Effect of silica fume and glass powder for enhanced impact resistance in GGBFS-based ultra high-performance geopolymer fibrous concrete:An experimental and statistical analysis

Solid waste recycling is an economically sound strategy for preserving the environment,safeguarding natural resources,and diminishing the reliance on raw material consumption.Geopolymer technology offers a significant advantage by enabling the reuse and recycling of diverse materials.This research assesses how including silica fume and glass powder enhances the impact resistance of ultra-high-performance geopolymer concrete(UHPGC).In total,18 distinct mixtures were formulated by substituting ground granulated blast furnace slag with varying proportions of silica fume and glass powder,ranging from 10%to 40%.Similarly,for each of the mixtures above,steel fibre was added at a dosage of 1.5%to address the inherent brittleness of UHPGC.The mixtures were activated by combining sodium hydroxide and sodium silicate solution to generate geopolymer binders.The specimens were subjected to drop-weight impact testing,wherein an examination was carried out to evaluate various parameters,including flowability,density at fresh and hardened state,compressive strength,impact numbers indicative of cracking and failure occurrences,ductility index,and analysis of failure modes.Additionally,the variations in the impact test outcomes were analyzed using the Weibull distribution,and the findings corresponding to survival probability were offered.Furthermore,the microstructure of UHPGC was scrutinized through scanning electron microscopy.Findings reveal that the specimens incorporating glass powder exhibited lower cracking impact number values than those utilizing silica fume,with reductions ranging from 18.63%to 34.31%.Similarly,failure impact number values decreased from 8.26%to 28.46%across glass powder contents.The maximum compressive and impact strength was recorded in UHPGC,comprising 10%silica fume with fibres.

Influence of Silica Fume on Corrosion Behaviour of Reinforced Steel in Different Media

Electrochemical and corrosion behaviour of reinforced steel embedded in cement pastes incorporating different amounts of silica fume as a partial replacement of cement has been studied in chloride and sulphate solutions by using different electrochemical techniques. The results indicate that, while steel passivity degree is low in the control samples' upon soaking in the corrosive media, it has been high in samples incorporating silica fume and increased with increasing silica fume content. The improvement effect of silica fume may be attributed to the pore solution structure of the cement paste, which limits the mobility of aggressive ions near the surface of the steel. The mechanism of steel corrosion due to chloride and sulphate attack and passivation effect of silica fume are discussed.

钢渣粉与硅灰复掺水泥基材料的流变、早期水化热与强度

为缓解大量存在且利用率很低的钢渣处理难题,将其研磨成微粉置换水泥,并掺入硅灰形成一种兼顾力学性能、绿色低碳水泥基材料。基于不同配比的复掺水泥基材料体系的流变行为、早期水化热、强度与吸水率试验研究,主要结果如下:钢渣粉颗粒微形貌棱角与片状较少,替代15%水泥时可有效改善基体稠度,略微降低强度,并显著降低早期水化放热(降幅8.8%),有利于控制早期温度裂缝。复掺硅灰可有效降低材料塑性黏度与泵送压力,对需要长距离泵送的大体积混凝土或高性能混凝土,硅灰掺量可控制在5%以内。且硅灰空间填充效应与火山灰反应会增强材料密实性,显著提高强度。综上,复掺15%钢渣粉和5%硅灰的水泥基材料,不仅可以改善泵送性能,提升强度和耐久性,还能降低早期水化放热量,具有良好的工程应用前景。

基于核磁共振技术的硅灰纤维浮石混凝土分形特征与强度关系分析

为探究硅灰与玻璃纤维对浮石混凝土的协同效应,用硅灰等质量取代水泥制备玻璃纤维浮石混凝土(GFRPC)并对其进行宏观力学试验。借助核磁共振技术(NMR)对GFRPC孔隙结构进行测试,并结合分形理论定量描述孔隙结构复杂程度,探讨孔隙特征参数、分形维数与抗压强度之间的关系。结果表明:硅灰与玻璃纤维的协同效应能有效提高GFRPC力学性能,与抗压强度相比,劈裂抗拉强度与韧性性能提高更为显著;GFRPC核磁共振T2谱呈“主次峰”结构,其孔隙结构具有明显多重分形特征,不同孔径范围孔隙分形维数及特征存在显著差异;添加硅灰能有效改善水泥基体与玻璃纤维、浮石骨料间界面过渡区的结构组成,增强其界面黏结性能。综合考虑孔隙特征参数和分形维数两方面因素对GFRPC抗压强度的影响,在此基础上建立的强度-孔隙结构模型拟合精度较高,模型预测值与试验值的平均相对误差为1.047%。

钢渣基三元混凝土的制备及性能研究

为了促进钢渣的资源化利用,解决钢渣因活性低而导致实际应用受阻的问题,本文以钢渣、偏高岭土和硅灰为掺合料,设计L_(9)(3^(3))正交表并制备胶砂试件,研究掺合料配比、总掺量和钢渣细度三个因素对胶砂试件力学性能的影响,筛选出最优的水平因素组合,并在此基础上制备钢渣基三元混凝土,对最优水平因素组合进行优化验证。结果表明:胶砂试件受掺合料总掺量的影响最大,最优水平因素组合为掺合料配合比1∶2∶2(硅灰∶钢渣∶偏高岭土),总掺量20%,钢渣细度D_(90)为147μm;同时,以最优水平因素组合设计的钢渣基三元混凝土,与钢渣单掺混凝土相比,3 d抗压强度提升了31.71%,7 d抗压强度提升了54.21%,28 d抗压强度提升了9.84%;与标准水泥混凝土相比,3 d抗压强度提升了4.68%,7 d抗压强度提升了15.88%,28 d抗压强度提升了5.71%,满足钢渣作为掺合料实际应用到混凝土中对强度的要求。

硅灰-聚丙烯纤维双掺混凝土的动静态力学性能

为了研究硅灰取代率和聚丙烯纤维掺量对混凝土力学性能的影响,采用WAW-1000型微机控制电液伺服万能试验机和分离式Hopkinson压杆(SHPB)进行试验,分析混凝土试件的动静态抗压强度、材料韧性、能量变化和破碎块度,得到不同配合比下的硅灰-聚丙烯纤维双掺混凝土力学性能。结果表明:随硅灰取代率(0%~9%,质量分数)的增加,双掺混凝土的动静态抗压强度和韧性先上升后下降;随聚丙烯纤维掺量(0~4 kg·m^(-3))的增加,动静态抗压强度和韧性缓慢增长。掺入硅灰和聚丙烯纤维有利于提高混凝土的耗能效果和破碎块度质量比,透射能和破碎块度质量比随硅灰取代率的增加先增大后减小,随聚丙烯纤维掺量的增加而增大。硅灰加强了砂浆-粗骨料的界面结合,杂乱分布的聚丙烯纤维约束了裂纹的发展,两者的共同作用显著提高了混凝土的动静态抗压强度、韧性、抗冲击能力和抵抗破坏的能力。

聚丙烯纤维和硅灰对轻骨料混凝土性能的影响

研究了聚丙烯纤维(PF)掺量(0、0.2、0.4、0.6、0.8、1.0、1.2 kg/m^(3))与硅灰掺量(0、1%、2%、3%、4%、5%、6%、7%、8%)对轻骨料混凝土(LAC)抗压、抗折强度和抗冻性能的影响。结果表明:同时掺入适量的PF和硅灰有效提高了LAC的抗压、抗折强度,其中,对于抗压强度,最佳PF和硅灰的掺量分别为0.8 kg/m^(3)和5%;对于抗折强度,最佳PF和硅灰的掺量分别为1.0 kg/m^(3)和5%;当PF和硅灰的掺量分别为1.0 kg/m^(3)和5%时,LAC试件的抗冻性能相对最优。

机制砂、硅灰和钢纤维制备改性混凝土性能研究

采用机制砂100%替代天然河砂,制备机制砂、硅灰和钢纤维改性混凝土。共设计制作13组混凝土试件,硅灰添加量为胶凝材料总质量的0%,7.5%,15%,钢纤维添加量为混合料总体积的0%,0.5%,1%,1.5%。通过开展抗压强度、劈裂抗拉强度、抗弯强度和抗冲击强度测试,研究改性混凝土工作性能和力学性能。研究结果表明,与使用天然河砂制备的混凝土相比,使用机制砂制备的混凝土力学性能在一定程度上有所提高。与未添加硅灰和钢纤维的混凝土相比,添加硅灰的混凝土抗拉强度显著提高,添加钢纤维的混凝土抗拉强度和抗冲击强度显著提高。

钢管微膨胀混凝土的制备及其性能研究

钢管和混凝土两种材料的收缩性能不同,容易导致接触面脱离。掺加膨胀剂能够较好的抑制钢管和混凝土的脱离,但需要借助高吸水性树脂等内养护剂为膨胀剂的水化过程补给水分。本文以膨胀剂、高吸水树脂、硅灰的掺量为变量设计L9(33)正交试验,试验各组配合比下混凝土的力学性能和耐久性能,并采用功效函数法进行评估决策,结合主观赋权法和客观赋权法进行权重分配,计算并比较各方案的综合效益值,选择综合效益值最高的方案作为最优配合比。经筛选,最佳配合比(第H5组)的掺量组合为膨胀剂10%、高吸水树脂0.3%、硅灰6%。

MECHANICAL BEHAVIOUR AND INTERFACIAL PERFORMANCE OF STEEL FIBER REINFORCED SILICA FUME HIGHSTRENGTH CONCRETE

In this paper, the flexural, split tensile, impact and fatigue performance of steel fiberreinforced silica fume high-strength concrete (SIFUMHSC) under static and dynamic loadsare studied. The effect of the amount of silica fume on its performance, the strengtheningeffects of silica fume particle artd steel fiber afld their composite effect are discussed. Testresults indicate to a full extent that different amounts of silica fume substituting for cementcan remarkably improve the static and dynamic mechanical behaviour of steel fiberr einforcedSIFUMHSC with other conditions unchanged and that the main reason for the change is thatthe addition of silica fume brings about a double interfacial strengthening effect of fiber-cement matrix and aggregate-cement matrix, thus improving the structure and characteristicsof the interface. When the addition of silica fume is adequate, the H_v-d, I_a-d and CHAS--dcurves tend to be horizontal, with differences disappearing between the interfacial layer andmatrix, so that the size and number of crack sources in the interfacial zone and the wholematrix become smaller and less, and strengthening effects are better deve1oped. This is thekey to the desired performance of steel fiber reinforced SIFUMHSC.

Flexural Fatigue Behavior of Polypropylene Fiber Reinforced Segment Concrete

The influence of polypropylene fiber on the flexural fatigue performance of high-strength concrete (HSC), which could be used as cover of reinforcement of segment, was investigate by three-point load bending tests. Also, the flexural fatigue equations of high-strength concrete with and without polypropylene fiber were established through test analysis. The experimental results indicate that the addition of polypropylene fiber can improve the static bending strength of segment concrete, and the important is that it can markedly increase the flexural fatigue performance of the HSC subjected to cyclic bending load. Especially when with 1.37 kg/m3 addition of the fiber was corporate with silica fume and slag powder, the fatigue life of the HSC can be increased by 43.4% compared to that of the segment concrete without fiber, silica fume and slag.

纳米氧化硅和钢纤维增强再生混凝土损伤模型

以纳米氧化硅和钢纤维为外加材料对再生混凝土进行改良,选定取代率、钢纤维掺量和纳米氧化硅掺量为配合比控制参数,共设计18种工况的再生混凝土。通过棱柱体受压试验分析再生混凝土应力-应变曲线变化特征,建立其损伤本构模型,分析其损伤演化机理。研究表明,随纳米氧化硅掺量增加,应力-应变曲线下降段陡峭,随着钢纤维掺量增加,再生混凝土应力-应变曲线更加饱满,分段表达式可较好表述再生混凝土应力-应变全曲线方程;单掺钢纤维或氧化硅时,随着氧化硅掺量增加,峰值应力增大、峰值应变降低,随着钢纤维掺量增大,峰值应力和峰值应变均增大;复合添加钢纤维和氧化硅时,氧化硅掺量一定时随钢纤维掺量增加,峰值应力和峰值应变均增大,随氧化硅掺量增加,峰值应力和峰值应变不具有明显规律性;建立的损伤本构模型能够较好地满足再生混凝土的应力-应变关系,损伤变量随应变增加呈S型增长,可以较好地反映出再生混凝土某一时段损伤发展。

硅灰和稻壳灰对竹浆纤维水泥基复合材料抗劣化性能的影响

以硅灰和稻壳灰作为掺合料(固定总掺量为40%)、竹浆纤维作为增强材,采用抄取法制备了纤维增强水泥基复合材料,并研究了干湿循环和热水浸泡老化试验下,不同硅灰和稻壳灰掺入比例对竹浆纤维水泥基复合材料力学性能的影响。结果表明:不同掺入比例的硅灰和稻壳灰均有效提高了竹浆纤维水泥基复合材料在干湿循环和热水浸泡老化下的抗弯强度和断裂韧性,其中,单掺40%硅灰的提高效果最好。

钢纤维高强自密实混凝土物理力学性能研究

通过工作性能和力学性能试验研究了硅灰和波纹型钢纤维对自密实混凝土坍落拓展度、T500、J环拓展度、间隙通过性以及力学性能、干缩率的影响。研究发现:2%的硅灰可以提升自密实混凝土的工作性,但掺入4%的硅灰会使J环拓展度大幅度下降;4%的硅灰可以提高28 d抗压强度至94.2 MPa,相对于无硅灰组提升22%;但继续增加硅灰掺量对劈裂抗拉与抗折强度有不利影响;当钢纤维体积掺量达到1.2%时,自密实混凝土坍落拓展度下降55 mm,劈裂抗拉强度、抗折强度和抗压强度较未掺钢纤维试块分别提升17.9%、42.6%和2.5%;自密实混凝土收缩率随硅灰掺量的增加而增加,随钢纤维的增加先增大后减小。

硅灰-玄武岩纤维改性透水混凝土力学性能与耐久性研究

为了探讨不同掺入量的硅灰以及玄武岩纤维对改性透水混凝土的强度、渗透性及耐久性的影响,采用等体积法对不同掺合料进行变量控制,设计9组配合比,分别对抗压强度、孔隙率以及冻融循环质量损失率进行测试。结果表明:适量硅灰以及玄武岩纤维的掺入可以显著提高透水混凝土强度与抗冻性;硅灰等体积替代水泥并不会对混凝土的孔隙率造成巨大影响,掺入过量的纤维会同时损失强度与渗透性;硅灰掺量为10%、玄武岩纤维掺量为2 kg·m^(-3)时,改性透水混凝土的渗透性良好,强度与耐久性能达到最优。

超高性能混凝土的工作性及力学性能影响因素研究

研究了矿渣粉掺量、硅灰掺量、钢纤维掺量和水胶比对超高性能混凝土(UHPC)工作性和力学性能的影响,并通过显著性分析探讨了各因素对UHPC性能的影响程度。结果表明:随着矿渣粉掺量的增加,UHPC的扩展度和28 d抗压、抗折强度均先增大后减小;随着硅灰掺量的增加,UHPC的扩展度和28 d抗压、抗折强度基本呈先增大后减小的趋势;随着钢纤维掺量的增加,UHPC的扩展度降低,28 d抗压、抗折强度增大;随着水胶比的增加,UHPC的扩展度增大,28 d抗压、抗折强度先增大后减小;钢纤维掺量对UHPC力学性能的影响程度最大,水胶比对UHPC工作性的影响程度最大;综合考虑工作性和力学性能,自密实UHPC的最佳配合比为矿渣粉掺量20%、硅灰掺量12%、钢纤维掺量2.0%、水胶比0.18。

矿粉和纤维对活性粉末混凝土工作和力学性能的影响

为研究硅粉和铁尾矿改性混凝土的基本特性,分别用硅粉和铁尾矿粉按照0~20%的比例替代水泥和河砂,并通过力学和氯离子侵蚀实验获得硅粉和铁尾矿粉的较优替代比;然后在此基础上,分别按照体积比为0~2%添加钢纤维、玄武岩纤维和剑麻纤维来改善混凝土的力学特性,结果表明:混凝土的抗压强度和抗拉强度随着硅粉和铁尾矿粉的增加先增后减,其中硅粉和铁尾矿粉的较优替代比分别为15%和10%。三种纤维都能有效地提高混凝土的抗压强度和抗拉强度,但降低混凝土的坍落度。掺入硅粉5%以及10%的铁尾矿粉可以提高混凝土的抗氯离子侵蚀性能,但过多的铁尾矿粉对混凝土的抗氯离子侵蚀性能不利;玄武岩纤维比钢纤维和剑麻纤维能更好地提高混凝土的抗氯离子侵蚀性能,SEM分析也获得相同的结论。

透水混凝土性能影响因素研究

为助力海绵城市的发展,文中针对透水混凝土的几个影响因素进行研究。结果表明,骨料对透水混凝土的透水系数影响最大,使用大粒径骨料可以大幅提高混凝土的透水系数,但会降低混凝土的抗压强度。硅灰替代水泥量小于6%时,混凝土的28d抗压强度随着硅灰用量的增加而增加,硅灰替代水泥量为4%时,混凝土透水系数最大。聚丙烯纤维掺量为0.4%时,混凝土的28d抗压强度最大,掺入少量聚丙烯纤维会降低混凝土的透水系数,但当聚丙烯纤维掺量大于0.2%后,混凝土的透水系数随着聚丙烯纤维用量的增加而增加。混凝土的28d抗压强度随着减水剂用量的增大而增加。减水剂掺量为1.5%时,透水系数达到最小值,之后随着减水剂用量的增加而增加。

Effect of Silica Fume on Mechanical Properties of Concrete Incorporating Steel Slag Powder

This study investigated the effect of silica fume(SF) on mechanical properties of concrete incorporating steel slag powder(SSP). The compressive strength and splitting strength tests of concrete with different content of SF(0%, 4%, 8% and 12%) and of SSP(0%, 10%, 20%, 30% and 40%) were carried out, and the test results were analyzed and fitted. Obtained results showed that the brittleness, compressive strength and compressive strength discreteness of concrete increased due to the incorporation of SF. SSP weakened the compressive strength of concrete, which reduced within 10% when the content of SSP was less than 20%. SF and SSP showed synergistic hydration effect when they were mixed, and the optimal group was SF8 SSP30, whose compressive strength was close to that of plain concrete, and whose brittleness as well as discreteness of compressive strength were lower relatively. With the content of SSF and of SSP as variables, the tension-compression ratio and compressive strength of concrete can be well estimated by surface fitting.

铁路泥石流导流槽抗冲磨混凝土研究

泥石流冲磨会对建筑物构成较大破坏,不同材料组成的混凝土受泥石流冲磨影响不同。为减少冲磨破坏对建筑物的影响,提升建筑物的耐久性,本文对不同强度等级、纤维掺量及表面处理、硅灰掺量的混凝土进行冲磨试验,研究其对混凝土抗冲磨性的影响规律。结果表明,通过提升混凝土强度等级、掺入纤维、表面强化处理及掺入硅灰,可显著提升混凝土的抗冲磨性能。