Study of the effect of type of high-alumina cement on the properties of heat-resistant concrete with a composite deflocculant

Differences are demonstrated in hydration of high-alumina cements, produced in the Gor’ka Plant (Poland), in the presence of both individual and composite deflocculants. Properties are provided for medium-cement heat-resistant concrete with a composite deflocculant in relation to cement type.     

Effect of composite deflocculant on the properties of medium-cement heat-resistant concrete

Comparative analysis is provided for the properties of medium-cement concrete based on mullite filler in relation to different type of deflocculant. The effect of different deflocculants on concrete structure formation, hydration, rheology, strength and heat resistance is discussed. It is proposed that in concrete with a composite deflocculant it is possible to form nano-structures as a result of which there is a considerable increase in concrete strength after drying at 110°C.     

Effect of the quality of microsilica on the flow properties of cement slurry and characteristics of low-cement refractory concrete on a chamotte filler

The effect of impurity content in different grades of microsilica (MS) on the physicomechanical characteristics of a low-cement refractory concrete based on a chamotte filler is considered. The high content of impurities in MS degrades the flow properties of cement slurry and the respective concrete slurry. It is shown that as ambient temperature grows to 30°C, the impurities in MS increase the cement slurry thickness and impede the placement of refractory concrete in summer period. If low-quality MS is used in concrete, an increased crack formation is observed under the cyclic high-temperature effect. __________ Translated from Novye Ogneupory, No. 5, pp. 41–46, May, 2007.     

Effect of temperature on the curing of medium-cement refractory concrete with a composite deflocculant

Results are presented from studies of the properties of medium-cement refractory concrete with a composite deflocculant (the ratio of sodium tripolyphosphate to polycarboxylate ether Castament FS-20 in the deflocculant was 2/1). The properties are examined as a function of the curing temperature (+10, +20, and +30°C) and the choice of cement (Gorkal 40, Gorkal 70). The effect of curing temperature on the rheology of the paste and the strength of the concrete is also discussed.     

一种低黏度混凝土裂缝修复剂的制备及应用研究

压注胶是一种用于恢复混凝土构件的整体性和部分强度的裂缝修复剂,主要由低黏度改性EP(环氧树脂)胶粘剂配制而成。根据修复剂自身黏度的不同分别对应修复不同宽度的细缝。研究结果表明:自制X1改性酰胺基固化剂,可使裂缝修复剂的性能[如初始混合黏度(25℃)为130 mPa·s、适用期(30℃)约35 min、压缩强度为61 MPa和拉伸剪切强度为19.6 MPa等]满足GB 50728—2011标准中对低黏度裂缝修复剂的强度指标要求和工艺指标要求;该修复剂可用于各类混凝土裂缝的修复,特别适用于动荷载疲劳裂缝的修复。     

商砼洗车废渣在水泥生产中的应用

0引言 生产建设过程中产生的建筑垃圾不仅破坏了城市的生态环境,并且占据和浪费了城市宝贵的空间资源.以商砼洗车废渣为例,根据数据显示:每生产1 m3混凝土,会产生0.03 t的废水废渣;我国每年产出超过15亿m3混凝土,对应产生的废水废渣会达到0.5亿t[1].目前国内对于混凝土废水、废渣处理方式大都针对于废水部分的回收...     

A study of the applicability of waste catalyst in heat-resistant concrete

The authors describe the results of studying medium-cement heat-resistant concrete with an additive of waste catalyst (WC) that is generated at oil-processing plants and compare them with traditional microsilica and reactive alumina additives. Certain specifics of reactions between aluminate cement Gorkal-40 and the WC are identified, which accelerate the setting and hardening of concrete. The WC additive facilitates the formation of anorthite in the concrete matrix, which has a positive effect on the thermal resistance of heat-resistant concrete. __________ Translated from Novye Ogneupory, No. 8, pp. 58–62, August, 2006.     

从混凝土的早期开裂讨论水泥品质指标的调整

混凝土的早期开裂主要是由于混凝土失水所产生的干燥收缩、水泥水化所产生的混凝土自收缩以及水泥水化热所产生的温度应变所引起。采用低碱低C3A低水化热的水泥、在混凝土生产中掺入比水泥细的矿物掺合料、在混凝土浇注后采取保湿保温养护等措施可减少或避免混凝土的早期开裂。高强、早强但1d强度适中,低碱、低C3A、低水化热,用粒度小于3μm的混合材替代水泥中的熟料<3μm的颗粒等是改善水泥抗裂性的好途径。     

不同生产工艺的水泥配制混凝土的性能研究

对比研究了不同工艺条件生产的P·II42.5R水泥与外加剂的相容性、不同水灰比条件下的胶砂强度、标准砂浆在不同养护条件下的干缩性能,以及配制相同工作性能与强度等级的混凝土时配合比与干缩性能的差异。结果表明,水泥与外加剂的相容性越好,胶砂强度越高,则配制相同工作性能与强度等级的混凝土时水泥与外加剂用量可以越少。本试验条件下,配制相同工作性能与强度等级的混凝土时,立窑水泥的总胶凝材料用量最大,从而导致立窑水泥配制的混凝土干缩最大。     

2万吨水泥钢板库倒塌的事故分析

0 引言 由于水泥钢板库尚属新装备和新工艺,目前还没有成熟的规范标准.特别是设计、选材和焊接施工中的失误,导致水泥钢板库产生一些质量问题,甚至在吉林、湖南和内蒙古等地出现了钢板库倒塌事故,国外也有钢板库出现倒塌的事故.文中对北方某水泥生产企业4座2万t水泥钢板库的倒塌原因,从库体Q235B材料的选用、结构设计以及施工中焊接工艺和焊缝质量方面进行了细致的分析,并做了大量的检测和试验.为水泥钢板库的推广应用找出合理的设计和施工方案,避免质量事故的再次发生.     

高碱水泥利用的研究

用高碱熟料、沸石和硅灰配制水泥,进行了抑制碱－集料反应试验,测定了水泥的可溶性碱量与有效碱量,检测了水泥及混凝土的性能。结果显示,有沸石和硅灰作为水泥的混合材,在不影响水泥及混凝土性能的情况下,利用高碱熟料生产具有抑制碱－集料反庆性能的水泥是可行的。     

微膨胀型中热水泥在三峡二阶段工程砼中的应用

三峡二阶段工程控制砼用水泥的MgO量为3.5％～5.0％,使砼具有自生体积微膨胀性质,以补偿砼硬化过程中的收缩应力,提高砼抗裂性。试样抽检和观测表明:用MgO量为3.5％～5.0％的微膨胀中热水泥配制砼,具有微膨胀性,最大膨胀量约55μm;一般半年至1年变形趋于稳定。2000年底对大坝砼裂缝调查统计是:无贯穿性裂缝,二类裂缝数为0.171条/万m3、三类裂缝数为0.048条/万m3,均低于三峡工程砼控制二类、三类裂缝数量≤0.5条/万m3要求,为确保三峡工程砼耐久性奠定了基础。     

水泥助磨剂对砼外加剂适应性研究

水泥粉磨过程加入的助磨剂最终要作用于砼的生产过程，而在砼生产中又会加入各种外加剂（如减水剂、调凝剂、增强剂、抗冻剂、防水剂、引气剂等）。为研究助磨剂对砼外加剂的影响程度，我们选择了减水剂、调凝剂、增强剂这常用的三类砼外加剂进行助磨剂对其适应性的研究。试验以传统助磨剂三乙醇胺为对比，选择了非离子型的醇胺类助磨剂A和非醇胺助磨剂NS，含羧基的阴离子型助磨剂YS及复合助磨剂F６、F１１、F１２进行实验。本文就此试验研究作一介绍。１助磨剂对减水剂效果的影响选择减水剂木质素磺酸钙（掺量０．２％），高效减水剂FD…     

盐泥用于生产水泥的研究与探讨

介绍了利用不同的水洗方式,在保证系统水平衡的情况下,降低盐泥中氯离子的含量,将盐泥用于生产水泥,进而实现盐泥的综合利用。实验结果表明:常规水洗、固液比为1∶2且洗涤一两次为最佳水洗方案;洗涤后盐泥生产出的水泥成品,其氯离子含量均能达到水泥技术标准中对氯离子的要求。     

辊压机水泥粉磨技术的研究及应用

辊压机料床粉磨技术是一项先进而成熟的粉磨技术;在辊压机的各种粉磨流程中,由V型静态选粉机和辊压机组成的联合粉磨系统尤其具有优质、高产、低消耗等综合优势。CDG辊压机和静态选粉机的运用实践证实了这个结论。     

高温缓凝剂LY的合成及在低密度水泥浆中的应用

随着石油勘探开发向深部油气层发展,固井长度增加,井底温度升高,需要提高缓凝剂的抗温能力并降低其温敏性。本文首先以AMPS和IA(衣康酸)这两种单体为原料合成共聚物,通过单因素实验法优化合成条件,得出最优合成条件为n(AMPS):n(IA)=50:20,反应温度60℃,引发剂加量1%。再将AMPS/IA共聚物与一种多羟基羧酸盐复配得到新型高温缓凝剂LY,并将该缓凝剂LY应用于低密度水泥浆体系中,通过中、高温条件下的稠化时间对比说明缓凝剂LY对温度的敏感性,实验证实LY的温敏性较小;并通过缓凝剂LY对水泥浆流变性的影响说明缓凝剂的分散性及稳定性,结果证明缓凝剂LY的稳定性较好,并可改善水泥浆的流变性;通过125℃下的高温稠化曲线可知该缓凝剂可抗温度达到125℃,具备高温缓凝剂特性,能够满足固井的要求。再通过XRD谱图分析缓凝剂对低密度水泥石的影响,并最终探讨缓凝机理。     

水泥质量波动对预拌混凝土性能的影响

通过分析广州市3家水泥厂1年时间里的水泥胶砂强度，标准稠度用水量和凝结时间等指标的质量波动情况，探讨了水泥质量波动对预拌混凝土性能的影响，分析结果表明，水泥强度，需求性和凝结时间波动对混凝土性能的影响较大，而且对不同等级混凝土的影响幅度不大。     

Limestone filler cement in low w/c concrete: A rational use of energy

The effect of limestone filler (up to 20%) on the degree of hydration, the volume of hydration products, and the optimal replacement of limestone filler in cement pastes at different w/cm ratios (0.25-0.50) were investigated by using a quadratic statistical model. The results show an increase in the degree of hydration in very low w/cm ratio paste when the limestone filler content is increased. However, the largest volume of hydration products occurs for high w/cm ratio pastes, for which the available space also increases with the limestone filler content. Finally, for a given cement, the optimum limestone filler content for different w/cm ratios can be obtained by using the gel-space ratio concept.In addition, concrete mixtures (w/cm=0.30 and 0.34) were made to determine the compressive strength. The results have shown that concretes containing limestone filler cements present a small reduction of strength at 28 days improving the hydration of clinker particles in the system. The strength of concrete depends on the gel-space ratio, which takes into account all of the effects produced by limestone filler addition: the increase of the degree of hydration, the dilution, and the increase of the effective w/c ratio.     

少掺量钢渣矿渣水泥的研究

在高掺量矿渣水泥中掺少量可看作低质熟料的钢渣,弥补由于熟料掺量少造成的碱性不足。当混合材的总量为６０％～６５％时,钢渣掺量控制在１５％～２０％左右,只需采用普通外加剂,就能够生产４２５水泥。工业性试验在太钢东山水泥厂进行。     

低活性废渣配制复合水泥及其水化机理研究

以低活性的钢渣、锰渣为主掺合料,辅以适量的石灰石粉为超细填料,与熟料配比后制成复合水泥。当钢渣/锰渣的量40%、石灰石粉10%、熟料及半水石膏50%时达到最优化配比,配制成性能符合PC32.5标准的水泥。研究了掺合料的颗粒形貌及粒径分布对复合水泥强度的影响,通过SEM、XRD分析生态水泥的早期水化程度和产物,揭示矿渣生态水泥的水化特点。