高钛重矿渣纤维混凝土力学性能试验研究

考虑纤维掺量、水胶比和粉煤灰掺量3个主要因素,采用正交试验设计20组高钛重矿渣纤维混凝土试件,结合SEM分析研究纤维掺量、水胶比等因素对高钛重矿渣纤维混凝土力学性能的影响。试验结果表明:水胶比对高钛重矿渣混凝土的抗折与抗压强度影响最大;玄武岩纤维可以显著提高高钛重矿渣混凝土抗折强度,塑钢纤维可以明显提高高钛重矿渣混凝土抗压强度。当水胶比为0.32,玄武岩纤维掺量1 kg,粉煤灰掺量5%时,高钛重矿渣纤维混凝土抗折强度为5.61 MPa,比未掺纤维的高钛重矿渣混凝土提高10%。当水胶比为0.34,塑钢纤维掺量2 kg,粉煤灰掺量5%时,高钛重矿渣混凝土的抗压强度为60.45 MPa,达到GB50010—2010《混凝土结构设计规范》规定的C55等级。     

激发剂对SCM-Ⅰ型炉渣基胶凝材料强度特性的影响

以炉渣基复合胶凝材料为主要原料, 研究不同激发剂对SCM-Ⅰ型胶凝材料的激发效果并通过XRD与SEM分析, 从微观结构与水化产物的角度探讨不同激发剂对SCM-Ⅰ型胶凝材料强度的影响.结果表明:碱激发剂中氢氧化钠与氢氧化钙均具有一定的激发效果，添加氢氧化钙比未添加激发剂的28 d抗压强度提高了34.77 %，而硅酸钠对强度的提高起到了抑制作用，在其掺量为0.75 %时，抗压强度下降了45.15 %，添加0.50 %硫酸钠的28 d抗压强度提高7.90 %，激发效果并不明显.氯盐激发剂中，添加1.00 %的氯化钙与氯化钠，分别比未添加激发剂的28 d抗压强度提高了68.08 %与5.62 %.添加氯化钙后促水化反应的进一步进行，并生成大量的钙矾石；添加硅酸钠后抑制了C-S-H凝胶的生成，降低了胶凝材料的强度.      

水玻璃模数对碱激发赤泥胶凝材料性能影响研究

为探究赤泥回收利用方法,以烧结法赤泥为活性材料,不同模数的水玻璃溶液为激发剂,制备了赤泥基碱激发胶凝材料,测试了其力学性能及孔结构特征,并通过XRD、SEM及差热分析探究了其微观机理。试验表明,水玻璃模数对材料性能有较大影响,水玻璃模数为0.96时体系的激发效果最好,28 d抗压强度达到10.21 MPa。硬化试件的主要强度来源物质为水化硅酸钙凝胶,强度较高的材料其微观结构更为致密,碱激发产物数量更多。     

粉煤灰混凝土小型空心砌块研究

为能降低混凝土主砌块的容重,又能满足框架结构房屋墙体要求,并能大量利用粉煤灰,进行了粉煤灰混凝土小型空心砌块研究。试制出粉煤灰掺量４５％以上,炉渣掺量３０％以上,综合利废率７５％以上,强度达ＭＵ３．５的粉煤灰人心砌块,介绍了所用原材料、配合比及砌块的物理力学性能。指出粉煤灰掺量、胶结料配比、胶骨比等是影响质量的主要因素。     

钢渣碳化砖的碱激发-碳化协同作用机制

摘要：以钢渣为原料,标准砂为骨料,碳酸钠为碱激发剂,基于碱激发 碳化协同作用制备钢渣碳化砖。采用X射线衍射、热重/差示扫描量热分析、压汞法以及扫描电子显微镜分别对试样的物相组成、孔隙率以及微观形貌进行表征。通过对比研究“碱激发”、“碳化”以及“碱激发+碳化”作用对试样强度、产物组成、孔隙率以及微观形貌的影响,对碱激发 碳化协同作用机制进行深入探讨。结果表明,碳酸钠可激发钢渣胶凝活性,生成薄片状水化硅酸钙（C-S-H）凝胶,为试样提供初始性能。碳化过程中生成的CaCO3等反应产物对试样具有“填充效应”,这是试样强度性能提高的主要原因。碱激发过程中生成的C-S-H凝胶为碳化反应提供碳化源,促进碳化反应的发生;碳化反应利用碱激发反应产物C-S-H凝胶为碳化源,生成CaCO3等反应产物,使基体致密程度提高,从而使试样性能得到进一步优化。     

高钛重矿渣隧道喷射混凝土力学性能试验研究

利用高钛重矿渣作为骨料制作高钛重矿渣隧道喷射混凝土。试验表明，在粉煤灰、钢纤维掺量一定的情况下，0.34～0.4的水胶比范围内，高钛重矿渣隧道喷射混凝土的适宜水胶比为0.38。掺加波浪型钢纤维可以增强高钛重矿渣隧道喷射混凝土的力学性能，降低高钛重矿渣隧道喷射混凝土回弹率。高钛重矿渣隧道喷射混凝土水化产物主要为C-S-H凝胶和钙矾石，C-S-H凝胶和钙矾石填充在高钛重矿渣碎石和高钛重矿渣砂之间的缝隙，将钢纤维包裹形成较为密实的整体，提高了高钛重矿渣隧道喷射混凝土抗折强度和劈裂强度，降低了高钛重矿渣隧道喷射混凝土的回弹率。     

激发剂对赤泥-黄金尾矿-碱矿渣体系性能的影响

为提高危险固体废弃物的综合利用水平,依据赤泥、黄金尾矿以及矿渣三种固体废弃物的特性,研究NaOH、KOH和Na2SiO3三种激发剂对赤泥-黄金尾矿碱矿渣体系的性能影响。并在此基础上通过XRD、FT-IR、TGA/DSC和SEM等表征手段明晰其微观反应机理。结果表明,当Na2SiO3作为激发剂时,复合胶凝材料体系的激发效果最好,标养3天的胶砂抗折强度和抗压强度分别达到5.5和23.5 MPa;标养28天的胶砂试件抗折强度和抗压强度分别为8.8和43.21 MPa,可达到P?I42.5水泥强度指标。通过微观分析得知,试件的主要强度来源物质为钙矾石和水化硅铝酸钙凝胶,力学性能高的材料其微观结构更为密实,碱激发水化产物数量更多。     

废弃玻璃粉对水泥砂浆力学性能的影响

废弃玻璃经球磨机研磨成粉可作为水泥砂浆的原料.本文通过正交试验研究了废弃玻璃粉掺量(0、10%、20%、30%)、水胶比(0.35、0.4、0.5、0.6)、胶凝总量(420、450、480、500 kg/m~3)和玻璃着色剂种类等因素对水泥砂浆的力学性能影响规律.结果表明,随着废弃玻璃粉掺量的增加,砂浆试块的抗压强度先增大后降低.最佳玻璃粉掺量为10%,水胶比为0.4,胶凝总量为450 kg/m~3;对废弃玻璃粉水泥砂浆强度影响最显著的因素为玻璃粉掺量,其次为水胶比,而胶凝材料总量和着色剂对强度的影响很小.废弃玻璃粉的火山灰活性效应不明显.利用废弃玻璃粉作为掺合料生产水泥砂浆是可行的.     

锰渣基地质聚合物的制备研究

对以锰渣作为基础原料的地质聚合物进行制备研究,通过测试其胶砂试块强度,分析不同锰渣掺量的锰渣基地质聚合物力学性能,利用SEM、XRD等方法分析该类聚合物的反应产物.实验表明:该类地质聚合物锰渣掺量80%为最佳;制备得到的地质聚合物前期强度发展较快,抗折强度5 MPa以上,抗压强度62.5 MPa以上.     

大掺量粉煤灰混凝土在生产中的应用

简述了粉煤灰在混凝土中的作用机理及在生产中的应用,说明了大掺量混凝土用水量低、水胶比低、泌水率低,是质量优良耐久性好的高性能化混凝土,且具有良好的工作性能和早期抗裂性能.开发大掺量粉煤灰,对促进混凝土技术发展,提高建筑质量,加强环境保护有重要意义.     

铁尾矿粉制备高延性纤维增强水泥基复合材料

探索采用铁尾矿粉取代粉煤灰作为矿物掺合料制备高延性纤维增强水泥基复合材料（ECC）的可行性,重点研究铁尾矿粉掺量对ECC的拉伸特性和抗压强度的影响,并比较所研发的新型铁尾矿粉ECC与传统粉煤灰ECC的宏观力学性能.研究发现,采用铁尾矿粉作为矿物掺合料制备高延性纤维增强水泥基复合材料是可行的.在同等矿物掺合料掺量下,铁尾矿粉ECC的强度性能低于粉煤灰ECC,但表现出更强的拉伸延性.在所研制的铁尾矿粉ECC中,当铁尾矿粉与水泥质量比为1.2-2.2时,ECC的28 d抗压强度为36.7-54.2 MPa,满足一般混凝土结构对抗压强度的要求.此时,ECC的28 d极限拉伸应变为3.4%-4.3%,铁尾矿的总用量占固体基体原材料总质量的66.6%-77.0%.      

电厂灰渣制备井下膏体充填材料试验研究

为了探究不同灰渣对充填体强度的影响,将流化床底渣、流化床飞灰和粉煤灰按不同比例混合,作为充填骨料,普通硅酸盐水泥作为胶结材料,加水制备膏体材料,进行流动度测试和抗压强度试验。结果表明：（1）流化床灰渣中含有部分胶凝成分,粉煤灰具有减水作用和一定的火山灰活性,二者均为良好的井下充填材料。（2）当膏体材料含水率超过其饱和含水率时,膏体流动性会大幅提高,充填材料发生离析、脱水,导致充填体强度降低。（3）当流化床底渣、飞灰和粉煤灰配比为6∶2∶1,水泥含量为10%,料浆浓度为73%时,坍落度为20 cm,充填体28 d强度可达3.3 MPa。此配比在满足料浆流动度和充填体强度要求的同时,使充填成本大幅降低。（4）将上述配比作为对照组,进行级配优化试验,将原状底渣进行破碎后作为细骨料,以不同比例取代原状底渣。当底渣破碎至粒径小于等于5 mm,取代率为10%~15%时,充填体7 d强度达到2.4 MPa,28 d强度可达3.5 MPa,充填体强度明显提高。该研究结果为电厂灰渣在黄金矿山充填工程中的应用提供了参考和借鉴。     

Stabilization of Organic Soils with Fly Ash

The effectiveness of fly ash use in the stabilization of organic soils and the factors that are likely to affect the degree of stabilization were studied. Unconfined compression and resilient modulus tests were conducted on organic soil–fly ash mixtures and untreated soil specimens. The unconfined compressive strength of organic soils can be increased using fly ash, but the amount of increase depends on the type of soil and characteristics of the fly ash. Resilient moduli of the slightly organic and organic soils can also be significantly improved. The increases in strength and stiffness are attributed primarily to cementing caused by pozzolanic reactions, although the reduction in water content resulting from the addition of dry fly ash solid also contributes to strength gain. The pozzolonic effect appears to diminish as the water content decreases. The significant characteristics of fly ash that affect the increase in unconfined compressive strength and resilient modulus include CaO content and CaO/SiO2 ratio [or CaO/(SiO2+Al2O3) ratio]. Soil organic content is a detrimental characteristic for stabilization. Increase in organic content of soil indicates that strength of the soil–fly ash mixture decreases exponentially. For most of the soil–fly ash mixtures tested, unconfined compressive strength and resilient modulus increased when fly ash percentage was increased.     

粉煤灰改性高水材料力学性能试验研究及机理分析

为解决矿山高水充填材料成本较高、粉煤灰等工业废料大量剩余造成资源浪费、环境污染等问题,借助微机控制电子万能试验机(ETM)力学试验系统、扫描电镜扫描装置和X射线衍射分析仪,研究粉煤灰掺量对高水材料物理力学性能的影响规律,并通过物相和微观结构分析探讨其影响机理.结果表明:随着粉煤灰掺量的增加,高水材料的凝结时间逐渐延长,含水率逐渐降低,容重基本不变;掺杂粉煤灰前后高水材料均是一种弹塑性材料,其变形破坏过程可以分为孔隙压密阶段、弹性阶段、屈服阶段和破坏阶段;高水材料的峰值强度、弹性模量和变形模量均随粉煤灰掺量的增加略有降低,残余强度却有所提高;综合考虑高水材料的强度、模量和成本,粉煤灰掺量a为15%是最优掺量,此时峰值强度、弹性模量和变形模量仅分别降低了25%、8.6%和10%,残余强度却提高了50%.物相和微观形貌分析结果表明:粉煤灰的掺量影响了β-C₂S的水化进程,导致钙矾石生成量减少,其他水化产物生成量增多,进而破坏了钙矾石结构的整体性和均匀性,最终降低了高水材料的抗压强度.      

Strength Characteristics of Class F Fly Ash Modified with Lime and Gypsum

This paper presents the shear strength characteristics of a low lime class F fly ash modified with lime alone or in combination with gypsum. Unconfined compression tests were conducted for both unsoaked and soaked specimens cured up to 90 days. Addition of a small percentage of gypsum (0.5 and 1.0%) along with lime (4–10%) enhanced the shear strength of modified fly ash within short curing periods (7 and 28 days). The gain in unsoaked unconfined compressive strength (qu) of the fly ash was 2,853 and 3,567% at 28 and 90 days curing, respectively, for addition of 10% lime along with 1% gypsum to the fly ash. The effect of 24?h soaking showed reduction of qu varying from 30 to 2% depending on mix proportions and curing period. Unconsolidated undrained triaxial tests with pore-pressure measurements were conducted for 7 and 28 days cured specimens. The cohesion of the Class F fly ash increased up to 3,150% with addition of 10% lime along with 1% gypsum to the fly ash and cured for 28 days. The modified fly ash shows the values of Skempton’s pore-pressure parameter, Af similar to that of over consolidated soils. The effects of lime content, gypsum content, and curing period on the shear strength parameters of the fly ash are highlighted herein. Empirical relationships are proposed to estimate the design parameters like deviatoric stress at failure, and cohesion of the modified fly ash. Thus, this modified fly ash with considerable shear strength may find potential use in civil engineering construction fields.     

低浓度拜耳赤泥充填材料制备及水化机理

针对矿山充填中拜耳法赤泥利用率较低或低浓度赤泥充填材料存在强度低、泌水量高、易收缩等问题,研究粉煤灰添加比例、脱硫石膏、石灰及激发剂对赤泥充填材料早期强度及体积稳定性的影响,采用扫描电子显微镜-能谱仪（SEM-EDS）和X射线衍射（XRD）分析手段探讨赤泥基充填材料的水化机理。结果表明,脱硫石膏促进钙矾石的生成,石灰促进粉煤灰火山灰效应,激发剂可以加快赤泥?粉煤灰水化反应进程,三者协同作用提高赤泥充填体强度。充填材料28 d抗压强度3.35 MPa,且初始及60 min流动度在200 mm以上。微观实验表明,硬化体水化产物为钙矾石、硬柱石、硅铝酸盐凝胶类矿物,水化产物通过填充孔隙,提高浆体强度。赤泥基充填材料固体废弃物利用率达到92%,无泌水,无沉缩,具有较高的经济价值和环保价值。      

Polymer Concrete Using Coal Fly Ash

The disposal of coal combustion byproducts wastes has been a pressing issue during the past few decades. In parallel, the formulation of high-performance materials that are stronger and more durable than conventional cement-based materials has emerged as an issue of considerable importance in the construction industry. This paper shows that it is possible to utilize fly ash, a byproduct of coal burning, to produce a high-performance material at a potentially lower cost and without compromising its structural integrity. The high-performance material reported in this study is polymer concrete (PC) made with fly-ash fillers. The PC is investigated for its compressive strength, flexural strength, creep deformation, and bond strength of PC overlay on portland cement concrete under thermal cycling. The use of fly ash as an aggregate in PC is very promising because it enhances the physical properties of the material and particularly its compressive and flexural strength. PC using fly ash could be used as an overlay in pavement, bridges, and runways or in precast applications such as utility, transportation, and hydraulic components.     

Autoclaved Aerated Concrete Produced with Low NOx Burner∕Selective Catalytic Reduction Fly Ash

Electric utility coal combustion processes employing low NOx burner and high-dust selective catalytic reduction (SCR) emission control technologies produce fly ash that is high in carbon and ammonium salt content. Such ash is considered undesirable for use as admixture in standard concrete because of its decreased compressive strength and ammonia odor. This research investigates the use of low NOx burner∕SCR fly ash for production of autoclaved aerated concrete (AAC). For this study, samples were obtained from the Orlando Utility Commission's Stanton Power Generation Plant Unit 2, which contained 6% carbon and 28 mg of ammonium ion∕kg fly ash. A number of AAC recipes were developed with this ash, producing blocks with compressive strength values ranging from 2.268 to 4.435 kPa and densities ranging from 560 to 812 kg∕m3. During block production, carbon particles in the ash exhibited hydrophobic properties and separated from water at the AAC slurry∕gas bubbles boundary that is produced in the rising cake. Separated carbon was unable to physically interfere with calcium silica hydrate gel formation occurring in the slurry. In addition, the alkaline environment inside the reactive AAC slurry was sufficiently high to cause the release of ammonia gas. Consequently, ammonia odor was not observed during the later setting of an undisturbed block or during curing stages of the finished block. The toxicity characteristic leaching procedure and synthetic precipitation leaching procedure were found to be below the appropriate toxicity thresholds. In general, toxicity characteristic leaching procedure concentrations were higher than synthetic precipitation leaching procedure concentrations for all samples and all analytes (As, Ba, B, Cd, Cr, Ni, and Pb). It is concluded that the high carbon, ammonia bearing fly ash from the Stanton Unit 2 Low NOx burner∕SCR pulverized coal combustion process is a suitable source of siliceous material for the production of AAC prototype block, from physical, environmental, and aesthetic perspectives.     

页岩提钒尾渣-赤泥混合煅烧制备地聚物研究

页岩提钒尾渣和赤泥等固体废弃物的大量堆存会给周围环境带来严重威胁,亟待综合处理。页岩提钒尾渣和赤泥均含有硅酸盐、铝硅酸盐矿物,具有作为制备地聚物原料的可能性。对页岩提钒尾渣和赤泥进行煅烧活化,再在碱激发剂的作用下制备地聚物。研究表明:混合煅烧能有效提高页岩提钒尾渣和赤泥的活性,增强地聚物强度。在页岩提钒尾渣与赤泥质量比为4∶6时,制备的地聚物七天抗压强度能够达到32.41 MPa,满足MU30普通混凝土小型砌块的强度要求。为协同利用多种固废提供了可供借鉴的方法。     

粒度分布对大掺量矿渣、钢渣胶凝体系抗压强度影响的灰色关联分析

为了能够更好地大量利用矿渣、钢渣制备高强建筑材料,实验采用灰色关联分析方法研究了矿渣、钢渣的粒度分布对大掺量矿渣、钢渣胶凝体系抗压强度的影响.矿渣和钢渣掺量分别占胶凝材料总质量的50%和30%,水胶比为0.34.研究表明:粒度小于8.39μm的矿渣、钢渣颗粒对其胶凝体系3 d和28 d抗压强度均起到增强作用,大于8.39μm的矿渣、钢渣颗粒对抗压强度起到削弱作用.为了提高大掺量矿渣、钢渣胶凝体系28d抗压强度,应当主要增加5.03~8.39μm矿渣、钢渣颗粒数量.