灵寿高岭土原矿在水泥基材料中的应用研究

对河北灵寿县高岭土原矿进行表征分析,包括X射线衍射和热重差热分析,并将其在程序实验炉内煅烧,煅烧温度设为550、650、750和850℃,煅烧时间为1、2和3h以制得活性偏高岭土.利用强度活性指数测试法确定各偏高岭土试样的活性,并分析其作为水泥替代材料的潜力.结果表明煅烧至650℃、3h制得的偏高岭土活性最高,替代20％水泥的砂浆28 d抗压强度可达到纯水泥砂浆强度的90％.     

天然粘土火山灰活性试验研究

研究采用高岭石含量较低的天然粘土.首先,对天然粘土在不同温度、不同恒温时间下进行热处理;其次,采用XRD测试对煅烧后天然粘土开展矿物成分分析,并结合TG-DTA测试进一步确定各矿物的分解温度;再次,分别通过电导率测量(EC)和强度活性指数测试(SAI)对煅烧粘土活性大小以及水泥替代效果进行定量评估;最终,确定获取天然粘土最佳火山灰活性的煅烧温度和恒温时间.实验结果表明,煅烧温度700℃ 并保持3 h恒温的天然粘土具有最佳火山灰活性.当采用最佳火山灰活性的煅烧粘土替代30％ 水泥时,混合砂浆7 d抗压强度达到32.55 MPa,与水泥砂浆相比强度增大了11％.煅烧天然粘土可以提高混合砂浆的抗压强度,是一种潜在的水泥替代材料.     

偏高岭土在水泥基材料中应用的研究进展

对偏高岭土的火山灰活性,煅烧工艺,及其对水泥基材料孔结构,水化过程,力学性能的影响进行了综述.详细总结了偏高岭土改性水泥基材料耐久性能的研究进展,包括抗氯离子渗透性能,抗硫酸盐侵蚀性能,抗碱硅酸反应性能,及改性材料的收缩性能,最后提出了偏高岭土矿物掺合料未来的发展趋势并对应用前景进行了展望.     

偏高岭土改性超高强混凝土的强度构成分析

以偏高岭土、矿粉和粉煤灰为矿物掺合料进行单掺、二元和三元复掺配制偏高岭土改性超高强混凝土。为了研究偏高岭土改性超高强混凝土的抗压强度及其强度构成、矿物掺合料的活性,分别对龄期为3d、28d、56d的混凝土试件进行抗压试验,并利用混凝土火山灰效应数值分析方法,对三种矿物掺合料的活性指数及其火山灰效应强度贡献率、水泥水化反应强度贡献率进行了计算分析。结果表明:28d龄期时,混凝土的抗压强度达到了100MPa,且三元复掺时混凝土的抗压强度最高;三种矿物掺合料中偏高岭土的活性指数最高;依据矿物掺合料的活性指数及其火山灰效应强度贡献率、水泥水化反应强度贡献率,计算出具体贡献的强度值,得出了偏高岭土改性超高强混凝土的强度构成。     

细度和煅烧温度对煤矸石火山灰活性及微观结构的影响

通过化学吸钙量和水泥胶砂力学强度测试,研究了煅烧温度及细度对煅烧煤矸石火山灰活性的影响,并结合X射线衍射、红外光谱、扫描电镜和热重测试,研究了煤矸石不同煅烧温度下矿物组成、化学结构及表面形貌发生的变化。结果表明:细度和煅烧温度都会对煅烧煤矸石火山灰活性产生影响,粒度越细煅烧煤矸石的火山灰活性越大,最佳煅烧温度为800℃左右;500℃煅烧时煤矸石中高岭石开始发生脱羟基反应,其层状结构逐渐被破坏;600~800℃煅烧时高岭石完全转变为多孔无序、非晶结构的偏高岭石;煅烧至1 000℃时偏高岭石转化为晶态的莫来石和方石英,使煅烧煤矸石无序度变差、火山灰活性变弱。     

煅烧煤矸石活性的电化学评价

提出了通过测定煅烧煤矸石在饱和Ca（OH）2溶液中溶解、反应平衡后滤液的电阻,以此评价煅烧煤矸石的火山灰活性的新方法,并测定了4个不同产地煅烧煤矸石的火山灰活性指数Ke,分析了煅烧煤矸石的矿物组成、化学成分对滤液导电性能的影响。结果表明：该方法测得的火山灰活性指数Ke与国标GB/T2487-96提出的标准胶砂强度比具有一定的可比性,能够反映出同一种煤矸石在不同煅烧温度条件下相对活性的高低。该方法快速简便,但材料的化学成分变化对该方法测试结果影响较大。     

纳米偏高岭土在水泥基材料中的应用研究进展

纳米偏高岭土在水泥基材料中的研究和应用还处于初级阶段,但其良好的火山灰活性、晶核作用和微集料填充效应已成为改善水泥基材料性能的一个重要方向.综述了纳米偏高岭土对水泥基材料水化、工作性、力学性能和耐久性的影响,介绍了其对水泥基材料性能的作用机理,分析了当前研究存在的问题,并指出了纳米偏高岭土水泥基材料的发展趋势.     

苯丙乳液改性水泥修补砂浆的制备与性能研究

采用复配技术制备苯丙乳液改性水泥修补砂浆,并进行性能研究.探讨了聚合物乳液、偏高岭土、煅烧膨润土等外加剂对该砂浆物理性能的影响.结果表明:苯丙乳液的掺入虽然在一定程度上降低了砂浆的抗压强度,但显著改善了水泥砂浆的和易性和需水量.通过掺加偏高岭土或煅烧膨润土等火山灰活性掺合料可弥补砂浆力学性能的不足.     

高活性偏高岭土制备最佳工艺参数的研究

偏高岭土（MK）是高岭土经过适当的温度煅烧后得到的一种高活性的矿物。它用作混凝土的掺合料对新拌混凝土和易性无不利影响,能够有效增加混凝土的强度,是优质的矿物掺合料。 1 煅烧温度对偏高岭土性能影响 1。1 样品的制备 分别取高岭土料5009试样置于快升温电炉中,经30min从室温分别升至600℃、700℃、800℃、900℃、1 000℃,保温2h后出炉,置于空气中自然冷却。1。2煅烧温度对偏高岭土活性的影响 所得偏高岭土经实验小球磨磨细,按10％的掺量配入水泥中检验强度,实验结果见表1和图1、图2。     

偏高岭土基地质聚合物的制备和力学性能研究

以高岭土为原料,煅烧为具有火山灰活性的偏高岭土,以NaOH,水玻璃为碱激发剂,标准养护条件下制备偏高岭土基地质聚合物。测试样品的力学性能,并利用XRD、SEM、DSC和TG、FT-IR等测试手段来研究矿物组成、反应机理、微观形貌;结果显示:高岭土的煅烧温度为800℃,煅烧时间2h,水玻璃模数为1.3,碱含量15%条件下,抗压强度最高可达72.10MPa。矿物聚合物的28d抗压强度相比于3d,7d有较大幅度提高。     

偏高岭土-水泥基材料力学性能研究进展

在配制水泥基材料过程中,利用活性材料替代部分水泥,可提高基体的力学和耐久性能,同时还可减少水泥用量,对节能减排有重大帮助.近年来偏高岭土(MK)活性材料开始受到广泛关注和研究,其对水泥基材料性能的影响研究也有重大进展.主要综述了MK对水泥基材料力学性能的影响研究进展,主要包括含杂质煅烧高龄粘土以及纯MK对砂浆和混凝土的早期和后期力学性能影响,MK与石灰石粉(LF)复掺对水泥基材料力学性能以及MK对超高性能混凝土(UHPC)的力学性能影响,最后对MK-水泥基材料的未来研究方向进行了展望.     

碱激发偏高岭土基地质聚合物的制备及抗压强度研究

为了响应“双碳”政策节能减排的号召,本文采用偏高岭土和高炉矿渣为原材料制备地质聚合物。以抗压强度为指标优化制备条件,探讨确定影响地质聚合物强度的因素。通过正交试验确定偏高岭土基地质聚合物的最佳配比,通过热重和XRD分析不同温度煅烧的偏高岭土组分。研究结果表明,在高岭土煅烧温度为800 ℃时,偏高岭土基地质聚合物的最佳配合比为氢氧化钠与硅酸钠的质量比为6.5∶1,激发剂的质量掺量为14.2%,其28 d抗压强度能达到46.6 MPa。偏高岭土基地质聚合物抗压强度随激发剂的掺量增加而增大,随氢氧化钠与硅酸钠的质量比的增大先增大后减小,随高岭土煅烧温度的升高先增大后减小。     

The effect of dehydroxylation/amorphization degree on pozzolanic activity of kaolinite

The effect of heat treatment parameters on the dehydroxylation/amorphization process of the kaolinite-based materials such as natural and artificial kaolin clays with different amounts of amorphous phase (metakaolin) was investigated. The procedure for quantitative estimation of amorphous phase in the heat-treated kaolinite materials was developed. The process of dehydroxylation/amorphization of kaolinite was characterized by DTA/TGA with mass-spectrometry and X-ray powder diffraction. The influence of the heat treatment temperature and content of the amorphous phase on pozzolanic activity was studied. Finally, the relationships between the chemical activity, activity strength index and the amorphous phase content were found and discussed. The results obtained are important for an optimization of the process of the metakaolin large scale production and it's use as an active pozzolanic admixture.     

煤系高岭岩制备偏高岭土实验研究

目前煤矸石已经成为中国乃至世界性的环保问题。通过对内蒙古包头市石拐矿区煤矸石进行调研、取样和试验研究,证明该煤矸石属于煤系高岭岩。利用石拐矿区煤矸石（煤系高岭岩）,经过磨细和800 ℃煅烧2 h,可以制备高活性的偏高岭土;将偏高岭土掺加到水泥胶砂中,可以提高胶砂的强度。煤矸石制备偏高岭土机理：石拐矿区煤矸石高硅富铝,而煅烧产生的游离二氧化硅和三氧化二铝成为其活性所在,采用先磨细后煅烧再粉磨的机械与热处理复合活化工艺,可以充分激发煤矸石煅烧制备偏高岭土的活性。     

Exploitation of poor Greek kaolins: strength development of metakaolin concrete and evaluation by means of k-value

In this paper, the effect of metakaolin on concrete properties is investigated. A poor Greek kaolin was thermally treated at defined conditions, and the produced metakaolin was superfine ground. In addition, a commercial metakaolin of high purity was used. Eight mixture proportions were used to produce high-performance concrete, where metakaolin replaced either cement or sand in percentages of 10% or 20% by weight of the control cement content. The strength development of metakaolin concrete was evaluated using the efficiency factor (k-value). The produced metakaolin as well as the commercial one imparts a similar behavior with respect to the concrete strength. Both metakaolins exhibit very high k-values (close to 3.0 at 28 days) and are characterised as highly reactive pozzolanic materials that can lead to concrete production with an excellent performance.     

高火山灰活性煅烧煤矸石添加量对水泥抗压强度的影响

为研究高火山灰活性下煤矸石添加量对水泥抗压强度影响,以龙岩翠屏山煤矿煤矸石为研究对象,分析了温度对煤矸石活性的影响以及煤矸石添加量对水泥强度的影响。结果表明:随着煅烧温度的增大,煤矸石烧失量在逐渐增大,烧失量与煅烧温度呈幂函数关系;随着煅烧温度的增大,煤矸石活性呈现先增大后减小的规律,煅烧煤矸石吸钙量与温度成二次多项式关系,推断实验煤矸石的煅烧最佳温度为750 ℃;随着煤矸石添加量的增加,水泥单轴抗压强度呈下降趋势,试件的抗压强度与煤矸石添加量成指数关系;随着龄期的增大,添加煤矸石的试件强度具有增长的趋势。研究结果对确定煤矸石添加量提供了理论依据,对指导煤矸石在凝胶材料中应用具有重要意义。     

Pozzolanic activity of mechanochemically and thermally activated kaolins in cement

This paper reports on the mechanochemical activation by intensive grinding as an alternative way to produce pozzolanically reactive metakaolin. The physicochemical properties, pozzolanic reactivity and impact on cement hydration of mechanochemically and thermally activated kaolinitic clays were compared. Mechanochemical activation of kaolin led to an amorphous hydrous material with increased specific surface area and high water content. Unlike in thermally activated kaolins, the Al coordination environment was partially retained during mechanochemical treatment. At low clinker replacement levels of 10%, the use of mechanochemically activated kaolins accelerated the hydration of the blended cement. The pozzolanic reaction reduced portlandite contents strongly and from early on. The combined effect of enhanced cement hydration and pozzolanic reaction at early ages was reflected in a higher early age strength development (up to 7 days). The differences between mechanochemically and thermally activated kaolins largely disappeared at later ages.     

Viability of using calcined clays, from industrial by-products, as pozzolans of high reactivity

The present work studies the use of clays like high reactivity metakaolin, as pozzolans for concrete. This study adopted two clay types: kaolinite and kaolin by-products from the paper industry. In this second clay, besides the possible technical advantages, the ecological benefit of the use of a by-product must be considered. Initially, the chemical and mineralogical characteristics of the clays were determined. After this, calcination and milling was carried out aiming at obtaining materials with pozzolanic activity. After milling took place in the clays kaolinite and in the by-products, with the best physical characteristics, lab tests were carried out to verify the pozzolanic activity of these materials with Portland cement and with lime. The results show a low performance of the kaolinite and a high performance of the by-products industrial. The low performance of the kaolinite was credited to the lack of homogeneity of the calcination, as the material was obtained after the calcination, and the low efficiency of its milling process.     

Evaluation of the pozzolanic activity of fluid catalytic cracking catalyst residue (FC3R). Thermogravimetric analysis studies on FC3R-Portland cement pastes

Spent fluid catalytic cracking catalyst (FC3R) from a petrol refinery has shown a great pozzolanic activity in lime pastes as have been demonstrated in previous studies. Based on these results, the pozzolanic activity of the FC3R in Portland cement pastes has been investigated. This evaluation has been carried out by means of thermogravimetry (TG) of cured FC3R-Portland cement pastes. The influence of water/binder ratio and the replacement percentage of FC3R on the pozzolanic reaction were investigated. Due to the chemical composition of FC3R that is similar to metakaolin (MK), and knowing that MK has a high pozzolanic activity, the latter was used as a material of comparison in the study of the water/binder ratio influence. The scope of this study is the determination of pozzolanic activity of FC3R when incorporated to Portland cement, and the evaluation on amount and nature of pozzolanic products. FC3R has shown a similar reactivity to MK, yielding similar pozzolanic products: CSH, CAH and CASH. The optimum replacing percentage in Portland cement pastes was in the 15-20% range.