纤维增强发泡保温复合材料的制备与性能

为了增强玻化微珠/水泥发泡保温复合材料的力学性能和保温性能,通过掺加改性物理泡沫降低发泡保温复合材料的密度和导热系数,采用改性纤维对发泡保温复合材料进行增强。研究了纤维增强发泡保温复合材料的力学性能和耐水性能,并利用扫描电镜对试样内部微观形貌进行观察,探讨了改性泡沫和改性纤维对发泡保温复合材料的增强机制。结果表明,掺加泡沫明显降低了发泡保温复合材料的密度和导热系数,当泡沫掺量为1.05 mL/g时,试样密度和导热系数分别为186 kg/m³和0.056 W/（m·K）。泡沫改性可有效改善发泡保温复合材料的强度和软化系数,掺加改性泡沫试样的抗折强度、抗压强度和软化系数较掺加乳胶粉试样的分别提高了21.05%、21.43%和13.56%。改性纤维可显著提高发泡保温复合材料的强度和软化系数,掺加改性纤维试样的抗折强度、抗压强度和软化系数较掺加未改性纤维试样的分别提高了25.93%、13.51%和8.33%。     

大掺量自来水厂污泥粉对混凝土强度和微观结构的影响

以煅烧后的自来水厂污泥粉(CWTS)取代部分水泥制备大掺量污泥粉混凝土，研究了大掺量CWTS对于混凝土强度、孔结构和纳米力学性能的影响。结果表明：尽管大掺量CWTS不利于混凝土的28天抗压强度发展，但是20wt%和40wt%的CWTS能够增强混凝土的90天抗压强度；由于CWTS的火山灰活性和填充作用，掺有20wt%～40wt%CWTS的混凝土90天孔结构被明显细化，大于1μm的孔隙含量明显减少；同时，从纳米尺度特征中观察到掺加20wt%CWTS能够明显降低基体中孔隙相和未水化相含量，并提高C-S-H相的体积分数，特别是高密度C-S-H相；此外，掺加20wt%的CWTS能够使界面过渡区(ITZ)宽度相对降低20%，并且掺加40wt%CWTS的实验组与对照组(0wt%CWTS)具有相似的ITZ宽度。由此可见，使用大掺量(20wt%～40wt%) CWTS取代水泥制备混凝土，不仅具备较好的经济和环境效应，也有益于其90天力学性能和微结构的改善。     

超细粉体对水泥基材料力学性能的影响

为了研究超细粉体在水泥基材料中的应用,对掺加不同活性超细粉体的水泥基试件进行了抗压强度和抗折强度的测试,讨论了矿粉A掺量、硅粉掺量、复掺矿粉A和硅粉对水泥基材料力学性能的影响。结论表明:活性超细粉体对水泥基试件的抗折和抗压强度有较大影响,尤其是硅粉能够很好地提高试件的抗折强度和抗压强度。通过SEM形貌分析,说明掺加的超细粉体能够与水泥基材料内部的不利成分Ca(OH)2发生二次水化反应,生成有利的C-S-H凝胶,有效改善水泥基材料的微观结构。     

玉米秸秆纤维/脱硫石膏复合材料的性能

采用玉米秸秆纤维作为脱硫建筑石膏的增强材料, 通过力学性能测试实验研究了不同掺量秸秆纤维对石膏基复合材料力学性能的影响, 讨论了秸秆纤维的增强机制。结果表明, 秸秆纤维的掺量为5%时, 试样的抗折强度和抗压强度较空白样分别提高了92.31%和7.14%; 采用碱处理法、 聚丙烯酰胺化学包覆法、 丙烯酸化学包覆法对秸秆纤维进行表面改性, 通过力学性能测试实验和扫描电镜微观形貌观察研究了纤维表面改性对石膏基复合材料力学性能的影响。结果表明, 纤维表面改性改善了复合材料的界面结合状况, 进一步提高了复合材料的力学性能, 丙烯酸化学包覆改性可使脱硫建筑石膏复合材料的抗折强度较未改性玉米秸秆纤维/脱硫石膏复合材料提高55.71%, 抗压强度提高22.99%。      

石灰基材料对生土改性效果及机制研究

针对当前石灰、矿渣、粉煤灰等作为生土改性剂的研究主要是在力学性能及耐久性等宏观性能方面,尝试从上述改性材料对生土改性前后的矿物组成、官能团特征峰、微观结构等微观角度来阐述生土改性的内在作用机制。试验结果表明,(1)单掺石灰时,生土改性效果随石灰掺量增加而提高,最佳掺量为10%,其28 d抗压强度和软化系数分别达到3.69 MPa和0.80,原因是其板状的Ca(OH)_2水化产物填充生土颗粒间的空隙,达到饱和后的Ca(OH)_2仅其骨架作用;(2)当10%石灰分别复掺5%矿渣和5%粉煤灰时,28 d抗压强度分别增长了8.1%和2.4%,软化系数分别达到了0.92和0.90,原因是粉煤灰和矿渣发生二次水化反应,其中Mg—O、Al—O等键断裂,Al~(3+)、Mg~(2+)等阳离子与Ca(OH)_2发生置换反应,致使1 436.47 cm~(-1)处的峰位偏移至1 400 cm~(-1)附近,同时出现了1 030 cm~(-1)附近的C-S-H凝胶特征峰以及3 120 cm~(-1)处左右的火山灰反应特征峰;(3)掺矿渣改性效果优于单掺石灰,而复掺粉煤灰的改性效果不佳。     

砒砂岩对硅酸盐和硫铝酸盐水泥性能的影响

为了研究砒砂岩对硅酸盐水泥和硫铝酸盐水泥物理性能的影响,采用单因素多水平梯度实验,通过不同砒砂岩掺量的对比,测定硅酸盐水泥和硫铝酸盐水泥的凝结时间、标准稠度用水量和胶砂强度等性能。结果表明:砒砂岩对硅酸盐水泥和硫铝酸盐水泥皆有促凝作用,当砒砂岩掺量质量分数为5%时硅酸盐水泥的初凝时间会缩短30%,硫铝酸盐水泥初凝时间缩短47%,硅酸盐水泥和硫铝酸盐水泥的标准稠度用水量分别增加6.6%和21.7%;砒砂岩掺量质量分数为10%时,硅酸盐水泥的3 d和28 d的强度分别增加7.2%和6%,对其力学性能有较大影响;掺入砒砂岩后,硫铝酸盐水泥强度降低,且随掺量增加,抗压强度降幅增大。     

碱激发再生砖粉地聚物的抗压强度与微观特性

废弃黏土砖在建筑垃圾中占有较高比例，经过破碎、研磨后得到的再生砖粉存在火山灰活性，可作为地聚物的原料进行使用。采用正交实验方法研究矿物掺合料、激发剂、水与胶凝材料的质量比(水胶比)等因素对再生砖粉地聚物抗压强度的影响，并通过X射线衍射、扫描电镜能谱、红外光谱等微观手段系统地进行表征。结果表明：矿粉取代率、水玻璃掺量对再生砖粉地聚物抗压强度影响显著；矿粉取代率的提高，促使水化硅铝酸钠凝胶向水化硅铝酸钙凝胶转变，提高再生砖粉地聚物的抗压强度；高钙体系再生砖粉地聚物中含钠的水化硅铝酸钙、水化硅酸钙等多种凝胶与Ca(OH)₂晶体共存；偏高岭土的掺入促进含钠的水化硅铝酸钙凝胶的生成，提高聚合反应程度，延缓裂缝的生长，内部微结构得到较大改善，利于强度的发展。     

用粉煤灰和铁尾矿制备高强混凝土

以粉煤灰和铁尾矿为主要原料制备高强混凝土,用X射线衍射（XRD）和扫描电镜（SEM）分析材料的水化产物和微观形貌,研究了铁尾矿掺量、水胶比、高效减水剂用量对高强混凝土力学性能的影响。结果表明,混凝土的抗压强度为100.1 MPa,抗折强度为20.6 MPa,固体废弃物掺量达86.4%;在水化过程中大量C-S-H凝胶和钙矾石的生成为细骨料混凝土提供了早期强度,火山灰活性反应对Ca（OH）₂的消耗是混凝土后期强度持续提高的主要原因。     

赤泥复合充填材料浸出行为及固化机制

针对赤泥高碱性、化学成分复杂、资源化利用率低的问题,以赤泥协同粉煤灰等多固废制备矿山充填材料,对比研究赤泥复合材料配比对充填体抗压强度的发展规律,采用XRD、SEM等微观分析手段揭示充填材料水化机制,通过淋溶试验、毒性浸出试验探明充填体固碱机制、浸出行为及毒害离子固化机制。结果表明：赤泥复合材料质量比为赤泥∶粉煤灰∶水泥=3:7:0.4时,充填体3、7、28天抗压强度分别为0.76、1.35、1.87 MPa,材料成本为78.08元/吨,满足矿山充填开采要求。在赤泥-粉煤灰-水泥的协同互锁作用下,充填体生成了以水化硅酸钙(C-S-H)凝胶、钙矾石、钠系菱沸石为主的水化产物,且赤泥∶粉煤灰质量比越小,粉煤灰比表面积越大,充填体结构越致密,固碱效果越好。钙矾石和C-S-H凝胶通过物理固封和化学结合的形式,使赤泥复合材料毒性离子浸出浓度满足固废要求。     

钢渣激发脱硫石膏水硬性胶凝材料的研究

研究旨在开发一种以钢渣为碱性激发剂,以烟气脱硫石膏、矿渣粉为主要为原料的脱硫石膏水硬性胶凝材料。该胶凝体系3天抗折强度和抗压强度可达4.4 MPa和15.8 MPa;28天抗折强度和抗压强度可达9.4 MPa和50.7 MPa。其试样的强度随钢渣掺量的增加而增加,而钢渣含量一旦超过8%后,增长幅度变缓,甚至开始降低。XRD和SEM分析表明,脱硫石膏-矿渣-激发剂体系的水化产物主要是钙矾石和C-S-H凝胶。脱硫石膏在水化过程中一部分参与水化形成水化产物钙矾石,其余部分被水化产物所包裹起集料骨架作用。     

碳酸化钢渣和矿渣作硅酸盐水泥混合材水化性能研究

通过对钢渣碳酸化前后的硅酸盐相提取及水化放热性能和将碳酸化钢渣和矿渣作为混合材的硅酸盐水泥的胶砂强度和水化产物种类的测定,以及对它们微观形貌的观察,研究了碳酸化钢渣对胶凝体系水化性能的影响.结果表明,碳酸化使钢渣中硅酸盐相的含量由47.06％下降至14.38％;碳酸化促进了钢渣的早期水化,抑制其后期水化;在配比相同的条件下,碳酸化钢渣-矿渣-硅酸盐熟料体系试样的3、28d抗压强度较未碳酸化钢渣-矿渣-硅酸盐熟料体系试样的高;碳酸化生成的CaCO3促进了熟料的水化;碳酸化钢渣促进了胶凝体系中AFt的生成,且生成水合碳铝酸钙.     

矿物掺合料对地聚合物抗冻性能的影响

以碱激发偏高岭土制备地聚合物混凝土,分别研究了掺入15%的钢渣、矿渣或粉煤灰的地聚合物混凝土的力学抗压强度和抗冻性能,测试了地聚合物混凝土的真空饱水体积吸液率,运用XRD、SEM和DSC-TG等测试方法分析了矿物掺合料对地聚合物微观结构和水化产物的影响。结果表明:钢渣或矿渣能有效提高地聚合物混凝土的抗压强度,而粉煤灰的掺入使其强度稍有降低;地聚合物表观形貌中存在较多的孔洞和微裂缝导致其抗冻性能较差,掺入钢渣或者矿渣后地聚合物形成了新的产物C-S-H凝胶、C-A-S-H凝胶等并填充在结构中形成更加密实的板状结构,降低了地聚合物混凝土冻融破坏速率,五次冻融循环后地聚合物的相对强度均在90%以上,抗冻性能得到提高;粉煤灰降低了制备地聚合物混凝土的用水量且未水化的粉煤灰颗粒镶嵌在结构中增加了其密实性和抗冻性能,五次冻融循环后相对强度为86.9%,基准组的相对强度仅为79.7%。     

聚乙烯醇纤维增强钢渣粉-水泥复合材料基本力学性能及微观结构

通过掺加钢渣粉来制备聚乙烯醇（PVA）纤维增强钢渣粉-水泥基复合材料,从宏微观两个方面研究了这种复合材料的性能。考虑了基体材料的水胶比（0.25和0.35）、不同钢渣粉质量分数（0、30wt%、60wt%、80wt%）,采用抗压强度试验、薄板四点弯曲试验研究了PVA纤维增强钢渣粉-水泥基复合材料的基本力学性能变化规律及其在弯曲荷载作用下的裂缝控制能力,采用扫描电镜观测了破坏后试样的微观结构。结果表明,水胶比和钢渣粉掺量均可明显影响PVA纤维增强钢渣粉-水泥基复合材料的基本力学性能,在低水胶比条件下（水胶比为0.25）,钢渣粉掺量达到80wt%时,试样表现出较高的韧性指数和良好的裂缝控制能力,基本满足工程所需强度要求,水胶比为0.35时钢渣掺量不宜超过60wt%;同时,从节能减排的角度考虑,利用钢渣粉制备PVA纤维增强钢渣粉-水泥基复合材料是可行的。      

氧化石墨烯/再生水泥基复合材料的制备

基于建筑垃圾再生细骨料替代天然砂,进行氧化石墨烯(GO)改性再生水泥基复合材料的综合物理性能和水化机制研究。采用超声分散GO及振动搅拌制备再生水泥基复合材料,综合耐久性能测试结果表明:和不掺GO再生水泥基复合材料相比,添加0.03% GO改性7 d龄期强度的GO/再生水泥基复合材料抗折和抗压强度分别提高了16%和21%;添加0.02% GO改性的28 d龄期强度的GO/再生水泥基复合材料抗折和抗压分别提高了13.7%和13.6%。GO/再生水泥基复合材料龄期7 d耐候、50次冻融循环后力学性能均良好;氯离子含量皆小于0.06%。放射性检测结果表明:GO/再生水泥基复合材料内照射指数I_Ra和外照射指数I_r均属于A类建筑材料。通过XRD、TG-DTA、SEM等手段对GO/再生水泥基复合材料水化机制研究表明:GO促进了钙矾石(AFt)晶体的大量生成及胶凝孔中存在更多的自由水,且对后期氢氧化钙(CH)的产生有抑制作用,进而提高了GO/再生水泥基复合材料综合物理性能。      

Accelerated carbonation and performance of concrete made with steel slag as binding materials and aggregates

Steel slag has been used as supplementary cementitious materials or aggregates in concrete. However, the substitution levels of steel slag for Portland cement or natural aggregates were limited due to its low hydraulic property or latent volume instability. In this study, 60% of steel slag powders containing high free-CaO content, 20% of Portland cement and up to 20% of reactive magnesia and lime were mixed to prepare the binding blends. The binding blends were then used to cast concrete, in which up to 100% of natural aggregates (limestone and river sands) were replaced with steel slag aggregates. The concrete was exposed to carbonation curing with a concentration of 99.9% CO₂ and a pressure of 0.10 MPa for different durations (1d, 3d, and 14d). The carbonation front, carbonate products, compressive strength, microstructure, and volume stability of the concrete were investigated. Results show that the compressive strength of the steel slag concrete after CO₂ curing was significantly increased. The compressive strengths of concrete subjected to CO₂ curing for 14d were up to five-fold greater than that of the corresponding concrete under conventional moist curing for 28d. This is attributed to the formation of calcium carbonates, leading to a microstructure densification of the concrete. Replacement of limestone and sand aggregates with steel slag aggregates also increased the compressive strengths of the concrete subjected to CO₂ curing. In addition, the concrete pre-exposed to CO₂ curing produced less expansion than the concrete pre-exposed to moist curing during the subsequent accelerated curing in 60 °C water. This study provides a potential approach to prepare concrete with low-carbon emissions via the accelerated carbonation of steel slag.     

Modification of steel slag powder by mineral admixture and chemical activators to utilize in cement-based materials

Modification of steel slag powder by mineral admixture and chemical activators to utilize in cement-based materials was studied in this work. The results showed that for cement pastes with steel slag alone, the normal consistency water requirement and compressive strength were decreased significantly. Both of the initial setting time and final setting time were also retarded than that of the control sample. When a compound admixture of ground granulated blast furnace slag (GGBFS) -steel slag powder added the compressive strength was evidently improved. Modification of steel slag powder by “Gypsum-type” and “Sodium-type” chemical activators were further studied. Cement paste with the modified compound admixture by 1.5 % calcium sulfate hemihydrate or sodium sulfate, its 28 days compressive strengths could reach to 75.4 and 76.2 MPa, respectively. X-ray diffraction (XRD) patterns showed that the main hydration products mainly included Ca(OH)₂ and ettringite. It indicated that proper mineral admixture and chemical activators had a positive effect regarding early hydration of steel slag powder, and enhanced forming calcium silicate hydrate(C–S–H) gel and ettringite. This work contributes to understanding of how to sustainably manage wastes and byproduct materials and has the potential to provide several important environmental and economic benefits.     

Carbonation process of alkali-activated slag mortars

This study analyzes the behaviour of waterglass- or NaOH-activated slag mortars after carbonation. The effect of a superplasticizer based on vinyl copolymer and shrinkage reducing polypropylenglycol derivative admixtures on that process was also examined. The same tests were run on cement mortars for reference purposes. The mortars were carbonated in a chamber ensuring CO₂ saturation for four and eight months, after which ages the samples were tested for mechanical strength; mercury porosimetry and mineralogical (XRD, FTIR) and microstructural characterization (SEM/EDX) were also conducted. The results obtained indicate that alkali-activated slag mortars were more intensely and deeply carbonated than Portland cement mortars. Carbonation took place directly on the gel, causing decalcification. When waterglass was the alkaline activator used, carbonation caused a loss of cohesion in the matrix and an important increase in porosity and decrease in mechanical strength. When a NaOH solution was used as the alkali activator, carbonation enhanced mortar compaction and increased mechanical strength. Finally, in waterglass-activated slag mortars, the inclusion of organic admixtures had no effect either on their behaviour after carbonation or the nature of the reaction products.     

循环流化床固硫灰渣低收缩水泥的制备及性能

通过分别使用循环流化床(CFBC)固硫灰、渣代替部分原材料制备低收缩水泥熟料,加入质量分数为10%的石膏即得到CFBC固硫灰、渣低收缩水泥,然后利用X射线衍射、扫描电镜等方法研究水与水泥的质量比(简称水灰比)对CFBC固硫灰渣低收缩水泥水化程度、抗压强度和线性膨胀率的影响。结果表明,随着水灰比的增加,CFBC固硫灰渣低收缩水泥的主要水化产物钙矾石数量增多,未水化的硅酸二钙含量减少,水化程度增大;而该水泥线性膨胀率与水灰比呈正比关系,抗压强度与其呈反比关系;利用固硫灰制备的水泥早期膨胀率随着水化时间而增大,但后期由于石膏量的不足,膨胀率则随着水化时间而减小。     

碱激发锰渣胶凝材料的探索研究

以锰渣为主要研究对象,采用X射线衍射分析、差热分析等测定方法对原材料进行了物性分析,锰渣的主要矿物组成有SiO_2和CaO,属于碱性废渣,当温度低于550℃时其热稳定性较好.通过对复合碱激发剂的探索可知,当水玻璃模数为1.6时,25%水玻璃、2.5%NaOH和1%K_2CO_3复合激发锰渣后,其碱胶凝材料的凝结时间满足浆体的一般工作要求.在该复合激发剂作用下,以10%硅酸盐水泥熟料等量替代锰渣后,制成的碱激发锰渣胶凝材料的力学强度发展符合胶凝材料的一般规律;其水化过程分析表明,随水化龄期的延长,SiO_2被剥蚀解体量增多,生成较多的C-S-H凝胶及少量沸石类结构复杂的物质,强度逐渐提高.     

The hydration properties of pastes containing municipal solid waste incinerator fly ash slag

This study investigated the hydration properties of Type I, Type III and Type V cements, mixed with municipal solid waste incinerator fly ash, to produce slag-blended cement pastes. The setting time of slag-blended cement pastes that contained 40% slag showed significantly retardation the setting time compared to those with a 10% or even a 20% slag replacement. The compressive strength of slag-blended cement paste samples containing 10 and 20% of slag, varied from 95 to 110% that developed by the plain cement pastes at later stages. An increased blend ratio, due to the filling of pores by C-S-H formed during pozzolanic reaction tended to become more pronounced with time. This resulting densification and enhanced later strength was caused by the shifting of the gel pores. It was found that the degree of hydration was slow in early stages, but it increased with increasing curing time. The results indicated that it is feasible to use MSWI fly ash slag to replace up to 20% of the material with three types of ordinary Portland cement.