级粉煤灰代替细砂的试验研究

大掺量粉煤灰水泥砂浆的应用（粉煤灰代替细砂），是减轻燃煤废料污染、缓解天然砂缺少危机的有效途径。本文试验用Ⅲ级粉煤灰代替水泥砂浆中的细砂，比较了Ⅲ级粉煤灰品质、掺量，水胶比和胶凝材料总量对水泥砂浆抗压强度的影响，认为水胶比和粉煤灰掺量对水泥砂浆强度起主要作用，在低水胶比前提下，粉煤灰品质的影响不大。试验还进行了粉煤灰水泥砂浆的拓展度试验，试验结果表明：Ⅲ级粉煤灰掺胶比不掺胶的流动性好，按体积代替比按质量代替的流动性好。掺胶量对砂浆的流动性有影响。     

粉煤灰对混凝土抗冲磨性能的影响

研究了粉煤灰对混凝土强度和抗冲磨性能的影响,考虑了水胶比、粉煤灰掺量及引气剂等影响因素。结果表明:水胶比大于0.35的混凝土中掺入适量粉煤灰可以显著提高混凝土的抗压强度,但粉煤灰的掺入明显降低了混凝土抗冲磨强度。水胶比一定的情况下,粉煤灰掺量越大,混凝土抗冲磨强度越低。粉煤灰掺量一定时,混凝土的抗冲磨强度随水胶比的增加而降低。粉煤灰掺量对混凝土抗冲磨强度的影响大于水胶比。引气剂的掺入同时降低了混凝土的抗压强度和抗冲磨强度。     

粉煤灰对自密实混凝土性能影响的研究

研究了低水胶比下粉煤灰的掺量对自密实混凝土的流动性、稳定性、坍落度损失及强度的影响规律,根据试验结果,探讨了粉煤灰掺量对自密实混凝土工作性及强度的影响程度,并对粉煤灰的适宜掺量得出了有益的结论。     

大掺量低质粉煤灰配制中高强度混凝土试验研究

大量低品质粉煤灰在混凝土中的应用，是减轻燃煤废料污染、缓解矿物能源危机的有效途径。试验用较低品质粉煤灰配制中高强度混凝土，比较了粉煤灰品质、掺量，水胶比和胶凝材料总量对混凝土抗压强度的影响，认为水胶比和粉煤灰掺量对混凝土强度起主要作用。在低水胶比前提下。粉煤灰品质的影响不大。     

大掺量低质粉煤灰配制中高强度混凝土

大量低品质粉煤灰在混凝土中的应用，是减轻燃煤废料污染、缓解矿物能源危机的有效途径。本文试验用较低品质粉煤灰配制中高强度混凝土，比较了粉煤灰品质、掺量，水胶比和胶凝材料总量对混凝土抗压强度的影响。认为水胶比和粉煤灰掺量对混凝土强度起主要作用，在低水胶比前提下，粉煤灰品质的影响不大。     

矿物掺合料对结构轻集料混凝土强度的影响

提出了混凝土实现高性能化的基本技术途径,着重研究了粉煤灰、矿渣、硅灰的单掺对轻集料混凝土强度的影响,得出了硅灰对轻集料混凝土强度的贡献比矿渣和粉煤灰的大,并对硅灰的作用机理进行了探讨,以促进高性能混凝土的研究。     

引气粉煤灰混凝土抗冻融耐久性的研究

通过试验研究,探讨了强度等级、引气量水平、水灰比等因素对普通混凝土和粉煤灰混凝土抗冻融耐久性的影响．研究指出,混凝土的引气量和强度是影响普通混凝土和粉煤灰混凝土抗冻性的决定因素．满足抗冻性要求的引气量取决于相应的混凝土强度等级．美国标准ＡＣＩ３１８—８３ 中对抗冻混凝土最小引气量、最大水灰比的限制,以及鲍尔氏（Ｐｏｗ ｅｒｓ）推荐的气泡间距指数（０．２５ ｍ ｍ ）都过于保守．给出了相应参数的推荐数值．     

粉煤灰混凝土的抗冻融耐久性

通过试验研究，探讨了强度等级，引气量，粉煤灰品质等因素对普通混凝土和粉煤灰混凝土抗冻融耐久性的影响，结果表明，混凝土的引气量和影响普通混凝土和粉煤灰混凝土抗冻性的决定因素，满足抗冻性要求的引气量取决于相应的混凝土强度等级。本文还推荐了抗冻混凝土最小引气量，最大水灰比的限制值，以及气泡间距指数这一参数值。     

正交设计选择粉煤灰再生混凝土最佳配合比

研究了再生骨料掺量、粉煤灰取代水泥量、粉煤灰超量系数和水灰比对粉煤灰再生混凝土抗压强度的影响。正交试验表明 ,水灰比是影响粉煤灰再生混凝土强度的主要因素 ,再生骨料掺量是次要因素 ;通过正交分析 ,提出了粉煤灰再生混凝土的最佳配合比     

粉煤灰对水泥浆体自收缩和抗压强度的影响

设计组装了水泥浆体自收缩测量装置,进行了不同粉煤灰掺量和水胶比的水泥浆体自收缩和抗压强度测试,采用压汞测孔仪(MIP)、扫描电镜(SEM)等测试技术研究了粉煤灰对水泥浆体孔结构、产物形貌等微观结构的影响,并对其影响机理进行了分析.结果表明:粉煤灰能够有效抑制水泥浆体的早期自收缩,在7d前,其自收缩随着粉煤灰掺量的增加而...     

线性回归分析对粉煤灰再生混凝土强度的预测

通过正交试验设计,采用粉煤灰代砂法掺入再生混凝土,并进行配合比设计。研究各材料用量与混凝土抗压强度之间的关系,利用线性回归分析推导出各材料用量与粉煤灰再生混凝土28d强度之间的定量关系。试验结果表明,线性回归分析显著,具有参考价值。     

Potential use of spent mushroom compost ash as an activator for pulverised fuel ash

The utilization of pulverised fuel ash (PFA) as a replacement material for Portland cement has resulted in improved concrete properties. However, the pozzolanic activity of PFA is slow, resulting in poor strength development of PFA concrete at early ages. To overcome this problem many researchers have investigated methods of activating (mechanically, thermally and chemically) the pozzolanic reactivity of PFA. This paper assesses the potential use of spent mushroom compost ash (SMCA) as a chemical activator for PFA blended cement systems.When added to the PFA/OPC paste mix SMCA had the effect of improving early strength development. X-ray diffraction results showed that, in the mix which contained 20% SMCA, ettringite formation was improved at both 7 and 28 days, whereas thermogravimetric analysis identified depletion of calcium hydroxide levels at both 3 and 7 days for the same sample pastes. It is therefore considered that the increased strength development in SMCA mixes is a result of the presence of large quantities of sulfates in SMCA, which, when hydrated, has activated the glassy phases present in PFA to form ettringite, as well as possibly accelerating the pozzolanic activity.     

The effect of high temperature curing on the strength and carbonation of pozzolanic structural lightweight concretes

An experimental study on the compressive strength and carbonation depth of lightweight concrete mixes that contain pulverized fuel ash (PFA) and silica fume (SF) as cement replacements is presented in this paper. Mixes that had a relatively high replacement level of PFA at 25, 40, and 55% and of SF at 5, 10, and 15% by weight were compared. The results indicated that accelerated curing at 60 °C for 3 days improved the 28-day compressive strength of the PFA- and SF-incorporated mixes but resulted in higher carbonation of the mixes compared with that under normal temperature curing. Mixes that had 25% PFA or 5–10% SF as partial cement replacements had slightly higher strength under accelerated curing and slightly lower strength under normal curing than the control mix. At higher replacement levels of PFA and SF, further lower strength and higher carbonation was observed.     

超细粉煤灰在混凝土中的应用

通过对超细粉煤灰（SPFA）和常规粉煤灰（PFA）减水性能的对比试验，发现SPFA具有良好的减水性能，并通过大量的掺加SPFA和PFA的混凝土试验配合比得到证实。对混凝土抗压强度发展趋势的分析表明SPFA作为水泥替代材料具有良好的胶凝性能，可将其应用于高强高性能混凝土中。     

水泥黄土的工程特性探讨

主要探讨了水泥黄土的工程性质与掺合比的关系,以及含水量对强度的影响问题,通过试验表明:水泥黄土的最优含水量随着水泥掺入量的增大而增大;最大干密度随着水泥掺入量的增大而减小,但是变化量均较小,水泥黄土强度随着龄期的增长而增大,在前期含水量对强度的影响不大,但在后期含水量越接近水泥黄土的最优含水量其强度越大,从总体上来说强度的增长是越来越慢的。     

An assessment of cement-PFA and lime-PFA used to stabilize clay-size materials

Difficulties in construction operations are often associated with clay soils. However, the engineering behaviour of such soils can be improved by stabilizing them with the addition of small amounts of cementitious materials. Nonetheless because clay soils possess a range of mineralogical compositions some are more easy to estabilize than others. In order to investigate this problem, three of the principal components found in clays, namely, kaolinite, montmorillonite and quartz, were chosen. These three components were treated with varying amounts of cement plus PFA. and lime plus PFA. PFA was used as an extender with cement and with lime to evaluate how effective such mixtures are when used to stabilize clay soils. The addition of PFA reduces the cost of the stabilizing agent. Because stabilization of clay soils most frequently has been used in connection with road construction, kaolinite, montmorillonite and quartz were subjected to the types of test used in the design procedure for roadways, that is, consistency limit tests, compaction tests, California bearing ratio tests, unconfined compressive tests, and tests to determine Young's modulus. Except for those samples used for assessment of consistency limits, the others were prepared with optimum values of moisture content and maximum dry density. Those samples used for unconfined compression and modulus of elasticity measurements were cured for different periods of time. The results of the various tests were examined to see if there was an optimum amount for a particular addition which would bring about maximum enhancement of engineering performance of the components concerned. Generally mixtures of cement and PFA or lime and PFA did not give as good results as when cement and lime were used on their own. Also those mixtures with the highest proportions of cement and of lime usually gave the better improvement in values. Nevertheless it may be worth making some sacrifice in soil improvement to obtain the saving in cost that the use of PFA brings.