硅灰对硫铝酸盐水泥力学和电磁传输性能的影响

研究了硅灰掺量对硫铝酸盐水泥力学性能和电磁传输性能的影响.结果表明：随着硅灰掺量的增加,硫铝酸盐水泥的抗压强度和抗折强度均先增大后降低,硅灰的最优掺量为10%;硫铝酸盐水泥的电磁传输性能随着硅灰掺量的增加而增大,与未掺硅灰的样品相比,硅灰-硫铝酸盐水泥在3.94~5.99 GHz频段范围内电磁传输性能均有所提升,电磁透射率峰值最高提升了23.9%.     

硅灰对铝酸盐水泥胶合剂性能影响的试验研究

通过引入硅灰来改善铝酸盐水泥后期强度倒缩的问题,采取内掺的方式,研究了硅灰掺量对铝酸盐水泥胶合剂性能的影响.结果表明:适宜掺量下,硅灰能大大改善铝酸盐水泥的工作性能、力学性能和收缩性能,当内掺8％硅灰时,其早期抗压强度虽低于空白组,但28 d抗压强度接近空白组,达到123.6 MPa,且56 d抗压强度持续提高至127...     

硅灰对硫铝酸盐水泥水化行为的影响机理

通过抗压强度、凝结时间、电阻率测定以及X射线衍射(XRD)、扫描电镜(SEM)和孔溶液分析,研究了掺硅灰硫铝酸盐水泥浆体的水化行为.结果表明:5%掺量(质量分数,下同)的硅灰可以很好地改善水泥浆体的抗压强度,10%硅灰掺量的试样抗压强度只在1,28d时稍高于空白试样;掺入硅灰明显缩短了硫铝酸盐水泥的凝结时间;硫铝酸盐水泥的主要晶体水化产物是钙矾石,28d时的钙矾石量稍高于3d时,掺硅灰试样的钙矾石量要高于空白试样;掺硅灰试样的电阻率变化曲线高于空白试样,表明硅灰的掺入能够加快水泥的水化速率;硬化水泥浆体的孔溶液碱度随着硅灰掺量的增加而降低,掺硅灰试样的Ca2+浓度高于空白试样,表明硅灰促进了熟料的溶解,5%硅灰掺量试样的Al 3+浓度最低,表明其促进水化的效果更明显.     

不同掺量改性组分对硫铝酸盐灌浆水泥性能的影响

本文简要介绍了灌浆材料,主要针对目前遇到的问题和满足灌浆注浆的要求,分别以快硬硫铝酸盐水泥和硅酸盐水泥为基础,加入粉煤灰、硅灰、偏高岭土等改性优化组分,以及掺加少量减水剂和消泡剂设计不同的原料配比,配制出灌浆水泥。并对其物理力学性能、流动度和泛霜程度进行研究,通过试验结果得出了最优配料方案：水灰比0.7,硫铝酸盐水泥78%、硅灰掺量7%,偏高岭土掺量5%和粉煤灰10%。按此配比设计的硫铝酸盐水泥基灌浆材料流动性、强度和泛霜程度均满足要求。最优配比的硫铝酸盐水泥基灌浆材料的流动性能良好,7d、28d抗折强度和抗压强度满足要求、抗霜性能高。     

矿物掺合料对硫铝酸盐水泥基灌浆料性能的影响

为研究矿物掺合料对硫铝酸盐水泥基灌浆料力学性能及流动性能的影响,分别以硅灰、双飞粉、轻质碳酸钙为掺合料制备了硫铝酸盐水泥基灌浆料。在不同水胶比条件下,测试了灌浆料的流动度及不同龄期的抗折、抗压强度。试验结果表明:加入一定量硅灰可以提高灌浆料各龄期强度,但随着硅灰掺量增大,灌浆料流动度降低;加入一定量双飞粉对灌浆料流动度及各龄期强度均有负面影响;加入一定量轻质碳酸钙对灌浆料不同龄期抗压强度有所提高,对流动度及抗折强度没有明显影响。     

高强水泥基灌浆料配合比的正交试验研究

通过正交试验,研究了硫铝酸盐水泥、标准砂、硅灰、减水剂和膨胀剂掺量对水泥基灌浆料的流动度、3 d抗压强度和28 d抗压强度的影响。试验结果表明:硅灰掺量对灌浆料的流动度影响最大,减水剂掺量对水泥基灌浆料3 d抗压强度的影响最大,硅灰掺量对水泥基灌浆料28 d抗压强度的影响最大。通过正交试验分析优化得到高强水泥基灌浆料的配合比:硫铝酸盐水泥掺量为75%、标准砂掺量为40%、减水剂掺量为12%、硅灰掺量为2%、膨胀剂掺量为1.1%。     

矿物掺合料对铁铝酸盐水泥力学性能影响研究

针对铁铝酸盐水泥早期水化热高的问题,提出采用掺加矿物掺合料的方法改善铁铝酸盐水泥性能。研究了单独掺加不同掺量粉煤灰、矿粉、石灰石粉、粉煤灰微珠、硅灰的铁铝酸盐水泥用水量、力学性能,以及复合掺加粉煤灰-矿粉、粉煤灰微珠-矿粉、粉煤灰微珠-硅灰及石灰石灰石粉-矿粉的铁铝酸盐水泥用水量、力学性能。结果表明,粉煤灰等掺合料均会降低铁铝酸盐水泥强度,但是对用水量的影响不同,粉煤灰及硅灰会显著增加铁铝酸盐水泥用水量,石灰石粉及粉煤灰微珠会降低用水量。当掺合料单独掺加或复合掺加等量取代30%水泥时,复合胶凝体系的抗压强度降至45.0MPa左右,掺合料的掺量宜控制在30%以内。     

温度对桥梁伸缩缝快速修补材料体系性能影响研究

通过测试不同桥梁伸缩缝材料体系在不同温度下的凝结时间、抗压强度,结果表明硫铝酸盐胶凝材料体系凝结时间随温度降低而延长,在10℃～40℃时大致是线性关系,在-5℃～10℃时大致是指数关系。硫铝酸盐胶凝材料体系在低温条件下,掺加普硅、硅灰和碳酸锂有利于缩短凝结时间和前期抗压强度的提高,对后期抗压强度无不利影响,而聚合物的掺入会延长凝结时间和降低前后期的抗压强度。硫铝酸盐胶凝材料体系在高温条件下,掺加普硅、硅灰和碳酸锂会缩短凝结时间,对前期强度提高明显但会降低后期抗压强度;掺加聚合物后会延长凝结时间并提高后期抗压强度。     

矿物掺合料复掺对硫铝酸盐水泥防水砂浆性能的影响

本文主要研究了粉煤灰、矿粉和硅灰三种活性掺合料两两复掺对硫铝酸盐水泥砂浆抗折强度、抗压强度、吸水率及抗渗性能的影响,并通过扫描电镜观察了砂浆的微观形貌。研究结果表明,掺合料复掺会降低砂浆的早期强度,但对后期强度影响不大,明显降低了硫铝酸盐水泥防水砂浆的吸水率,当掺量达到1.5‰以上时,该种防水砂浆的7d抗渗压强能达到2.2MPa以上而仍未透水,远超普通水泥防水砂浆28d抗渗压强达1.5MPa的国标要求。     

硫铝酸盐水泥对无砂自流平材料物理力学性能的影响

研究了硫铝酸盐水泥(SAC)掺量对硅酸盐水泥基无砂自流平材料流动性和强度的影响,以及减水剂掺量和SAC掺量对硫铝酸盐水泥基无砂自流平材料流动性和强度的影响。结果表明:对于硅酸盐水泥基自流平材料,当SAC掺量由0增加到20%时,初始流动度基本保持稳定,30 min流动度持续降低,1d抗折强度和抗压强度先降低后有所提高,3、28 d抗折强度和抗压强度总体上不断降低;对于硫铝酸盐水泥基自流平材料,30 min流动度均为0,随着减水剂掺量从0.225%增加到0.300%,初始流动度先显著提高,后趋于稳定,抗折强度和抗压强度变化不大;当SAC掺量从200 g增加到280 g时,初始流动度有所增加,抗折强度和抗压强度显著提高。     

Compressive strength and stability of sustainable self-consolidating concrete containing fly ash,silica fume,and GGBS

This paper presents the findings of an experimental program seeking to understand the effect of mineral admixtures on fresh and hardened properties of sustainable self-consolidating concrete (SCC) mixes where up to 80% of Portland cement was replaced with fly ash, silica fume, or ground granulated blast furnace slag. Compressive strength of SCC mixes was measured after 3, 7, and 28 days of moist curing. It was concluded in this study that increasing the dosage of fly ash increases concrete flow but also decreases segregation resistance. In addition, for the water-to-cement ratio of 0.36 used in this study, it was observed that the compressive strength decreases compared to control mix after 28 days of curing when cement was partially replaced by 10%, 30%, and 40%of fly ash. However, a fly ash replacement ratio of 20% increased the compressive strength by a small margin compared to the control mix. Replacing cement with silica fume at 5%, 10%, 15%, and 20% was found to increase compressive strength of SCC mixes compared to the control mix. However, the highest 28 day compressive strength of 95.3 MPa occurred with SCC mixes in which 15% of the cement was replaced with silica fume.     

Influence of dry and wet curing conditions on compressive strength of silica fume concrete

This paper reports a part of an ongoing laboratory investigation in which the compressive strength of silica fume concrete is studied under dry and wet curing conditions. In the study, a total of 48 concretes, including control Portland cement concrete and silica fume concrete, were produced with four different water–cement ratios (0.3, 0.4, 0.5, 0.6), three different cement dosages (350, 400, 450 kg/m³) and three partial silica fume replacement ratios (10%, 15%, 20%). A hyperplastisizer was used in concrete at various quantities to provide and keep a constant workability. Three cubic samples produced from fresh concrete were demoulded after a day; then, they were cured at 20±2 °C with 65% relative humidity (RH), and three other cubic samples were cured at 20±2 °C with 100% RH until the samples were used for compressive strength measurement at 28 days. The comparison was made on the basis of compressive strength between silica fume concrete and control Portland cement concrete. Silica fume concretes were also compared among themselves. The comparisons showed that compressive strength of silica fume concrete cured at 65% RH was influenced more than that of Portland cement concrete. It was found that the compressive strength of silica fume concrete cured at 65% RH was, at average, 13% lower than that of silica fume concrete cured at 100% RH. The increase in the water–cementitious material ratios makes the concrete more sensitive to dry curing conditions. The influence of dry curing conditions on silica fume concrete was marked as the replacement ratio of silica fume increased.     

磷建筑石膏弹性模量和泊松比试验研究

通过对云南磷石膏进行改性制备成β型磷石膏,并掺入水泥、硅灰和减水剂制作了27个棱柱体试件,分别进行轴心抗压强度、弹性模量及泊松比试验。结果表明,掺量5%的硅灰对其强度的提高有一定的帮助;掺量0.5%的减水剂对其强度影响较大,轴心抗压强度标准值最高达到15.6MPA,最终得到的弹性模量参考值是1486N/mm~2,泊松比的参考值是0.12,同时由于磷建筑石膏高度脆性的性质,试件的主要破坏形态为劈裂状态。     

基于灰关联熵法的高性能混凝土强度影响因素分析

对于多种掺合料的高性能混凝土,找出诸多影响性能因素中的关键因素对配合比设计具有现实意义.通过强度试验,运用灰关联熵的系统分析方法,分析了胶水比、水泥强度、水泥掺量、磨细矿渣粉掺量、硅灰及膨胀剂掺量等因素对高性能混凝土28 d抗压强度性能影响的主次关系和影响程度.分析表明:对于高性能混凝土,胶水比始终是一个非常重要的参数,同时水泥的强度及其在胶凝材料中的掺量也是混凝土强度的重要保证;外加剂及矿物掺合料对混凝土强度的贡献则取决于外掺料本身的性能.结果证明:在高性能混凝土多因素的分析中,灰关联熵法是一种简单实用且结果比较准确的方法,研究结果可为高性能混凝土配合比设计参数提供有效的计算依据.     

硅灰和偶联剂对PB-g-PS胶乳改性水泥砂浆的性能影响

质量比为50/50的聚丁二烯接枝聚苯乙烯(PB-g-PS)胶乳用于改性水泥砂浆。考察了硅灰和偶联剂含量对胶乳改性水泥砂浆的流动度、抗压和抗折强度以及吸水量的影响。研究表明:改性砂浆的流动度随偶联剂含量的增加而增加,随硅灰的含量增加而降低;适量偶联剂和硅灰能降低改性砂浆的毛细孔吸水量;胶乳的加入使抗压强度降低,部分改性砂浆的抗折强度有所提高,偶联剂和硅灰的加入极大地改善了砂浆的力学性能,改性砂浆的抗压、抗折强度最大值分别为31.25、8.18 MPa。利用SEM观察了改性砂浆的结构,改性砂浆结构更加致密,界面结构得到改善,并观察到了带状和树枝状的聚合物膜结构。综上所述,硅灰、偶联剂和胶乳三者可以复合改性水泥砂浆。     

高活性偏高岭土微粉的制备及复合效应的研究

本文研究了高活性偏高岭土(MK)微粉的制备及与多种矿物掺料复合效应。以10％MK替代水泥，28d抗压强度提高约10MPa；以8％MK取代水泥配制高性能混凝土，其作用效果与硅灰相当，与矿渣基复合掺料复合(8％MK与35％复合矿渣替代水泥)掺入混凝土中，使混凝土物理、力学性能优干硅灰相同掺量的复合效果；与粉煤灰复合，可以使水泥标准稠度用水量降低，抗折、抗压强度提高，干缩率减少。     

Characteristics of lightweight concrete containing mineral admixtures

This research investigates the properties of fresh and hardened concretes containing locally available natural lightweight aggregates, and mineral admixtures. Test results indicated that replacing cement in the structural lightweight concrete developed, with 5–15% silica fume on weight basis, caused up to 57% and 14% increase in compressive strength and modulus of elasticity, respectively, compared to mixes without silica fume. But, adding up to 10% fly ash, as partial cement replacement by weight, to the same mixes, caused about 18% decrease in compressive strength, with no change in modulus of elasticity, compared to mixes without fly ash. Adding 10% or more of silica fume, and 5% or more fly ash to lightweight concrete mixes perform better, in terms of strength and stiffness, compared to individual mixes prepared using same contents of either silica fume or fly ash.     

矿物掺合料对C100～C120超高强混凝土基本性能的影响

通过正交试验考察了胶凝材料总量、水泥用量及超细粉煤灰用量对超高强混凝土抗压强度的影响,研究了硅灰、超细粉煤灰与复合硅材等矿物掺合料对C100~C120超高强混凝土基本性能的影响。结果表明,对超高强混凝土强度影响最主要的因素是水泥在胶凝材料中所占的比例;超细粉煤灰与硅灰复掺对超高强混凝土工作性能与强度改善效果较好;复合硅材对超高强混凝土的工作性能与强度均有一定的提高。