水泥-粉煤灰-石灰石粉复合浆体的流变性能

采用Rheolab QC型旋转黏度计研究了水泥–粉煤灰–石灰石粉复合浆体的流变性能,分析了不同粉体含量以及石灰石粉颗粒粒径对复合浆体屈服应力、塑性黏度以及触变性的影响。结果表明:复合浆体中石灰石粉掺量增大或颗粒粒径减小,浆体屈服应力、塑性黏度和触变性均增大;随剪切速率增大,水泥–粉煤灰–石灰石粉复合浆体发生显著的剪切稀化现象,随后塑性黏度渐趋稳定,掺入石灰石粉后,提高了浆体由剪切稀化向塑性黏度逐渐稳定时需要的剪切速率;在水泥–粉煤灰体系浆体中掺入质量分数为20%～40%石灰石粉能够显著改善浆体的流变性能,提高浆体的稳定性。     

硅酸盐水泥—阳离子乳化沥青浆体的流变模型

硅酸盐水泥--乳化沥青浆体的流变性决定了水泥乳化沥青砂浆的施工性能,并影响高速铁路板式无砟轨道砂浆充填层的施工质量和耐久性。采用P·II52.5R硅酸盐水泥和阳离子乳化沥青制备了不同配合比的硅酸盐水泥--阳离子乳化沥青(PC-CEA)浆体。在25℃用同轴旋转流变仪测量各种PC-CEA浆体的流变曲线。用不同流变模型拟合实测的PC-CEA浆体的剪切应力和剪切应变数据,分析了其流变行为和组成配比的关系。结果表明:PC-CEA浆体具有屈服应力和触变性,并主要呈剪切变稀行为;依据拟合良好性,Herschel-Bulkley模型最适合表征PC-CEA浆体流变性;由该模型拟合获得的PC-CEA浆体的屈服应力和稠度系数随浆体中水泥占浆体总体积分数(水泥体积分数)增加而增加,随着浆体中水泥和沥青颗粒的体积分数(固体体积分数)的减小而减小;当固体体积分数≤40%时,PC-CEA浆体出现剪切增稠行为。     

水泥-白云石粉浆体流变性能研究

试验采用旋转黏度计测定了水泥-白云石粉浆体剪切应力和塑性黏度随剪切速率变化的规律,对所测浆体T-γ曲线采用Bingham流体模型进行拟合,得到浆体屈服应力和塑性黏度,采用Power Law流体模型拟合出浆体的流变指数,并用触变环面积表征浆体的触变性.研究结果表明:在0 ～ 30％掺量范围内,随白云石粉掺量的增大,水泥浆体的屈服应力、塑性黏度和触变性均逐渐增加;白云石粉细度对浆体屈服应力和塑性黏度影响较小.     

掺混城市污泥对神木煤成浆特性的影响

将城市污泥以不同质量比掺入神木煤制备污泥煤浆，利用安东帕C-LTD80/QC型旋转流变仪考察了污泥掺混质量比(α)对污泥煤浆的最大成浆浓度、流变性、触变性和稳定性等成浆特性的影响。借助FTIR和SEM表征煤、污泥及水煤浆，探讨掺混城市污泥影响神木煤成浆性能机制。结果表明：水煤浆及污泥煤浆流变特性均符合幂定律模型τ=Kγⁿ,随着α的增大，污泥煤浆表观黏度增大，最大成浆浓度降低，浆体流变性指数n减小，剪切稀化特性明显，浆体更加趋向于假塑性流体；同时，α的增大也会使得浆体触变环面积增大，进一步导致浆体触变性增强；此外，加入污泥制备的污泥煤浆，浆体产生沉淀时间明显延长，其析水率与相同成浆浓度下的水煤浆的析水率相比明显降低，说明适当的污泥掺混量有利于改善浆体的稳定性。通过FTIR及SEM分析可知，污泥填充了煤粉颗粒之间的空隙，在浆体内部形成较强的空间结构，这种作用是导致掺混污泥后浆体的表观黏度增大、最大成浆浓度降低、稳定性提高的主要原因。在尽可能提高污泥掺混比例的条件下，当α为0.12,污泥煤浆的最大成浆浓度为60.42%时，浆体的成浆性能良好，满足工业要求。     

炭粉对萘系减水剂与水泥相容性影响的研究

以炭粉模拟研究萘系减水剂与水泥相容性的影响,测定了炭粉对水泥净浆流动性能、流变性能及吸附性能的影响,同时提出了炭粉对萘系减水剂的吸附模型。结果表明:(1)当炭粉含量为5%时,掺萘系减水剂的水泥浆体相容性不良;(2)炭粉可增大水泥净浆的粘度及屈服应力;(3)炭粉可使浆体由触变性逐渐转变为反触变性;(4)炭粉对萘系减水剂的吸附既有单分子层的化学吸附,也有单分子层或多分子层的物理吸附,符合Freundlich吸附模型。     

石膏掺量对高阿利特水泥防腐抗渗性能的影响研究

研究了石膏掺量对高阿利特水泥抗海水侵蚀和抗渗性能的影响,并与普通水泥进行了比较。利用XRD、SEM—EDS等测试方法对水泥水化产物的物相组成和形貌进行分析、观察;用压汞法对水泥硬化浆体的孔结构进行了分析。结果表明,石膏掺量对高阿利特水泥硬化浆体的致密性有较大影响,进而影响水泥砂浆的抗海水侵蚀性能,石膏的适宜掺量为5％,在此掺量下高阿利特水泥的抗蚀系数达1．01,而普通水泥的抗蚀系数仅为0．87,高阿利特水泥的有害孔较少,总孔隙率较低,抗渗性能得到较大改善。     

UHPC浆体的工作性和流变性与颗粒膜层厚度的关系

建立超高性能混凝土(UHPC)浆体的工作性和流变性之间的关系可从理论上研究其工作性变化规律。本文以颗粒膜层厚度为UHPC浆体的工作性的综合衡量指标,设计了正交试验,研究水胶比、超细粉煤灰替代率和硅灰掺量对UHPC浆体的工作性与流变性的影响。根据流动度和流变性测试结果,分析了水胶比和超细粉煤灰替代率的共同作用对UHPC浆体的工作性与流变性的影响,探究了UHPC的净浆与砂浆的工作性关系,基于浆膜层厚度给出了UHPC砂浆的工作性与流变性的关系式。研究结果表明:水胶比是UHPC浆体的工作性与流变性的最主要影响因素,水胶比、超细粉煤灰替代率和硅灰掺量提高均造成UHPC浆体的颗粒表面膜层厚度增大;水胶比和超细粉煤灰替代率的共同作用下,UHPC浆体的流动度和黏度系数具有相关性。     

不同外加剂对水泥基灌浆材料流变性能的影响

采用Brookfield公司生产的R/S-SST型流变仪,在固定灌浆料水灰比与减水剂掺量条件下,分别研究了生物胶、缓凝剂、消泡剂在恒定剪切速率与变化剪切速率下对灌浆料料浆表观粘度的影响,同时还对料浆的触变性进行了研究.结果表明,不同条件下测得的流变曲线均符合Herschel-bulkey(n<1)的流体模型,即浆体表征为时变性非牛顿流体.剪切速率不同,外加剂品种及掺量不同,其粘度随时间的变化亦不一样.生物胶、缓凝剂对料浆的触变性影响与消泡剂对料浆触变性影响不同,前两者表现为减小料浆的触变性,而后者增大料浆的触变性.     

煤气化废水成浆特性及添加剂的适配性

利用煤气化过程中洗气工艺段产生的有机废水（简称“洗气水”）、实验室中的去离子水分别与神华煤制备水煤浆,并进行了成浆性、流变性、稳定性以及添加剂适配性的实验。研究结果表明,洗气水水煤浆的定黏浓度能达到61%以上,比去离子水水煤浆高1%～2%,假塑性特征也更加明显;比较不同添加剂的成浆效果,发现亚甲基双萘磺酸钠和萘系添加剂的效果较好;水煤浆的稳定性与添加剂的结构有关,木质素磺酸钠由于能形成稳定的络合结构因此浆体具有较好的稳定性;与去离子水水煤浆相比,洗气水水煤浆的触变性和稳定性有所降低。利用洗气水制备水煤浆,不仅实现了废水的资源化、无害化利用,而且能提高浆体的成浆浓度,具有较好的工业应用前景。     

水焦浆添加剂最佳用量的实验研究

为了优化石油焦的成浆效果并确定水焦浆添加剂的最佳用量,实验研究了某石油焦在分别加入3种不同类型添加剂后的成浆特性,考察了添加剂用量对水焦浆成浆性、流变性和稳定性的影响。结果表明:当添加剂用量为石油焦干基质量的0.8%时,3种添加剂下石油焦均能获得较好的成浆性;NSM(亚甲基萘磺酸钠-苯乙烯磺酸钠-马来酸钠)和NC(亚甲基萘磺酸盐甲醛缩合物)添加剂使水焦浆呈胀流性,而LS(木质素磺酸盐)添加剂使水焦浆呈假塑性,添加剂用量的多少对水焦浆流变性的影响不大;当添加剂用量为石油焦干基质量的0.6%—0.8%之间时,水焦浆具有相对较好的稳定性。因此,添加剂用量为石油焦干基质量的0.8%时,水焦浆的综合成浆品质最优。     

The influence of surface-modified graphites on the rheological pattern of alumina-carbon cementitious refractory castable matrix

The present contribution focused mainly on the fundamental understanding of the influence of surface-modified graphite on rheology of the matrix of a castable slurry in comparison to the same containing the uncoated one. A special observation on the rheology of a graphite-free matrix of similar high alumina castable has been described. The change in rheological behavior due to the presence of other microfine constituents has also been noticed with a particular attention to the refractory cement bond. The variation in viscosity and shear stresses with shear rate of castable matrices containing as-received and surface-modified graphites has been compared. The ‘ball-in-hand’ consistency test of respective castables had also been differentiated. The effect of coated and uncoated graphites on the loss and storage moduli of the respective suspensions has been explored. Zeta potential values of individual constituents as well as the slurries have also been measured and correlated with the flow characteristics of castable matrices. The X-ray diffraction (XRD), SEM (scanning electron microscope) and EDS (energy dispersive spectroscopy) studies of the coated graphite have been observed to substantiate the flow pattern of the slurry. The physical properties of refractory castables at different temperatures have been estimated to supplement the rheological pattern.     

eρ-Al2O3和铝酸盐水泥对磷酸铝结合高铝浇注料性能的影响

以优质高铝矾土或板状刚玉、烧结α-Al2O3微粉为主要原料,采用磷酸铝和ρ-Al2O3为固化剂,研究铝酸盐水泥和ρ-Al2O3对磷酸盐结合高铝质浇注料性能的影响。结果表明,单独采用ρ-Al2O3为固化剂其硬化效果差,且随ρ-Al2O3加入量的增大,施工性能降低;单独采用铝酸盐水泥不利于浇注料的高温性能;而采用ρ-Al2O3和铝酸盐水泥复合固化硬化效果好,且浇注料综合性能比单独使用ρ-Al2O3或铝酸盐水泥均有显著提高。     

新型隔热耐磨衬里浇注料的研制

为了提高现有隔热耐磨衬里浇注料的理化性能,改善产品的施工性能,选用页岩陶粒和原皮陶粒搭配作骨料,选用水泥作结合剂,选择六偏磷酸钠和萘系减水剂作外加剂,并加入一定量的混合细粉和硅灰,通过确定颗粒临界粒度和级配,研制了新型隔热耐磨衬里浇注料.结果发现颗粒临界粒度为8 mm,骨料和细粉的基本配比为4951,高铝水泥的加入量为35%,硅灰的加入量为4%,并合理选配外加剂,制备出的新型隔热耐磨衬里浇注料性能优良.     

Rheology of latex-modified grouts

The rheology of grouts containing latex was investigated. The two latex additives used were carboxylated styrene-butadiene and acrylic. The influences of superplasticizer, fly ash, and blast furnace slag on the rheology of latex-modified grouts were addressed. Shear stress-shear rate curves were determined for a variety of mix proportions. The time-dependent behaviour of selected grouts was also studied. It was determined that the yield stress and apparent viscosity are influenced by latex content and that the grouts are shear thinning at low water/cement ratios. Latex imparts stability and thixotropy in grouts. Partial replacement of cement with either fly ash or slag diminishes the effect of latex on rheology.     

Heat resistance and thermomechanical behaviour of ultralow and zero cement castables

Abstract

Knowledge of relative heat resistance as well as thermo-mechanical behaviour of refractory castables is very important for their use as linings in high temperature furnaces and refining vessels in the metallurgical, cement, and petrochemical industries. The present work aims at studying these properties for different types of refractory castable. Two classes of castable were prepared, namely ultralow and zero cement, containing either high alumina cement or hydratable alumina as bonding agent. For each class, two different castable systems were prepared, one containing an alumina-silica mixture in its matrix and the other containing magnesia-alumina. In all castables studied, calcined alumina was used as aggregate. The prepared castable samples were subjected to firing temperatures up to 1500°C. Relative heat resistance, bending strength before and after thermal cycling, hot modulus of rupture, and creep deformation were measured according to international standard specifications. It was concluded that a limited content of cement (ultralow cement castables) is beneficial with the magnesia-alumina mix in the matrix owing to the formation of calcium hexaluminate-magnesium aluminate-corundum (matrix advantage system) that results in excellent relative heat resistance as well as thermome-chanical properties. Zero cement castables on the other hand are recommended for use with the alumina-silica mixture, since the absence of cement improves the chances of mullite formation without glassy phases, thereby enhancing the properties of such refractory castables.     

新拌活性粉末混凝土流变性能研究

研究了硅酸盐水泥、硅灰、粉煤灰或(和)石英粉等配制的活性粉末混凝土(RPC)的流变性能,包括新拌RPC的流变类型、触变性、水胶比(W／C)、掺合料种类及掺量、减水剂等对新拌RPC的流变学特征的影响。     

电炉盖用钢纤维增强浇注料的研制

以优质矾土熟料和烧结刚玉为骨科及掺合料，加入一定比例的钢纤维，配制成热震稳定性好，耐侵蚀的钢纤维增强高铝浇注料。     

Application of New Calcium Aluminate Cement CA-670 in Low Cement Castables

A new calcium aluminate cement CA-670 was studied in the system of tabular alumina,white fused alumina( WFA),and bauxite based low cement castables.The flow ability,strength development,and hot strength( HMOR) were investigated. Different types of additives were used for the CA-670 bonded castables. The results show CA-670 provides a good workability for each type of castables. CA-670 displays a good compatibility with different types of additives. Testing on different batches of CA-670 shows good reproducible properties in each castable,which manifests good consistency and reliability of CA-670.     

低水泥自流耐火浇注料

简述了加有ＳｉＯ２、Ａｌ２Ｏ３微粉的高铝质低水泥自流浇注料中所涉及的化学过程。研究了ＳｉＯ２、Ａｌ２Ｏ３微粉、高铝水泥含量、加水量对低水泥耐火浇注料物理性能的影响。讨论了分散剂、促凝剂、延迟硬化剂在低水泥自流耐火浇注料中的作用。     

Effects of different additives on properties of magnesium aluminate Spinel–Periclase castable

Bauxite- and alumina-based spinels were employed as refractory aggregates, and sintered magnesia fine powder, calcium aluminate cement, microsilica, and activated α-Al₂O₃ were utilized as matrices. The effects of alumina powder, analytically pure zinc oxide, and analytically pure zirconia on the properties of magnesium aluminate spinel–periclase castables were studied. The results demonstrated that the addition of the three additives promoted the sintering of magnesium aluminate spinel–periclase castables. Simultaneously, the three additives significantly improved the high-temperature properties of the samples. The thermal shock resistance of the alumina powder sample increased by 200%, that of the pristine zinc oxide sample by 75%, and that of the zirconia sample by 125%. The additives effectively improved the thermal shock resistance of the magnesium aluminate spinel–periclase castable. In addition, the slag resistance depths of the samples with alumina powder and zirconia were 41% lower than that of the sample without additives, which significantly improved the slag resistance of the magnesium aluminate spinel–periclase castable.