Status and development of mineral wool made from molten blast furnace slag

This study describes the characteristics of mineral wool and its applications,and also introduces the traditional process of mineral wool made from molten blast furnace （BF） slag. Compared with high energy consumption of the traditional process,the production of mineral wool by using molten BF slag will be able to take full advantage of the sensible heat of molten slag, and also reduce production costs. However, there are also further issues to resolve such as how to obtain the required amount of molten BF slag and how to make it homogeneous. Based on the physical and chemical properties of the molten BF slag,the investigation into the relationship between temperature and viscosity under different acidity coefficients of the slag and silicon mixture was conducted. Combined with the crystallization and phase diagram of slag wool, its heat resistance, water resistance, durability and corrosion resistance were analyzed. Finally, trends of the technology development are proposed.

Damage process and performance of PVA fiber-reinforced alkali-activated slag mortar plate under bending

The effects of unoiled polyvinyl alcohol(PVA)fiber with four different volume fractions of 0%,1.0%,1.5%and 2.0%on the bending properties of alkali-activated slag(AAS)mortar plates were studied.Meanwhile,the acoustic emission(AE)technique and a high-speed camera were utilized to detect the crack development over the complete damage process,and the scanning electronic microscopy(SEM)was used to observe the fiber-matrix interface.Test results show that PVA fibers play a significant role in the toughness improvement of AAS plates.However,the enhancing effect of PVA fibers on the bending behaviour of AAS plates at 120 d is not as remarkable as at early ages.It is observed that the failure process of the PVA fiber-reinforced alkali-activated slag plate can be divided into three stages:elastic stage,main crack formation stage and post-peak load stage.Observations on the fracture surface of specimens indicate that the deterioration process of specimens under bending changed from fiber pull-out at 3 and 28 d to fiber fracture at 120 d.

Laboratory Evaluation of Fiber-Modified Asphalt Mixtures Incorporating Steel Slag Aggregates

Vigorous and continued efforts by researchers and engineers have contributed towards maintaining environmental sustainability through the utilization of waste materials in civil engineering applications as an alternative to natural sources.In this study,granite aggregates in asphaltic mixes were replaced by electric arc furnace(EAF)steel slag aggregates with different proportions to identify the best combination in terms of superior performance.Asphalt mixtures showing the best performance were further reinforced with polyvinyl alcohol(PVA),acrylic,and polyester fibers at the dosages of 0.05%,0.15%,and 0.3%by weight of the aggregates.The performance tests of this study were resilient modulus,moisture susceptibility,and indirect tensile fatigue cracking test.The findings of this study revealed that the asphalt mixtures containing coarse steel slag aggregate exhibited the best performance in comparison with the other substitutions.Moreover,the reinforced asphalt mixtures with synthetic fibers at the content of 0.05%exhibited an almost comparable performance to the unreinforced asphalt mixtures.Modifying the asphalt mixtures with PVA,acrylic,and polyester fibers at the proportion of 0.15%have improved the fatigue cracking resistance by 41.13%,29.87%,and 18.97%,respectively.Also,the fiber-modified asphalt mixtures with PVA,acrylic,and polyester have enhanced the fatigue cracking resistance by about 57%,44%,and 39%,respectively.The results of the resilient modulus demonstrated that as the fiber content increase,the resilient modulus of the reinforced asphalt mixtures decreases.Therefore,introducing synthetic fibers at the content of 0.3%has slightly decreased the resilient modulus in comparison with unreinforced mixtures.On the other hand,the results of the mechanisticempirical pavement design showed that the reinforced asphalt mixes with a high content of synthetic fibers have shown lower service life than the control mixes due to the low resilient modulus.On the contrary,based on the laboratory results,the asphalt mixes incorporating PVA,acrylic,and polyester fibers at the proportion of 0.15%have shown the potential to reduce the thickness of the asphalt layer by about 14.9%,11.80%,and 8.70%,respectively.

Properties and Mechanism on Flexural Fatigue of Polypropylene Fiber Reinforced Concrete Containing Slag

Properties and mechanism were investigated on flexural fatigue of concrete containing polypropylene fibers and ground granulated blast furnace slag（GGBFS）.Four polypropylene fibers’volume fractions and five slag proportions were considered.An experiment was conducted to obtain the fatigue lives at three stress levels in 20 Hz frequency and at a constant stress level of 0.59 in four frequency respectively.Mechanism and evaluation were investigated based on the experimental data.Fatigue life span models were established.The results show that the addition of polypropylene fibers improves the flexural fatigue cumulative strength and fatigue life span.It is proposed that the slag particles and hydrated products improve Interfacial Transition Zone（ITZ）structure and benefit flexural fatigue performance.A composite reinforce effect is found with the incorporation of slag and polypropylene fibers.The optimum mixture contents 55%slag with 0.6%polypropylene fiber for the cumulative fatigue stress.Fatigue properties are decreased as the stress level increasing,the higher frequency reduces the fatigue strength more than lower frequency at a constant stress level.

Effect of content of Al_2O_3 and MgO on crystallization of blast furnace slag during fiber formation

The simulation of blast furnace slag was prepared by pure chemical reagents.Test methods like DSC,XRD and SEM were used to study the effect of Al2O3 and MgO content on crystallization of blast furnace slag during fiber formation.The results show that as Al2O3 and MgO contents in the sample changed,blast furnace slag was crystallized at the average temperature below 1232 K.When the ratio of Mg/Al in the samples is 0.6 calculated by Kissinger equation,crystallization activation energy is at the maximum value and the system is in the most stable condition.The sample crystallization phases are mainly calcium akermanite(2CaO?MgO?2SiO2)and gehlenite(2CaO?Al2O3?SiO2).Secondary crystallization phases are anorthite(CaAl2Si2O8),wollastonite minerals(WOLLA)and pyroxene minerals(cPyrA).Meanwhile,the principal crystallization phases of the samples are different types and have different contents,and the microstructures of the sample sections are different due to the difference between MgO/Al2O3 ratio.

The Influence of CO_(2) Cured Manganese Slag on the Performance and Mechanical Properties of Ultra-High Performance Concrete

The presence of toxic elements in manganese slag(MSG)poses a threat to the environment due to potential pollution.Utilizing CO_(2) curing on MS offers a promising approach to immobilize toxic substances within this material,thereby mitigating their release into the natural surroundings.This study investigates the impact of CO_(2) cured MS on various rheological parameters,including slump flow,plastic viscosity(η),and yield shear stress(τ).Additionally,it assesses flexural and compressive strengths(f_(t) and f_(cu)),drying shrinkage rates(DSR),durability indicators(chloride ion migration coefficient(CMC),carbonization depth(CD)),and the leaching behavior of heavy metal elements.Microscopic examination via scanning electron microscopy(SEM)is employed to elucidate the underlying mechanisms.The results indicate that CO_(2) curing significantly enhances the slump flow of ultra-high performance concrete(UHPC)by up to 51.2%.Moreover,it reduces UHPC’sηandτby rates ranging from 0%to 52.7%and 0%to 40.2%,respectively.The DSR exhibits a linear increase corresponding to the mass ratio of CO_(2) cured MS.Furthermore,CO_(2) curing enhances both f_(t) and f_(cu) of UHPC by up to 28.7%and 17.6%,respectively.The electrical resistance is also improved,showing an increase of up to 53.7%.The relationship between mechanical strengths and electrical resistance follows a cubic relationship.The CO_(2) cured MS demonstrates a notable decrease in the CMC and CD by rates ranging from 0%to 52.6%and 0%to 26.1%,respectively.The reductions of leached chromium(Cr)and manganese(Mn)are up to 576.3%and 1312.7%,respectively.Overall,CO_(2) curing also enhances the compactness of UHPC,thereby demonstrating its potential to improve both mechanical and durability properties.

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.

钢-PVA混杂纤维高性能混凝土抗渗性能试验研究

为探究钢纤维掺量、聚乙烯醇(PVA)纤维掺量和矿粉掺量对钢-PVA混杂纤维高性能混凝土(HFHPC)抗渗性能的影响,本文开展了钢-PVA HFHPC抗渗性能试验,并对试验结果进行了极差分析、方差分析和回归分析。结果表明:对HFHPC抗渗性能的影响程度从高到低依次为钢纤维、矿粉和PVA纤维。在试验水平范围内,得出混凝土试件抗渗性能最佳水平组合:钢纤维体积掺量1.0%、PVA纤维体积掺量0.7%、矿粉质量取代率20%。当钢纤维掺量超1.0%时,HFHPC抗渗性能略有下降,但仍高于基准素混凝土。最后采用多元回归分析,建立了HFHPC渗透系数与钢纤维、PVA纤维和矿粉的预测模型。

钢渣基CO_(2)矿化板材的制备与性能研究

采用铺浆注模、压制脱水成型、CO_(2)养护等工艺措施制备钢渣板材,考察了原材料掺量、脱水压力、养护方式等对钢渣板材力学性能的影响。试验结果表明:水胶比0.35抗折强度最高;随着水泥、熟石灰以及木质纤维掺量的增加,板材的抗折强度均提高;随脱水压力的增加,板材的抗折强度先提高后降低;养护时间延长,板材的抗折强度提高;耐碱玻璃纤维长度减小,板材的抗折强度提高,耐碱玻璃纤维掺量为1.5%时,板材抗折强度最高。

冷热-荷载耦合下纤维锂渣混凝土柱偏心受压性能

为研究冷热循环作用及耦合应力对纤维锂渣混凝土(PLiC)柱偏心受压性能的影响,制作6根PLiC柱和2根对照柱,将其施加0、0.10、0.20、0.35的耦合应力之后,经历0次、100次、200次、300次冷热循环作用后进行偏心受压静力试验,研究冷热循环次数、耦合应力比对PLiC柱偏心受压性能的影响。结果表明:单掺锂渣对试验柱的破坏形态、延性、开裂荷载和极限荷载影响均较小,而掺入1.2 kg/m^(3)的PLiC柱受压破坏时无明显混凝土压溃现象,且变形性能更好,延性提高24.7%、开裂荷载提高3.5倍、极限荷载提高24.73%;耦合应力比不变,冷热循环次数从100次增加到300次时,PLiC柱裂缝数量增加且呈现多而密的特点,延性系数提高8.6%,极限承载力下降33.56%;冷热循环200次时,耦合应力比从0.10增加到0.35,构件延性系数变化较小,极限承载力下降34.55%。试验中冷热循环温差为58℃,可为中国西部地区大温差环境下混凝土结构设计提供一定参考。

纤维地聚物改性粉质黏土无侧限抗压强度试验研究

通过对杭州市某隧道工程开挖产生的废弃粉质黏土添加不同改良剂后开展无侧限抗压强度(unconfined compression strength,UCS)试验,研究了不同矿渣掺量、矿渣-粉煤灰比例、聚丙烯纤维掺量条件下改良土样的抗压强度特性,并对抗压强度形成的机理进行了分析;同时,基于扫描电镜(scanning electron microscope,SEM)试验对表征土体孔隙特征的有关指标展开了定量分析。结果表明:在矿渣掺量为12%时UCS最大,为6738.04 kPa,较素土强度提高80.69倍;粉煤灰的掺入可提高试样后期强度,在K8F2(矿渣/粉煤灰比例80%∶20%)试样中最优;聚丙烯纤维的掺入能有效地改善材料的脆断性能,最优纤维掺量为0.4%。试样孔隙的定向频率在80°~100°区间内分布的概率最大,掺入粉煤灰后定向性较为均匀;孔隙率随着矿渣掺量的增加、地质聚合物中矿渣含量的增多均逐渐减小,在试样K12(矿渣掺量12%)和K8F2中出现最小值;而随着纤维掺量的增加,呈现先降低后升高的趋势,当纤维掺量为0.4%时其值最小,为6.204%;孔隙平均直径主要分布在0~1μm,矿渣掺量增多则小孔隙增多,大孔隙减少;孔隙丰度主要分布在0.4~0.6,孔隙形状主要为椭圆。

改性材料及其掺量对超高性能混凝土力学性能的影响

【目的】优选不同掺量的改性材料,并分析改性后的UHPC抗压强度和破坏形态,制备更加经济型的超高性能混凝土(ultra-high performance concrete,UHPC)。【方法】选取钢渣微粉、河砂、粗骨料、钢纤维作为4种改性材料,设计四因素三水平正交试验,根据正交试验结果制备9种试件;通过力学性能实验,对比分析各试件的抗压强度,优选出改性材料最佳配方并分析UHPC的破坏形态。【结果】钢渣微粉、河砂、粗骨料和钢纤维的加入量(掺量)对试件抗压强度平均值影响的极差分别为7.60、7.57、7.77、0.84,粗骨料、钢渣微粉、河砂对UHPC的抗压强度的影响较大,钢纤维对UHPC抗压强度影响较小。由正交试验结果可知,当钢渣微粉、河砂、粗骨料的加入量分别为210、855、640 kg/m^(3),钢纤维的体积分数(掺量)为1.5%,养护龄期为28 d时,经改性的UHPC抗压强度最大,为134.4 MPa。改性后的UHPC受压破坏时不会瞬间炸裂,整体形态完整。【结论】钢渣微粉和粗骨料的添加能降低改性后的UHPC制造成本,经优化4种改性材料的掺量后UHPC的抗压强度降幅较小,但韧性增强,力学性能得到保障。

聚丙烯纤维加筋增强钢渣混合土性能的研究

为进一步改善钢渣混合土的综合性能,在钢渣混合土中掺入韧性良好的聚丙烯纤维,制备纤维加筋钢渣混合土,研究纤维长度、掺量对钢渣混合土无侧限抗压强度、干缩、抗冻等性能的影响,并采用扫描电镜表征分析加筋对受冻试件微观形貌的影响,探讨加筋纤维增强钢渣混合土综合性能的机理。结果表明:纤维加筋能有效改善钢渣混合土的抗压、干缩及抗冻性能,加筋纤维长度12 mm、掺量0.25%时综合性能相对最优,加筋试件延性变好,抗压强度提升达16.74%;失水量有所增大,但干缩系数减小达37.51%;受冻后质量损失率下降、残余强度比提升达6.33%。此时的试件微观形貌相对完整,故表现出更好的抗干缩和抗冻性能,聚丙烯纤维与基体间有效黏结提供的界面摩擦力及其在基体内形成的立体网状结构是钢渣混合土性能增强的重要基础。

玄武岩纤维对碱矿渣砂浆力学和收缩性能的影响

为加速推进碱激发矿渣(Alkali-Activated Slag,AAS)砂浆的发展和应用,降低其硬化过程中产生的过大收缩,研究了6mm玄武岩纤维对AAS砂浆扩展度、抗折和抗压强度、自收缩、干缩的影响,同时进行了微观扫描电镜测试。结果表明:玄武岩纤维可有效地抑制AAS砂浆干缩并提高其抗折和抗压强度,当玄武岩纤维体积掺量为0.75%时,28d龄期干缩相对降低30%,抗压强度相对提高18.2%。研究还发现,玄武岩纤维会降低AAS砂浆的初始工作度,且还会增大其自收缩。提供了玄武岩纤维对AAS砂浆收缩性能影响的具体规律,为工程实践提供了理论依据。

掺钢渣粉PVA纤维增强水泥基复合材料抗硫酸盐侵蚀性研究

基于钢渣粉的固废再利用,通过掺入不同质量分数的钢渣粉制备PVA-ECC,采用干湿循环加速硫酸盐侵蚀试验、立方体抗压强度试验和轴拉试验,测定分析掺钢渣粉PVA-ECC在Na_(2)SO_(4)溶液(质量分数为5%)中的质量变化、抗压强度、拉伸性能等参数的演变规律,并采用微观扫描电镜(SEM)和X射线衍射仪进行微观形貌与物相分析,探究钢渣粉掺量对PVA-ECC耐硫酸盐侵蚀性能的影响。结果表明:掺钢渣粉PVA-ECC材料中钢渣粉掺量为20%时,质量损失曲线位于基准组以下;低掺量钢渣粉PVA-ECC表现出较好的耐腐蚀性,S20组抗压耐腐蚀系数分别为1.13、1.02、0.96;掺钢渣粉PVA-ECC试件均出现多缝开裂现象,钢渣粉的掺入能在一定程度上提高材料的抗拉强度,S40组最大提高了31.4%;适量钢渣粉的掺入能有效缓解PVA-ECC材料的侵蚀损伤,掺量不超过60%时在研究的龄期范围内材料未出现明显劣化。

水镁石纤维-钢渣细骨料混凝土力学性能研究

为进一步提高钢渣利用率,降低环境污染,针对钢渣细骨料劣化混凝土力学性能现状,引入水镁石纤维,研究不同钢渣细骨料、水镁石纤维掺量对混凝土抗压及抗弯拉强度影响,探讨钢渣细骨料劣化混凝土性能机制,分析水镁石纤维对钢渣细骨料混凝土增强机理。结果表明,随着钢渣细骨料取代率逐步增加,混凝土坍落度下降,抗压强度及抗弯拉强度均不同程度降低。复掺水镁石纤维对钢渣细骨料混凝土的早期强度增强效果明显,与不掺水镁石纤维的30%钢渣混凝土相比,掺入30%钢渣细骨料与0.2%水镁石纤维,混凝土7 d抗压强度及抗弯拉强度分别提高15.75%、10.50%。水镁石纤维可以在水化产物间产生桥接作用,延缓裂纹发展。

PVA胶粉和PP纤维对碱矿渣自流平修补砂浆粘结性能的影响

粘结界面是旧混凝土结构修补后的薄弱环节,是影响修补砂浆与混凝土基体界面粘结性能的重要因素。本文以碱矿渣(AAS)水泥作为胶凝材料制备修补砂浆,通过对流动性、界面弯拉强度、界面拉伸强度、微观形貌等进行测试,研究了聚乙烯醇(PVA)胶粉和聚丙烯(PP)纤维对碱矿渣自流平修补砂浆(ASLRM)界面粘结性能和微观结构的影响。结果表明,PVA胶粉和PP纤维均能有效提高ASLRM的界面粘结性能,二者复掺时,28 d界面弯拉强度最高可提高43.1%,14 d界面拉伸强度最高可提高69.9%。

垃圾焚烧飞灰熔融制保温纤维试验研究

生活垃圾焚烧飞灰中含有Ca、Si、Al、Na等金属氧化物成分,本文提出垃圾焚烧飞灰与垃圾焚烧炉渣、废玻璃配伍熔融制备保温纤维的方法,并进行中试研究。结果表明,辅料的加入降低混合物料的熔点并提高了熔浆的粘度。单独飞灰或飞灰比例过高时无法成纤,随着四辊离心机转速的提高,纤维平均直径会变细,使用80%飞灰+20%炉渣的配方,四辊转速分别为3960 r/min、3960 r/min、4290 r/min、4620 r/min时,纤维平均直径降至6.04μm。熔融得到的保温纤维中重金属得到有效固定,Cr、As、Pb的去除率分别达到了87.6%、96.7%、99.9%。

预制模块化高炉渣纤维保温外墙板传热分析

该研究旨在分析预制模块化高炉渣纤维保温外墙板的传热性能,评估其在建筑保温领域中的应用潜力。通过实验测试获取高炉渣纤维保温外墙板的物理性质和热导率,并进行传热分析。研究发现,预制模块化高炉渣纤维保温外墙板具有较低的热导率和良好的隔热性能。通过传热分析,观察到该外墙板可以有效地减少室内外温度差异,降低热能传递损失。此外,建筑内部的温度稳定性得到改善,达到良好的节能效果。基于传热分析的结果,预制模块化高炉渣纤维保温外墙板在建筑保温领域具备广阔的应用前景,有助于降低能源消耗,并提供舒适的室内环境。该研究为高炉渣纤维保温材料在建筑行业中的应用提供理论支持,为能源节约和减排作出贡献。

PP纤维对疏水性水泥-矿渣复合材料性能的影响

在掺加聚二甲基硅氧烷制备具有疏水性的水泥-矿渣复合材料的基础上,通过掺加不同掺量聚丙烯(PP)纤维,研究对其力学性能、防水性能和耐久性的影响,发现PP纤维掺量为0.4%时,试样的韧性显著提高,28d抗折强度达到7.05MPa,相较于空白组提高了20.7%,同时抗硫酸盐侵蚀性能最佳。当PP纤维掺量为0.2%时,试样的吸水率降低了14.2%,同时抗冻融性能最佳。静态接触角测量结果表明,试样表面的静态接触角未受PP纤维的影响。