碱激发碳酸盐矿-矿渣复合灌浆材料流变性能的研究

采用R/S-SST流变仪测定了不同配方的碱激发碳酸盐矿-矿渣复合灌浆材料浆液静置不同时间的流变曲线。探讨了硅酸钠溶液模数和浓度、矿渣及缓凝剂掺量对浆液流变性能的影响。结果表明：碱激发碳酸盐矿-矿渣复合灌浆材料为宾汉姆流体,随硅酸钠溶液浓度增大、模数减小、矿渣掺量增加,浆液的屈服值和塑性粘度增大;掺加缓凝剂后,浆液的流变性能显著改善。     

特种绿色环保水泥的研究

研究激发剂—矿渣粉体混和料体系制备新型的胶凝材料的可行性。通过试验掺入适宜浓度的激发剂可使矿渣粉体混和料达到32.5、42.5水泥等级的要求,用这种胶凝材料可以配制不同强度等级的砂浆或混凝土。     

碱渣胶凝材料及其混凝土性能试验研究

碱渣胶凝材料及其混凝土性能试验研究李燕，刘凯，李艳萍东北勘测设计研究院科学研究院１前言矿渣是高炉炼铁过程中排出的非金属矿物溶渣，矿渣磨细后经碱性溶液激发活性形成胶凝材料，与碎石或卵石、砂及少量外加剂混合，能配制出无水泥熟料的混凝土，这种混凝土具有孔结...     

碱激发矿渣-赤泥新型低碳透水混凝土性能研究

以粒化高炉矿渣与拜耳法赤泥两种工业固废作为胶凝材料,硅酸钠溶液作为碱激发剂,石灰岩碎石作为粗骨料,制备透水混凝土,研究了设计孔隙率、水胶比与骨料粒径对透水混凝土强度与透水性能的影响。结果表明：随设计孔隙率增大,试样的强度逐渐减小,但透水性能逐渐增强。最优水胶比受设计孔隙率和骨料粒径的影响,当透水混凝土设计孔隙率为15%、骨料粒径为4.75～9.50 mm时,最优水胶比为0.36,其强度较高且具有良好的透水性能。碱矿渣-赤泥透水混凝土的力学与透水性能均优于水泥透水混凝土,符合低碳绿色的发展理念。     

不同养护方式下锂渣反应程度和微观形貌

锂渣反应程度对锂渣混凝土性能的影响较大,为此,采用盐酸溶解法测试水泥-锂渣浆体中锂渣的反应程度,通过电镜扫描和能谱研究水泥-锂渣砂浆的孔结构和水化产物,并探讨养护条件(标准养护、热养护、碱激发、碱激发和热养护)对上述指标的影响。结果表明:锂渣复合胶凝材料中锂渣的反应程度随龄期的延长而增大,养护条件的改变也能促进锂渣反应程度的增长,相对而言,碱激发和热养护的促进作用＞碱激发＞热养护＞标准养护;同时,锂渣的掺入或养护条件的改变都会改变砂浆的孔径分布,达到细化孔结构和改变浆体中水化产物含量的目的。因此,养护条件的改变能促进锂渣反应程度的提高和细化浆体的微观结构。     

碱激发高钛矿渣-水泥基胶凝体系水化活性研究

采用丽江42.5中热水泥,攀钢集团水淬高钛矿渣,对Ca(OH)2、NaOH及Na2CO3等碱激发剂激发高钛矿渣的早期活性进行了研究,并探讨了高钛矿渣的化学活化技术及其活化机理,以期为高钛矿渣的综合利用提供理论支持。结果表明：激发剂的掺量不宜过大,最优掺量范围为4%~6%;Ca2+对掺高钛矿渣复合胶凝体系的激发效果较好,且在OH-存在的条件下,早期激发效果更佳。机理分析表明,Ca2+和OH-对高钛矿渣活性的激发,主要是依靠OH-的极化作用,形成具有胶凝作用的水化CaSiO4等产物,且当溶液中Ca2+和SO2+4共存时,能较大程度地激发高钛矿渣的潜在活性。     

水泥－粉煤灰－矿渣粉三元胶凝体系体积稳定性的研究

研究了不同胶凝材料体系水泥浆体的体积收缩变形特性。试验结果表明：水泥品种与细度是影响硬化浆体体积稳定性的主要因素,水泥细度越大,硬化浆体的体积稳定性越差,低热（高贝利特）硅酸盐水泥浆体的体积稳定性优于中热硅酸盐水泥;矿物掺和料的掺入使得胶凝材料的体积稳定性变得复杂,优质的矿物掺和料能够降低硬化浆体的收缩;水泥－粉煤灰二元胶凝体系的体积稳定性优于水泥－粉煤灰－矿渣粉三元胶凝体系。     

废弃玻璃粉在混凝土中的应用机理及ASR风险

废弃材料广泛应用于土木工程领域,废弃玻璃粉用作混凝土辅助胶凝材料符合我国建材的可持续发展要求。在大量文献调研的基础上,分析废弃玻璃在混凝土中应用的可行性。结果表明,玻璃在复合胶凝材料水化硬化过程中不仅具有一些特殊的作用机理,还存在ASR风险。由于含有大量的无定性二氧化硅,玻璃用作骨料时容易引发碱-骨料反应,但磨细成粉料可用作活性辅助胶凝材料。因此,本文提出将废弃玻璃粉磨成粉体材料用作混凝土辅助胶凝材料,并探讨废弃玻璃粉在复合胶凝材料水化硬化过程中的作用机理及ASR风险。将废弃玻璃磨细成粉料,既可以解决玻璃骨料的碱-骨料反应问题,还能发挥其火山灰作用,改善混凝土的性能。     

砂岩骨料在斯登沃代(Stung Atay)水电站大坝混凝土中的应用

斯登沃代水电站开展的砂岩骨料大坝混凝土应用研究成果表明:工程区域料场砂岩骨料具有吸水率大、微粒含量较多等特点,用其配制的混凝土存在用水量大、胶凝材料多和混凝土干缩、湿胀变形较大等缺陷。因此,在工程使用硅酸盐水泥进行混凝土配合比设计的同时,建议采用减水率更高的缓凝高效减水剂;同时,应加大粉煤灰掺量,以达到抑制骨料碱硅酸反应,减少混凝土胶凝材料用量,降低混凝土水化热温升,减少混凝土的收缩变形,提高混凝土的抗裂性能和耐久性能。     

掺碱激发剂粉煤灰-水泥胶砂强度性能试验研究

在粉煤灰-水泥中掺入碱激发剂不但可以改善粉煤灰活性,提高粉煤灰-水泥胶凝材料的性能,而且还保护环境,可以带来显著的经济效益。制作掺入不同碱激发剂的粉煤灰-水泥试块,测定在不同碱掺量下的试块的胶砂强度,进而评价碱激发剂对粉煤灰活性的激发效果。通过试验可知,掺适量碱均可提高粉煤灰活性;不同龄期NaOH的最佳掺量不一致,3 d时NaOH最佳掺量为粉煤灰质量的5%,而28 d时为6%;不同龄期粉煤灰的最佳CaO掺量基本一致,均为粉煤灰质量的8%;NaOH早期强度发展较快,后期水玻璃发展较快;CaO比NaOH激发效果好。     

矿渣对高镁水泥硬化浆体膨胀特性及微观结构的影响

MgO可用于补偿大体积混凝土的收缩,大坝混凝土中也已有应用高镁水泥的先例。为充分利用高镁水泥的膨胀特性,避免其膨胀量过大,本文研究了矿渣掺量和细度对其膨胀特性的影响,并表征了硬化浆体的孔结构与微观形貌。结果表明,掺入矿渣可以有效降低高镁水泥硬化浆体的膨胀率。矿渣的掺量越高,硬化浆体膨胀率越低。矿渣的细度越细,抑制硬化浆体膨胀的作用越明显,中位径为4．81μm时,硬化浆体膨胀率显著降低。矿渣抑制高镁水泥硬化浆体膨胀的作用,主要源于矿渣掺入之后所产生的“物理稀释作用”和“二次水化效应”。“物理稀释效应”降低了硬化浆体中方镁石总量;“二次水化效应”填充了硬化浆体空隙,使硬化浆体孔径细化,毛细孔缓冲和释放硬化浆体膨胀应力。     

Treatment of spent brine from a nitrate exchange process using combined biological denitrification and sulfate precipitation.

A combined biological denitrification and sulfate precipitation process was developed to treat and reuse the spent brine produced by a nitrate exchange system. Although the spent brine contained a relatively high salt concentration, more than 80% of NO3(-)-N fed into the denitrification reactors was removed at a nitrate-N loading rate of 2.2 g NO3(-)-N/l x day, regardless of the presence or absence of sulfate up to 8,000 mg/l. Sulfate present in the spent brine was successfully removed by the addition of BaCl2 and the settling velocity of BaSO4 suspension was remarkably enhanced by FeCl3 coagulation. Since most of the chloride consumed in regenerating the exhausted resins was replaced during chemical treatment with BaCl2 and FeCl3, it was possible to reuse the treated spent brine as a regenerant after compensating for the small amount of unreplaced NaCl.     

Effect of magnesia on properties and microstructure of alkali-activated slag cement

The effect of magnesia burnt at 800-950 ℃ on the properties, especiallythe shrinkage, of alkali-activated slag cement (AASC) was experimentally studied. Experimental results show that, although adding 4%-8% lightly-burnt magnesia may shorten the setting time and slightly reduce the compressive strength of AASC, it can remarkably reduce the shrinkage of AASC. The results also show that the setting time of AASC with a certain amount of magnesia increases with the burning temperature, and that the flexural and...     

Influence of compost characteristics on heavy metal sorption from synthetic stormwater.

This paper has the aim to assess the ability of garden derived compost to remove dissolved heavy metal contaminants typically found in stormwater. Compost was found to have excellent chemical and physical properties for the sorption of dissolved metal ions (Cu2+, Pb2+ and Zn2+). Batch sorption data were used to determine the sorption efficiency of Cu (93%), Zn (88%) and Pb (97%) by compost. The relative sorption affinity of these metals by compost is found to be in the order of Pb2+ > Cu2+ Zn2+. The effect of different particle size fractions of compost upon the sorption of Cu was also investigated. Sorption conformed to the linear form of the Freundlich isotherm and can be considered favourable because the sorption intensity values obtained in this study are between 0.1 and 1. Compost with a smaller particle size fraction has larger surface areas and greater sorption than the larger particle size fraction. Compost derived from garden waste is efficient for removal of heavy metals from wastewater or treating water for industries.     

三种不同掺合料对水泥浆体界面性能的影响

为了分析新型矿物掺合料对高性能混凝土界面区微结构的影响,采用层析方法进行研究。通过分别掺入不同量的钢渣、矿渣及粉煤灰,定量分析了硅酸盐水泥浆体 － 集料界面区氢氧化钙取向指数和界面区厚度的变化。试验结果表明: ( 1) 掺入 30% 矿渣粉后,界面处 Ca( OH) 2 取向比纯水泥明显下降,几乎没有取向,界面区厚度比纯水泥浆体的界面略低。掺 30% 粉煤灰后,界面处 Ca( OH) 2取向度介于纯水泥与掺矿渣粉水泥界面取向度之间,但过渡区厚度明显减小。加入 30% 的钢渣后,水泥浆体与集料的界面晶体取向明显增加,界面区厚度也明显增加; ( 2) 随钢渣比表面积增加,水泥浆体与集料界面的 Ca( OH) 2 晶体取向度及界面厚度都有不同程度的减小。当钢渣比表面积增加至600 m2 /kg 时,含钢渣浆体界面的性能已优于纯水泥浆体界面的性能; ( 3) 钢渣与矿渣粉或粉煤灰二元复合只能改善浆体与集料界面区某一方面的性能,但钢渣与矿渣粉、粉煤灰三元复合可明显改善浆体与集料界面的综合性能。研究结果可为高性能混凝土整体性能研究及设计提供参考意见。     

镍铁渣粉水泥土的固化机理试验研究

为了研究镍铁渣粉水泥土的固化机理,从滨海区域工程实际出发,将镍铁渣粉等量替代水泥质量掺入到水泥中,结合ＸＲＤ试验、ＳＥＭ试验和压汞试验对镍铁渣粉水泥土的固化机理进行分析,从而实现以宏观和微观相结合的方式来考察其在海洋环境下的强度及抗渗性能。结果表明:水泥石中掺与镍铁渣粉,其物相种类不发生改变,主要为Ｃａ（ＯＨ）２、Ｃ３Ｓ、Ｃ２Ｓ、ＣａＣＯ３和ＳｉＯ２这五种物相;镍铁渣粉水泥土的孔径在７ｄ和２８ｄ时走势及大小变化不显著,而６０ｄ龄期以后,总孔隙体积和最可几孔径逐渐减小;随着龄期的增长,镍铁渣粉水泥土中的水泥水化产物增加,其孔隙逐渐消失,镍铁渣粉开始发挥作用并且其微观结构整体性愈发增强。     

Zinc, lead and cadmium speciation in Dnieper water-bodies

Data on the concentrations and movements of Zn, Pb and Cd in Dnieper reservoirs and the Dnieper‐Bug estuary are considered. There is a clear trend of increasing concentrations, often two‐ to fourfold, of these materials from the 1960s to the end of the 1980s. Large increases may be explained as the result of increased human impact on the water‐bodies and also because of reduced water discharge in the Dnieper River (discharge has been reduced by nearly 10 km³ in recent years). At present, the average concentrations of Zn, Pb and Cd in Dnieper water‐bodies are 35.0–50.0, 15.0–18.0 and 0.5–1.8 μg L^–1, respectively. Anodic stripping voltammetry, membrane filtration, ion‐exchange and gel permeation chromatography on neutral sephadexes were methods used for analysis. The influence of adsorption and complexation processes on the mobility of Zn, Pb and Cd, and the ratio of their forms were compared. Ratios of free metal ions to ions bound in complexes with natural organic ligands were studied. The binding of metals in complexes with dissolved organic matter (DOM), or their adsorption onto suspended particles, were major processes reducing the concentration of free ions in their most toxic form. The percentage of Zn, Pb, and Cd free ions in the total balance of dissolved forms was no more than 3.6–4.8, 0.2–0.6 and 7.2–9.5%, respectively. The molecular‐weight distribution of organic metal complexes and their chemical nature, as well as the potential for complexing of DOM were investigated. Most Zn, Pb and Cd was found as complex compounds with DOM of different chemical natures and molecular weights. Humic substances, particularly fulvic acids, played a major role in the migration of the metals. These ligands bind from 40 to 80% of metals in the composition of organic complexes. Metal complex compounds of relatively low molecular weight (< 5000 Da) predominated in organic complexes of Zn (38–50%), Pb (38–52%) and Cd (22–47%). The role of inorganic ligands in complexation in surface waters was less important.