大理石粉对水泥水化性能的影响研究

为研究大理石粉对水泥浆体水化性能的影响，采用X射线衍射仪、热重分析仪和核磁共振分析仪分析不同大理石粉掺量下水泥浆体的水化产物以及早期水化程度。结果表明：大理石粉的掺入会降低水泥浆体的抗压强度，并且下降幅度随掺量的增加而增大；掺入大理石粉的X射线衍射图没有新的物质生成，大理石粉掺量越高，水化产物Ca(OH)₂的衍射峰强度越小；大理石粉作为矿物掺合料可以提高水泥浆体中CaCO₃的含量；随着大理石粉掺量的增加，水泥浆体中胶空比逐渐增大，抗压强度也随之增大。     

水玻璃掺量对油基钻屑灰渣活性的影响与机理研究

为激发出油基钻屑灰渣的火山灰活性和阐明水玻璃掺量对其活性影响的作用机理,研究了灰渣在1.4模数水玻璃下根据不同碱掺比所制备的胶砂试件强度性能,并通过XRD、SEM和FTIR等测试技术分析试件的微观结构特征。结果表明：1.4模数水玻璃碱掺比在2%左右时,试件的3 d抗压强度和抗折强度较基准组分别提高了7.1%和16.7%,28 d龄期时的抗压强度提高了2.3%,碱掺比超过2%后,胶砂体系抗压与抗折强度均快速降低;微观测试结果表明2%的碱掺比能有效促进灰渣中的高聚态硅氧四面体解聚成低聚态,使得更多活性SiO₂、Al₂O₃参与二次水化反应,从而增加水化产物数量,提高整体结构密实性;过大碱掺比直接阻碍了水泥水化进程,体系内的Ca(OH)₂、AFt晶体和C-S-H凝胶数量大大减少,结构疏松多孔。     

大掺量粉煤灰早期活性激发及其作用机理

针对水泥基材料中大掺量粉煤灰早期激发效率低的问题,本文选取不同品种化学试剂以单掺、双掺的形式获得6种不同类型的激发剂,通过宏微观系列试验相结合的方法,确定激发剂的种类、掺量、复掺的最佳比例和粉煤灰激发要求的最低pH;并通过X-射线衍射法(XRD)、电子扫描显微镜(SEM)、微区能谱分析(EDS)、热重分析(TG)和氮气吸附测试(BET)探明激发剂的激发时效和激发机理。结果表明:Ca(OH)_2是粉煤灰水化的前提条件,双掺激发优于单掺,其最佳组合为Ca(OH)_2+Na_2SiO_3,比例为3∶1,最佳掺量为3%;粉煤灰掺量为50%时,单掺Ca(OH)_2和复掺激发剂的作用时效分别为7 d和3 d,维持粉煤灰-水泥体系能够反应的最低pH值是13.11; Ca(OH)_2+Na_2SiO_3激发剂既促进了水泥的水化又激发了粉煤灰早期活化,使粉煤灰结构在钠-钙-硫共同作用下快速裂解、水化,提高了粉煤灰-水泥的早期强度。     

炉底灰-粉煤灰胶凝体系的力学性能及微观分析

为实现炉底灰的大规模资源化利用,研究了原料掺量对炉底灰-粉煤灰胶凝体系力学性能的影响,采用X射线衍射、红外光谱、扫描电镜和能谱分析对胶凝体系水化产物的矿物组成、化学结构和微观形貌进行分析,结果表明:水泥掺量一定时,随着炉底灰掺量的提高,试样28 d抗压强度不断增大,而各龄期抗折强度及3,7 d抗压强度呈先增大后减小的趋势,粉煤灰对于提高胶凝体系早期强度具有不可或缺的作用,但掺量不宜过多;炉底灰可促进水泥中硅酸钙早期水化,生成更多氢氧化钙和钙矾石;水化后期,随着炉底灰掺量增大,C—S—H凝胶生成量增多并连接成密实的整体,针状文石晶体及纺锤形碳酸钙晶体桥接于水化试样微观裂隙两侧,阻碍裂隙的扩展,进一步提高胶凝试样的力学强度。     

活化粉煤灰水泥的微观结构研究

研究了不同种类活化剂对粉煤灰水泥的强度激发作用,通过改变活化剂及混合材掺量,对活化粉煤灰水泥进行了研制.使用X射线分析、红外光谱分析和扫描电镜分析等,从微观结构进行了研究.结果表明,活化后的32.5级粉煤灰水泥混合材掺量可高达35%.早强有明显提高.3 d抗折强度提高12.8%,抗压强度提高12.5%;微观结构主要表现为钙钒石,Ca(OH)2等水化产物大量出现和提前进行水化反应,3 d SEM显示结构紧密,为絮状形貌,3 d红外图谱显示波数发生位移.说明水化产物晶体结构发生了改变.     

粉煤灰增强碱渣填垫性能的试验研究

目前碱渣与粉煤灰拌合制成工程土大量用于填垫工程,更好地了解粉煤灰增强碱渣填垫性能强度机理有利于碱渣土在工程填垫方面的应用.以不同粉煤灰掺量的碱渣土界限含水率试验、击实试验、三轴试验和无侧限抗压强度试验为基础,结合微观电镜扫描试验,研究了拌合物碱渣土的强度特性,并且分析了粉煤灰增强碱渣强度的机理.结果表明:碱渣土的强度随着粉煤灰掺量、龄期和干密度增长而提高.当粉煤灰掺量较少时,前期主要作用是填充碱渣团聚体空隙,增加碱渣土密实度,随着龄期的增长,在碱渣的激发作用下会全部发生水化反应生成胶凝性物质提高碱渣土体系强度.当粉煤灰掺量较大时,由于碱渣的激发能力有限,粉煤灰一部分发生水化反应,一部分填充在碱渣空隙中提高碱渣土体系强度,且当粉煤灰掺量50%时水化反应与填充效果相对较为理想.     

硅灰-粉煤灰-废石粉对透水混凝土性能的影响

采用硅灰、粉煤灰、废石粉单掺及三元复合等质量代替部分水泥, 研究其对透水混凝土力学性能、透水系数及砂浆流动性的影响。结果表明: 随着硅灰掺量增加, 砂浆流动度先增加后减小, 透水混凝土强度逐渐增大, 透水系数先减小后增大, 当硅灰掺量超过6%时, 强度不再增加, 透水系数增大, 砂浆流动度 下降; 随着粉煤灰掺量的增加, 砂浆流动度不断增加, 透水混凝土强度与透水系数不断降低, 单掺粉煤灰时, 掺量不宜超过10%; 随着废石粉掺量的增加, 透水混凝土的抗压强度先增加后减少, 透水系数一直减小, 在掺量为 15%时强度最高。硅灰-粉煤灰-废石粉三元复合体系中, 掺6%硅灰、10%粉煤灰、10%废石粉的透水混凝土, 砂浆流动度为162mm, 28d 强度达到38. 4 MPa, 透水系数达到 4. 4 mm/ s。SEM 分析发现, 三元复合体系主要水化产物有水化硅酸钙凝胶和板状氢氧化钙, 还有少量针状钙矾石, 各水化产物之间连接较好, 浆体密实,水化产物发育较好, 浆体水化较完全。     

Ca(OH)_2和CaSO_4·2H_2O对粉煤灰水泥强度的影响

研究了外掺 Ca(OH)_2和 CaSO_4·2H_2O 对粉煤灰水泥强度的影响,并根据 X-射线定量、热分析和扫描电镜观察以及三甲基硅烷化试验结果进行解释。外掺 Ca(OH)_2降低粉煤灰水泥早期强度。虽然它可稍提高粉煤灰的反应率,但其反应率很低,除掺入量为5%者外,90天龄期的强度均稍低于未掺者。掺 CaSO_4·2H_2O 也使粉煤灰水泥早期强度降低,但掺量为2和4%者赶上不掺CaSO_4·2H_2O 的 4-28天强度所有掺 CaSO_4·2H_2O 的强度都超过90天龄期的未掺者。外掺的 CaSO_4·2H_2O 在28天内耗尽,由于生成钙矾石填充毛细孔空间而使结构致密后期强度提高。在采用相同体积水固比的情况下,无论掺还是不掺 Ca(OH)_2和 CaSO_4·2H_2O的粉煤灰水泥,其90天强度均低于纯波特兰水泥。在采用相同重量水固比时,后期强度赶上和超过波特兰水泥,不完全是粉煤灰的火山灰反应和形成钙矾石的结果,另一重要原因是粉煤灰和 Ca(OH)_2以及 CaSO_4·2H_2O 的比重小而使浆体初始总孔隙率低。三甲基硅烷化试验结果表明,粉煤灰中的 SiO_2主要以多聚物形式存在,单聚物只占8%左右,这可能是粉煤灰活性低的原因之一。外掺 Ca(OH)_2和 CaSO_4·2H_2O 的粉煤灰水泥浆体,60天龄期的单聚物减少而三聚以上的多聚物增多。     

超细粉煤灰与原灰在水泥砂浆中的水化特征对比研究

主要对比研究了粉煤灰原灰颗粒和超细粉磨后的粉煤灰颗粒在水泥砂浆中的水化过程,利用SEM对水化行为进行了微观观察,并结合砂浆试块3 d7、d、28d抗折、抗压强度.结果表明:粉煤灰的细度对试块的强度影响最大,尤其是后期对抗压强度,在相同掺量下,强度相差达2倍左右;粒径在5μm左右的粉煤灰颗粒在养护初期就已经开始水化,且水化速率较快,在28 d时水化程度已经很充分,粉煤灰原灰颗粒即使养护到28 d龄期时,水化程度仍然很低;掺入细灰的试体各个龄期的结构均比原灰的要致密,且钙矾石的生长更快.     

高钙粉煤灰作为添加剂制备赤泥偏高岭土胶凝材料

采用XRD、IR、SEM、和EDS等分析手段,研究了高钙粉煤灰作为添加剂制备的赤泥偏高岭土胶凝材料的力学性能和水化产物.结果表明:合适掺量的高钙粉煤灰(<14%)有助于试样力学性能的提高;高钙粉煤灰作为添加剂所制备的赤泥偏高岭土胶凝材料,其水化产物主要有水化硅酸铝钙、沸石相、羟基硅酸铝、钙长石、蓝晶石、水化硅酸钙和叙永石. 随着试样养护龄期的增长胶凝材料结构更密实,形成PSS型结构.     

Preparation of new cementitious system using fly ash and dehydrated autoclaved aerated concrete

We experimentally studied the interaction between pozzolanic material(fly ash) and dehydrated autoclaved aerated concrete(DAAC). The DAAC powder was obtained by grinding aerated concrete waste to particles fi ner than 75μm and was then heated to temperatures up to 900 ℃. New cementitious material was prepared by proportioning fly ash and DAAC, named as AF. X-ray diffraction(XRD) was employed to identify the crystalline phases of DAAC before and after rehydration. The hydration process of AF was analyzed by the heat of hydration and non-evaporable water content(Wn). The experimental results show that the highest reactivity of DAAC can be obtained by calcining the powder at 700 ℃ and the dehydrated products are mainly β-C2 S and CaO. The cumulative heat of hydration and Wn was found to be strongly dependent on the replacement level of fl y ash, increasing the replacement level of fl y ash lowered them in AF. The strength contribution rates on pozzolanic effect of fl y ash in AF are always negative, showing a contrary tendency of that of cement-fl y ash system.     

复合浆体中粉煤灰和水泥水化反应程度的测定

采用盐酸选择溶解法测定粉煤灰的水化程度,再结合水化热法计算复合浆体中水泥的水化程度。试样结果表明,在水化早期粉煤灰仅作为惰性材料填充于复合浆体的孔隙中。随着粉煤灰掺量的增大,水泥的水化程度越高,单位体积中水化产物的总体数量仍为减少。     

化学激发剂对废弃粗粉煤灰火山灰活性的影响

通过研究不同化学激发剂对废弃粗粉煤灰-水泥系统的强度发展、水化程度、水化产物等的影响，发现掺入Na2SO4和K2SO4可以大幅提高废弃粗粉煤灰-水泥系统在早期和晚期的抗压强度，而掺入CaCl2和Ca(OH)2的效果则不明显，X射线衍射的测试结果也证明了这一点。由此说明化学激发废弃粗粉煤灰的火山灰活性重点在于提高系统的pH值。另外，水化程度测试的结果显示，化学激发剂对粗粉煤灰的促进作用主要集中在28d以前。     

Hydration Kinetics of Municipal Solid Wastes Incineration(MSWI) Fly Ash-Cement

Hydration heat behavior and kinetics of blended cement containing up to 20% MSWI fly ash were investigated based on its hydration heat evolution rate measured by isothermal calorimeter. Kinetics parameters, N and K, and hydration degree, Ca(OH)_2 content, were also calculated and analyzed. According to the experimental results, the induction period was elongated, the second heat evolution peak was in advance, and the third hydration heat peak could be detected due to MSWI fly ash pozzolanic reaction. The hydration reaction rate was controlled by nucleation kinetics in the acceleration period and then by diffusion in the decay period, but in the deceleration period, the hydration experienced a dual controlling reaction of autocatalytic chemical reaction and diffusion. The hydration rate of blended cement was faster. Ca(OH)_2 content increased before 14 days.     

蒸养超细粉煤灰高性能混凝土性能试验研究

研究蒸养条件下超细粉煤灰高性能混凝土的强度、弹性模量和应力-应变行为以及体积稳定性和耐久性能,结合微观测试手段,探讨超细粉煤灰在蒸养条件下的作用效应及其机制.试验结果表明,超细粉煤灰能显著提高混凝土的蒸养适应性,蒸养超细粉煤灰高性能混凝土的后期强度、弹性模量具有较好的增长率.与普通蒸养混凝土相比,蒸养超细粉煤灰高性能混凝土的脆性降低,塑性变形能力明显增强,干燥收缩明显降低,且抗氯离子渗透性能显著提高.超细粉煤灰可改善蒸养条件下混凝土的内部水化产物组成及其孔结构,降低混凝土的孔隙率,提高混凝土耐久性.     

Deterioration Characteristics of Cement-Fly Ash Paste under Strong Ultraviolet Radiation and Low Temperature Conditions

The pastes containing different dosages of fly ash were taken into ultraviolet radiation and low temperature freeze condition simultaneously(URL) for 30 days and only ultraviolet radiation condition(UR) for 30 days after standard curing, so as to investigate the influences of the conditions on the deterioration characteristics of the pastes. Microscopic test methods, such as XRD, TG-DTA and SEM, were used to study the UR effect on the deterioration process of hardened paste. The results show that the deterioration tests, such as URL and UR, inhibit the common development of paste strength, especially after the standard curing age of 360 days. With the increase of fly ash dosage, from 0 to 50%, the reference value decreases, especially at early age. While at the later age, i e, 180 and 360 days, the paste strength cured for 30 days under URL and UR conditions all increase to different extent and the strength is slightly affected very low, especially for the paste containing 25% fly ash. From XRD results, URL and UR dispositions do not influence the hydration product kinds but the amount, especially Ca(OH)₂ and CaCO₃. Deterioration experiments can decrease the diffraction peak of Ca(OH)₂ sharply, and increase that of CaCO₃ rapidly, especially under only ultraviolet radiation. From TG-DTA and SEM results, with the increase of curing age, the content of Ca(OH)₂ decreases and that of CaCO₃ increases. The Ca(OH)₂ content of paste under continuous UR curing for 30 days is less than that under URL curing for 30 days, which indicates that UR has more negative effects on the pastes than URL.     

THE INFLUENCE OF TEMPERATURE AND ADMIX- TURES ON ACTIVATION OF LOW CALCIUM FLY ASH

According to composition and structure properties of low calcium fly ash, the activation and reaction degree of fly ash—lime and fly ash—lime—gypsum system were studied in different alkali surroundings and temperatures by thermal-gravity analysis. The degree of reaction and pore structure analysis test results show that composite alkali play an important role in the activation and degree of reaction of fly ash at room temperature. But when increasing curing temperature, gypsum would play an important role in activation and hydration of fly ash.     

Microstructure and Composition of Hydration Products of Ordinary Portland Cement with Ground Steel-making Slag

1　IntroductionSteel makingslagisthewasteofsteel makingindus tryandnearlysixteenmilliontonssteel makingslagisproducedinChinaperyear[1] .Justasflyashandblastfurnaceslag ,itisoneofthreekindsofdominantindustrywastesinourcountry .Eventhoughsteel makingslagce menthasdevelopedformorethantwentyyearsinCh ina[2 ,3 ] ,comparedwithothertwowastes ,thestudyandap plicationonsteel makingslagincementandconcreteareinsufficientyet.Moststeel makingslagcementsarepre paredbyinter grindingprocess ,sotheparticlesiz…     

废弃粉煤灰火山灰活性的研究

通过对细粉煤灰与废弃粗粉煤灰在强度发展、水化程度、水化产物等方面的对比 ,发现粗粉煤灰在 90 d的强度发展和水化速度大于细粉煤灰。水灰比 ( W/ C)对粉煤灰尤其是粗粉煤灰的火山灰反应影响重大 ,随着水灰比的增加 ,掺粗粉煤灰样品的强度和水化程度都成倍增长。这主要是由于高水灰比有利于 Ca2 和粉煤灰中溶出的活性成分进入溶液参与反应。这可从扫描电镜 ( SEM)的测试结果得以证实     

活化复合水泥的研制与早期微观结构研究

通过对活化硅酸盐类水泥的研制，结果表明：活化后的32．5级复合硅酸盐水泥早强有显著提高，助磨效果明显，混合材最高掺量可达60％。其3d抗折强度增长215％，抗压强度增长39．4％；28d抗折强度增长27．8％，抗压强度增长6．4％，通过使用现代测试手段进行的分析，结果表明：主要表现为钙钒石、Ca（OH）2等水化产物大量出现和提前进行水化反应，3dSEM显示结构紧密，为絮状形貌，3d红外图谱显示波数发生位移，说明水化产物晶体结构发生了改变。3dX射线显示，Ca（OH）2水化产物相应发生变化，量热分析显示出反应热增加。