硅灰与氧化石墨烯对硬化水泥浆体的复合增强效应

研究了硅灰与氧化石墨烯复掺时对硬化水泥浆体力学性能的影响. 分别进行了普通水泥浆体、内掺质量分数10%的硅灰水泥、外掺质量分数0.8%的氧化石墨烯复合聚羧酸减水剂（GOPCs）水泥浆体以及同时内掺硅灰与外掺GOPCs的水泥浆体的配制. 对4种硬化水泥浆体的抗折强度、抗压强度以及90 d龄期孔隙率进行了测定,同时采用X射线衍射仪及扫描电子显微镜对水泥水化产物进行分析,并将4种样品的力学性能进行比较. 结果表明,当掺10%硅灰时,硬化水泥浆体90 d抗压强度比空白样提高了3.6%,抗折强度提高了9.6%;当只使用氧化石墨烯复合聚羧酸减水剂而不掺硅灰时,抗压强度提高了11.9%,抗折强度提高了15.3%;当硅灰与氧化石墨烯复掺时,抗压强度提高了22.7%,抗折强度提高了38.6%. 孔隙率的变化以及XRD、SEM分析证实了这一结果. 因此,硅灰与氧化石墨烯复合聚羧酸减水剂对硬化水泥浆体具有复合增强作用.     

水泥基材料隐身性能改性试验与数值模拟

以水泥为基体,添加硅灰和粉煤灰、石墨和碳纤维、纳米TiO2和钢纤维为吸波剂的试样,对8～18GHz频段内的隐身性能进行了试验分析,结果表明,硅灰和粉煤灰、纳米TiO2和钢纤维与水泥复合制成的吸波材料具有良好的隐身性能,石墨和碳纤维与水泥复合制成的吸波材料的隐身性较差,掺合材对水泥基材料吸波性能的影响必须综合考虑,并不是越多越好,掺合材超过一定极限后,材料的透波能力增强,吸波性能便会下降.在设计时对试件实验数据进行计算机模拟仿真,得到水泥基复合吸波材料,材料的电导率、复介电常数、复磁导率、介质损耗角正切等是评价吸波材料的主要参数.当掺合材作为复合吸波剂应用时,两种材料的介电损耗共同发挥衰减作用,可以明显提高试件的吸波性能,而且可以拓宽频段,比单一吸波剂的添加有着明显的优势.     

120MPa超高强水泥基材料的研究

采用常规原材料，普通成型工艺，通过正交设计试验研究，配制出了抗压强度为120MPa的超高强水泥基材料，并给出了优选配比。超高强水泥基材料的杭压强度和抗折强度试验的极差方差分析结果表明：水胶比为影响超高强水泥基材料强度的最显著因素，超细掺合料硅灰的掺量和减水剂的掺量也有一定的影响。     

早强剂对掺硅灰的水泥砂浆强度与结构影响的研究

探讨了不同早强剂对掺硅灰的水泥砂浆强度及微观结构的影响.结果表明：掺入不同的早强剂均可提高掺硅灰的水泥砂浆早期强度,且对其1 d抗压强度的增强效果优于3 d.其中掺入适量的硫酸钠可迅速生成大量的钙矾石晶体,提高水泥砂浆的密实度,同时促进了硅灰的火山灰反应,明显提高了掺硅灰的水泥砂浆的早期强度,但早强剂对掺硅灰的水泥砂浆后期强度影响不大.3种早强剂对掺硅灰的水泥砂浆早期强度增强作用从大到小的顺序依次为硫酸钠、氯化钙、三乙醇胺,其中硫酸钠掺量为3%时增强作用最佳.     

The Accelerated Test of Chloride Permeability of Concrete

1　IntroductionConcretenormallyprovidesagoodprotectionagainstcorrosionofreinforcementbecauseofthehigheralkalineofporesolutionandtheformationofpassivelayeronthesurfaceofsteel .Inasalineenvironment,however,thepassivelayercanbedestroyedbytheintrusionofchlorideionstoathresholdvalue[1] andthecorrosionofsteelmayoccur.Thepenetrationofchlorideionsintoconcreteismainlythroughdiffusion .Determinationofchlorideperme abilityofconcretebynaturaldiffusionistimeconsump tive .Inasalineenvironmenthoweverwhereco…     

Reaction degree of silica fume and its effect on compressive strength of cement-silica fume blends

The compressive strength of the cement-silica fume blends with 5mass%, 10mass%, 20mass% and 30mass% of silica fume and water to binder ratio of 0.28, 0.32 and 0.36 from three days to ninety days were investigated. The reaction degree of silica fume was calculated from the Q4 silica tetrahedron, which was used as a probe obtained from 29 Si solid state nuclear magnetic resonance analysis. The fl at of compressive strength after 28 days disappeared for blended cement with inereasing reaction degree of silica fume. The compressive strength of the blended cement pastes approached that of P.I. cement pastes after 56 days and exceeded that after 90 days. The addition of silica fume and the w/b ratio of blends are both critical to the reaction degree of silica fume. The appropriate addition of silica fume, high silica fume reaction degree and low w/b ratio are benefi cial to the compressive strength of the cement-silica fume blends.     

微硅粉和聚丙烯纤维对混凝土抗裂性研究

为使混凝土具有良好的耐久性,必须先解决混凝土的抗裂性.因此,在混凝土原材料中加入聚丙烯纤维、微硅粉、矿渣来优化混凝土的抗裂性.用试验手段和正交设计来分析不同掺量时聚丙烯纤维、微硅粉以及矿渣对混凝土抗裂性能的影响.试验结果显示:聚丙烯纤维对混凝土的性能影响尤为显著;掺入微硅粉有利于增强混凝土的抗压强度和抗抗劈裂强度;复合...     

Ultra high early strength self-compacting mortar based on sulfoaluminate cement and silica fume

The influences of silica fume and aluminum sulfate on hydration process of sulfoaluminate cement were carried out by ring flow, setting time, hydration heat, XRD and DTG analyses. In addition, mortar mixtures with different functional additives have been studied through compressive strength, flexural strength, volume stability at early age and porosity characterization tests. The results show that the addition of silica fume and aluminum sulfate reduces the fluidity and shortens the setting time of sulfoaluminate cement paste, promoting hydration process and increasing hydration products at early age. In the case of appropriate proportion of mortar, the inclusion of hydroxy propyl methyl cellulose, dispersible polypropylene fiber and organic silicon kind of defoamer can control segregation and bleeding, improve mechanical strength and volume stability at early age, and modify the pore distribution of sulfoaluminate cement mortar, respectively. The sulfoaluminate cement mortar can carry out gravitational grouting in the absence of outside force, the compressive strength of 2 hours and 24 hours have reached 26 and 58 MPa respectively, and have good microexpansion and tiny pore distribution characterization.     

纳米硅粉水泥土固化机理研究

将具有优异性能的纳米硅粉作为外掺剂应用于水泥土改性研究.通过室内无侧限抗压强度试验,探讨了纳米硅粉掺人比和龄期对水泥土强度的影响规律;结合水泥石强度试验和X射线衍射(XRD)试验,研究了纳米硅粉对水泥浆的改性效果和改性机理;通过扫描电镜(SEM)测试,分析了纳米硅粉水泥土的微结构特点及微结构形成过程;在纳米硅粉-土相互作用分析的基础上,提出了纳米硅粉水泥土的固化机理,该研究将为纳米硅粉在水泥土中的进一步应用奠定理论和试验基础.     

绿色与智能建筑初探

绿色智能建筑就是运用现代高科技手段,达到节约能源资源、保护环境,以人为本为目的的新型绿色建筑.它是一种用现代科学技术武装起来的绿色建筑,是把环保技术、节能技术、信息技术、网络技术渗透到建筑且使用于住户生活的各个方面,用最新的理念、最先进的技术去解决生态健康和居住舒适度的问题,解决可持续发展问题.笔者着重阐述了绿色建筑和智能建筑的概念及绿色建筑与建筑智能的关系。     

玄武岩纤维喷射混凝土在热害环境下的性能试验研究

以隧道热害问题为背景,通过模型试验、近似模拟湿喷技术、定量分析及微观测试相结合的方法研究不同掺量玄武岩纤维喷射混凝土劈裂强度和粘结强度等力学性能的影响,横向对比标准养护和干热养护下的不同体积掺量的玄武岩纤维混凝土的力学性能,同时也加入硅灰以及钢钎维作为参照,以便从机理程度上提出更有效的解决热害措施。试验研究表明:在混凝土中加入玄武岩纤维,对混凝土起到了增强和阻裂的作用,改善了混凝土的脆性易裂的破坏状况。干热环境下,加入少量的玄武岩纤维能够提高混凝土的力学性能。当玄武岩掺量为0.1%玄+5%硅灰时,喷射混凝土的力学性能最好,加入0.2%玄武岩纤维掺量,也有一定程度的改善。实际隧道施工中,可通过加入适量的玄武岩纤维和适量的硅灰,可降低混凝土在热害环境下的危害。     

Analysis of the Damping Behavior and Microstructure of Cement Matrix with Silane-treated Silica Fume

The surface treatment of silca fume with silane coupling agent prior w incorporation in a cement mortar resulted in composites exhibiting increuses in loss tangent by 5%-200% and storage modulus by 10%-20% , relative to the value obtained by using as-received silica fume. The scanning electron microscopy （SEM） images iindicate that there is a morphological difference in the cement paste with treated and as-received silica fume, The, X-ray diffraction （XRD）, infrared （IR） spectrum analyses and mercury intrusion porosimetry （ MIP ） have provided evidence to understand the reaction mechanism between treated silica .fume and the hydrate product of cement. This has led to the establishment of an initial microscopic model describing the damping behavior of cement matrix.     

Influence of fly ash and silica fume on water-resistant property of magnesium oxychloride cement

By incorporation of fly ash or silica fume into magnesium oxychloride (MOC) cement, a high water resistance material can be formed for successful industrial applications. The influences of fly ash and silica fume on water-resistant property were investigated by SEM and EDS. It is found that the incorporation of fly ash or silica fume can improve the water-resistance of the MOC. The improvement of the water resistance of the MOC incorporated with fly ash or silica fume may be attributed to the alumino-silicate 5·1·8 gel or silicate 5·1·8 gel.     

多元复合超早强灌浆料试验

目的研究铝酸盐水泥、普通硅酸盐水泥、石膏和硅灰四元复合体系超早强灌浆料的流动度、凝结时间和力学性能,找出超早强灌浆料的最佳配比．方法采用行星式搅拌机将原材料搅拌均匀,利用跳桌测试流动度,贯入阻力法测定凝结时间,水泥压力试验机测试力学强度,混凝土收缩膨胀仪测试膨胀性能,分析砂胶比为1．0的微观结构．结果该体系辅以多种外加剂,采用高胶砂比可以保证初始流动度大于325mm,30min流动度大于280mm,2h抗压强度达34．80MPa,24h抗折达13．82MPa,28d抗压强度大于99．90MPa,56d抗压强度大于28d抗压强度．早期SEM微观结构显示晶形生长良好,结构致密．结论铝酸盐水泥、普通硅酸盐水泥、石膏和硅灰按一定的比例复配,具有良好的施工和易性和力学性能．     

硅灰粉煤灰对喷射混凝土性能影响

为了解决现场喷射混凝土普遍存在强度低、喷层易开裂、回弹量大、粉尘浓度高等问题,在喷射混凝土中加入不同掺量的硅灰、粉煤灰替代水泥,并通过室内试验和现场试验研究硅灰、粉煤灰对添加铝酸盐液态速凝剂喷射混凝土性能的影响。结果表明:铝酸盐液态速凝剂掺量为3%时,凝结效果最好;单掺8%的硅灰能有效促进铝酸盐液态速凝剂的凝结效果,提高混凝土强度,增加粘聚性;单掺粉煤灰可以降低速凝剂的促凝效果、降低混凝土强度、提高和易性。硅灰、粉煤灰和铝酸盐液态速凝剂混掺,对混凝土1 d抗压强度影响由主到次为粉煤灰掺量>速凝剂掺量>硅灰掺量,28 d抗压强度影响由主到次为速凝剂掺量>硅灰掺量>粉煤灰掺量,从而得出三者最佳组合。并结合新型喷射工艺进行现场试验,得出最佳组合能有效减少水泥用量、提高喷射混凝土强度、减少开裂、降低回弹和粉尘的结论。     

油井水泥腐蚀的能谱分析研究

水泥石在含有不同离子成份的腐蚀液中浸泡，用能谱仪测定了腐蚀后水泥石中各元素的含量。发现，氯离子、硫酸根离子能渗入到水泥石内部深处；在水泥浆中加入硅灰，这种作用明显减弱；在上述两种水泥石内部，镁离子的含量均无明显变化。指出，硫酸根离子在水泥石内的扩散不完全是物理扩散，也有化学扩散；要防止硫酸根离子的侵蚀，改变水泥水化产物的组成是关键；要防止镁离子的侵蚀，水泥石不应有缺陷。     

硅灰钢纤维对混凝土性能影响的试验研究

为使混凝土具有良好的抗裂性能,在混凝土原材料中加入钢纤维、硅灰、矿渣来改善混凝土的抗裂性.用正交设计和理论分析研究不同掺量的钢纤维、硅灰、矿渣对混凝土抗裂性能的影响.试验结果表明：钢纤维对混凝土的性能影响尤为显著;掺入硅灰有利于增强混凝土的抗压强度和劈拉强度;复合使用钢纤维、硅灰、矿渣能明显改善高性能混凝土的后期强度;钢纤维、硅灰、矿渣在混凝土中的最佳掺量是10%,7%,7%。     

低温硅灰-硅酸盐水泥复合胶凝体系力学性能及微观结构

目的研究不同温度体系时不同的硅灰掺量对复合胶凝体系的力学性能及微观结构的影响．方法在低温条件下,将体积分数为0、2％、5％、8％、10％的硅灰掺入到硅酸盐水泥中,测试水泥砂浆的抗压、抗折强度,进行SEM扫描电镜分析．结果随着硅灰掺入量的增加,复合胶凝体系的力学性能呈现先增加后降低的趋势,结构趋于密实;当硅灰的掺量达到8％时,复合胶凝体系的14d抗压、抗折强度达到最大值．结论低温环境影响了复合胶凝体系力学性能的发展,硅灰的加入促进了复合胶凝体系的水化,改善了水泥石的微观结构．     

硅灰对水泥净浆抗硫酸盐侵蚀性能的改善作用

将水泥净浆试件在5%Na2SO4溶液中长期浸泡,用试件强度随浸泡时间的变化和试件中物相的XRD分析,研究了硅灰对水泥净浆抗硫酸盐侵蚀性能的影响.在Na2SO4溶液侵蚀下,普通硅酸盐水泥净浆试件强度随浸泡时间先增长,然后急剧降低;外观和XRD相分析表明,其原因是由于形成了膨胀性钙矾石,造成试件开裂破坏;加入硅灰的水泥净浆试件强度损失明显减小,尤其是抗折强度没有降低,其抵抗强度下降系数还略有增加;原因是由于硅灰的稀释作用和火山灰效应减少了水泥净浆中Ca(OH)2的量,从而降低了水泥净浆试件在硫酸盐溶液侵蚀下形成的膨胀性钙矾石的量.因而,硅灰对水泥混凝土抗硫酸盐侵蚀性能有改善作用.     

Effect of Fly Ash and Silica Fume on Hydration Rate of Cement Pastes and Strength of Mortars

The effect of fly ash and silica fume on hydration rate and strength of cement in the early stage was studied. Contrast test was applied to the complex cementitious system to investigate the hydration rate. Combined with mechanical strength, the influence of fly ash and silica fume during the hydration process of complex binder was researched. The peak of the rate of hydration heat evolution and the mechanical strength decreased as the ratio of fly ash increased, however, as the ratio of silica fume increased, the peak of the rate of hydration heat evolution and the mechanical strength increased obviously. When the ratios of fly ash and silica fume are 10% and 5%, the peak of the rate of hydration heat evolution is the highest. At the same time 7 days of flexural and compressive strength are the highest as 8.89 MPa and 46.52 MPa, respectively. Fly ash and silica fume are the main factors affecting the hydration rate and the mechanical property.