掺混合材和硫酸钠水泥石可溶出Na+的实验

目的 分析在掺加Na2SO4后,粉煤灰、矿粉、水泥以及不同粉煤灰、矿粉掺量的水泥石中不同水化龄期的可溶出Na+量,进而研究Na+对混凝土的潜在破坏性.方法 利用溶出法对不同水化龄期样品进行处理,再利用离子选择性电极法对样品中的可溶出Na+量进行化学分析,以此来研究对水泥石仍有影响的Na+量随水化龄期的变化.结果 Na2SO4掺量超过2%时,水化早期的可溶出Na+量有较大幅度的提高;在水泥、粉煤灰和矿粉中,固化Na+量最大的是粉煤灰;Na2SO4掺量2%时,胶凝材料中掺入粉煤灰可明显降低可溶出Na+量,胶凝材料中矿粉掺量越高可溶出Na+量越高.结论 使用Na2SO4时,应将用量控制在2%以下;水泥中复合粉煤灰可显著提高固化Na+的能力,粉煤灰的适宜掺量为30%;水泥中复合矿粉会降低固化Na+的能力.     

混合材对高C3S含量水泥水化性能的影响

通过测定不同龄期和掺量的煤矸石-水泥、超细粉煤灰-水泥复合体系力学性能、结合水量及混合材反应程度，并结合XRD研究了低水胶比下超细粉煤灰、活化煤矸石对高C3S含量水泥水化性能的影响。试验结果表明，粉煤灰的化学效应对高C3S含量水泥早期水化的影响与煤矸石相差不大，但是其物理特性对高C3S含量水泥早期强度的影响要高于煤矸石；而活化后的煤矸石对高C3S水泥后期水化的影响优于超细粉煤灰，其抗压强度、结合水量和混合材反应程度均高于粉煤灰-水泥复合体系；活化煤矸石单独与高C3S水泥复合使用时，其掺量可比Ⅱ级粉煤灰提高20％。     

粉煤灰硅酸盐水泥的研制

研究在不同掺量、不同水胶比、不同养护龄期下粉煤灰硅酸盐水泥的水化进度、各组分含量以及各项力学性能.明确粉煤灰在水泥基材料中所发挥的作用,了解粉煤灰在水化过程中对各组分产物形成某些特定的影响,作为粉煤灰在水泥基材料中的合理有效应用提供理论依据和实践指导.     

掺混合材和硫酸钠水泥石可溶出SO42-的实验

目的 分析在掺加Na2SO4后,粉煤灰、矿粉、水泥以及不同粉煤灰、矿粉掺量的水泥石中可溶出SO42-的量,进而研究SO42-对混凝土的潜在破坏性.方法 利用溶出法对不同水化龄期样品进行处理,再利用BaSO4重量法对样品中可溶出SO42-的量进行化学分析,以此来研究SO42-量随水化龄期的变化.结果 水化28 d时,Na2SO4掺量低于2%的水泥石中已测不出SO42-,而Na2SO4掺量高于2%的水泥石中仍有可溶出SO42-;在水泥、粉煤灰和矿粉中,固化SO42-速率最快的是矿粉,固化SO42-量最大的是水泥;Na2SO4掺量2%,水化7d之前,水泥中粉煤灰掺量越高可溶出SO42-量越大,矿粉掺量越高可溶出SO42-量越小.结论 普通水泥混凝土中Na2SO4掺量不应高于2%;固化SO42-的速率由快到慢为矿粉、水泥和粉煤灰;固化SO42-的量由高到低为水泥、矿粉和粉煤灰;水泥中复合粉煤灰后固化SO42-的速率变慢;水泥中复合矿粉后固化SO42-的速率变快.     

焦作地区工业废渣分析与应用研究

对焦作地区主要工业废渣进行了成分分析,并与硅酸盐水泥作了比较;同时,对工业废渣在水泥生产和混凝土工程中的应用作了研究,当使用激发剂时,水泥中的矿渣掺量可达70%;粉煤灰掺量为20%时,基本上不降低水泥的强度;粉煤灰代砂配制混凝土,当代砂量为30%时,90d强度可提高30%.     

中热水泥-粉煤灰体系的贫钙问题

为了提高水工大体积混凝土中的粉煤灰掺量,研究了中热水泥 粉煤灰体系的贫钙问题.通过抗折和抗压强度试验研究了粉煤灰掺量对中热水泥-粉煤灰体系的强度的影响，通过水化率测定和XRD分析研究了中热水泥-粉煤灰体系的水化特性.结果表明：在强度实验中，粉煤灰存在一个允许掺量，这个掺量随着养护龄期的增长而提高0.3 d和28 d时，允许掺量小于10%， 而在3.5a时，允许掺量高达65%以上；体系中粉煤灰的水化速率很慢，粉煤灰明显降低了体系中的Ca(OH)₂，随着粉煤灰掺量增加和龄期延长，Ca(OH)₂减少.在中热水泥-粉煤灰体系中并不存在贫钙问题.     

热-机械复合活化煤矸石掺量对普通硅酸盐水泥水化产物的影响

为了解决热-机械复合活化煤矸石掺量对普通硅酸盐水泥水化产物的影响问题,采用X射线衍射(XRD),扫描电子显微镜(SEM),能量色散谱(EDS)和微机控制抗压折一体机,对掺有热-机械复合活化煤矸石水泥的抗压强度、水化过程、水化产物的微观结构、化学组成、形貌特征和水化产物水化硅酸钙C—S—H凝胶的钙硅比进行了研究。结果表明：活化煤矸石的掺入不仅参与了水泥水化反应,水化生成更多低n(Ca)/n(Si)的C—S—H,而且活化煤矸石中的活性物质将高硫型水化硫铝酸钙AFt转化成单硫型水化硫铝酸钙AFm,使得孔结构得到了优化,但是活化煤矸石的掺量不宜大于30%,过多活化煤矸石的掺量使CH含量减少,导致水泥试块91 d龄期的抗压强度明显降低。     

低水胶比下粉煤灰对水泥早期水化的影响

提出可用等效结合水含量和水化影响因子来定性和定量分析粉煤灰对水泥早期水化作用的大小。若粉煤灰的水化影响因子 >1,则粉煤灰促进水泥水化 ,值越大 ,促进作用越显著 ;若粉煤灰的水化影响因子 <1,则粉煤灰延缓水泥水化 ,值越小 ,延缓作用越显著。同时研究和分析了低水胶比下粉煤灰不同品种和掺量对水泥早期水化的影响     

利用高钙粉煤灰生产粉煤灰水泥的试验研究

研究了高钙粉煤灰水泥的细度及活性激发剂对其物理性能的影响。研究结果表明,高钙粉煤灰水泥的安定性和各龄期的抗折、抗压强度均随着水泥的细度的提高和活性激发剂的掺入而提高,活性激发剂具有加速水泥矿物和ｆ Ｃａ Ｏ 水化的作用。采用５２５＃ 熟料,掺加３０％ 的高钙粉煤灰时,水泥的比表面积在３４０～４００ ｍ ２ ／ｋｇ 和掺入１％ 的活性激发剂,能够稳定生产４２５＃ 高钙粉煤灰水泥。     

氧化石墨烯改善高贝利特水泥性能的研究

试验研究了不同掺量的氧化石墨烯(GO)对高贝利特水泥(HBC)材料流动度、强度、水化热和微观结构的影响.结果表明:水泥胶砂流动度随着GO掺量的增加而降低;单掺GO对试件各龄期强度的增强效果不明显,而复掺PC/GO可明显提高试件各龄期的强度,且当GO掺量为0.05%时,试件各龄期的抗折强度和抗压强度均达到最佳,与基准试件相比,其强度得到明显提高;同时GO对水泥各龄期的水化热还有降低作用.由SEM、XRD分析表明,掺入GO可提高水泥材料的密实度,促进水化产物(C-S-H)和钙矾石AFt的形成,从而达到增强效果.     

煤矸石代替黏土生产水泥可行性分析

为了研究煤矸石代黏土生产水泥的可行性,对10个省份28个矿点进行取样,开展煤矸石特性分析.分析结果表明,煤矸石具有高灰分、高硫分和低热值等特点,化学成分与黏土相近,还含有较丰富的微量元素和矿物组成.对煤矸石、中钙石灰石和硫酸渣等配料进行煅烧试验,试验表明,煤矸石在煅烧时,微量元素和矿物释放其储存的地质能量,加速促进硅氧键的断裂,比黏土配料更早生成硅酸三钙、硅酸二钙和铝酸三钙等水泥熟料矿物.煅烧过程中放出的二氧化硫与钙铝氧化物反应形成早强硫铝酸盐水泥熟料矿物,从而减少硫化物对环境的污染.     

Early hydration of composite cement with thermal activated coal gangue

Composite cement samples were prepared by mixing clinker, gypsum with burnt coal gangues which was calcined at various temperatures. The mechanical strength and Ca(OH)₂ content in the cement paste were tested, and the paste composition and microstructure were analyzed by thermogravimetry-differential thermal analysis (TG-DSC), X-ray diffraction(XRD), scanning electronic microscopy (SEM) and pore structure analysis. Results demonstrate that the thermal activated coal gangue could accelerate the early hydration of cement clinker obviously, which promotes the gangue hydration itself. The early hydrated products of the cement are C-S-H gel, Ca(OH)₂ and AFt. The cement with 30% (in mass) the gangue exhibits higher mechanical strength, and among all the cement samples the one with the gangue burnt at 700 °C displays the highest hydration rate, mechanical strength, the most gel pores and the lowest total porosity.     

Performance of cemented coal gangue backfill

Possibility of cemented gangue backfill was studied with gangue of Suncun Coal Mine, Xinwen Coal Group, Shandong, and fly ash of nearby thermal power plant, in order to treat enormous coal gangue on a large scale and to recovery safety coal pillars. The results indicate that coal gangue is not an ideal aggregate for pipeline gravity flow backfill, but such disadvantages of gangue as bad fluidity and serious pipe wear can be overcome by addition of fly ash. It is approved that quality indexes such as strength and dewatering ratio and piping feature of slurry can satisfy requirement of cemented backfill if mass ratio of cement to fly ash to gangue is 1：4：15 and mass fraction of solid materials reaches 72%-75%. Harden mechanism suggests that the cemented gangue fill has a higher middle and long term comprehensive strength.     

Paste-like self-flowing transportation backfilling technology based on coal gangue

A paste-like self-flowing pipeline transportation backfilling technology with coal gangue as aggregate is proposed to remove the potential damage caused by coal gangue piles. As well, the difficult problems of recovering high quality safety coal pillars and deep mining of the Suncun Coal Mine (SCM), Xinwen Coal Group, Shandong are resolved. The physical-chemical properties of coal gangue, optimized proportion of materials, backfilling system and craft in the SCM were studied in the laboratory and then an industrial test was carried out on high quality coal pillars under a town. The results show that finely crushed kaolinized and fresh gangue with granularity less than 5 mm can be used as aggregate with fly ash to replace part of the cement and a compos-ite water reducer as an additive, accounting for 1.0%-1.5% of the total amount of cement and fly ash. The recommended proportion is I(cement):4(fly ash): 15(coal gangue), with a mass fraction of 72%-75%, theological paste-like properties and a strength of more than 0.7 MPa at 7 d. The sequence of adding cement, fly ash, water reducer and then coal gangue ensures that the suspended state of the slurry, reducing the wear and jam of pipelines. The working face is advancing continuously by the alternating craft of building block walls with coal gangue and backfilling mined-out gobs with paste-like slurry. The recovery rate is as high as 90% with a backfilling cost of 36.9 Yuan/t, good utilization of coal gangue and no subsidence on the surface. This technology provides a good theoretical basis and application experience for coal mines, cement backfilling with paste-like slurry.     

低碱低掺混凝土膨胀剂的试验研究

利用不同的原料配制了多组低碱低掺型混凝土膨胀剂．测定了各膨胀剂的膨胀性能及其对水泥物理力学性能的影响．利用SEM分析了掺膨胀剂水泥的水化产物、结构和形貌．研究结果表明,利用SA熟料、无水石膏、煤矸石和硅铝质矿物原料配制的膨胀剂具有良好的膨胀性能,并对水泥的物理力学性能无不良影响;掺膨胀剂水泥在一定时期内会持续形成大量的呈交又生长的针状钙矾石,它们填充在孔隙内,使水泥石结构致密．     

Influence of ultra-fine fly ash on hydration shrinkage of cement paste

1INTRODUCTION Hydrationshrinkageisalsoknownaschemicalshrinkage[1].Thesolidvolumeincreasesafterce menthydrating,buttheabsolutevolumeofcementwatersystemreduces.Usuallythetotalamountofvolumeshrinkageofcementwatersystemis7%9%[1,2].Withthedevelopmentofthetechno logyofcementandconcrete,concretewithhighstrengthandhighperformanceisthedevelopingtendencynow.However,nowadays,comparedwithordinaryconcrete,thehydrationshrinkageofhighperformancecementconcreteincreasesobvi ouslybecauseoftheaccelerationof…     

Physical Properties and Hydration of Cementitious Materials Prepared from Vanadium Slag and Phosphate Slag

The physical properties and hydration of a cementitious material, which prepared mainly from the vanadium slag and phosphate slag, were investigated. These slags were investigated can be reused as original resources to prepare cement clinker based on the fact that they mainly comprise silicon and calcium phases, respectively. In this research, a batch of cement having various grades was prepared by mixing the clinker with gypsum, tailings, and fly ash. X-ray diffraction(XRD), differential thermogravimetric(DTG) as well as scanning electron microscopy(SEM) were applied to test and analyze the physical properties and hydration of the prepared cement. Experimental results suggest that the performances of the cement meet the requirements of national standards in all aspects. Its hydration process is similar to that of common Portland cement, whose hydrates were mainly composed of C-S-H, ettringite and CH. Moreover, the addition of fine particles would accelerate cement hydration, as it provided additional surfaces to help the nucleating and growing of hydrates.     

Pozzolanic Activity of Burned Coal Gangue and Its Effects on Structure of Cement Mortar

The pozzolanic activity of coal gangue burned at different burning temperatures was investigated. The burned coal gangue was mixed with portland cement in different proportions （ 20% - 60% ）. The pozzolanic activity of coal gangue burned and the hydration products were examined, the compressive strengths of the pastes of the mixtures were tested, and the mechanism of the reaction was discussed. The experimental results slum, that the coal gangue burned at 750 ℃ has the optimum pozzolanic activity, and the burned coal ganguc with SiO2 and Al2 O3 is in an active form. When the coal gangue burned at 750℃ is mixed into portland cement, the content of calcium hydroxide in paste is significantly reduced, while the contents of hydrated calcium silk.ate and hydrated calcium aluminate are increased accordingly, hence resulting in the improvement of the microstructure of mortar. The compressive strength of cement paste decreases with increasing the content of burncd coal gangue. The decease in strength is small in the range of 20% - 30% coal gangue substitution and significant in 30%- 60% substitution.     

自燃煤矸石细粉、粉煤灰制备泡沫混凝土的试验研究

本研究利用硅酸盐水泥和自燃煤矸石细粉、粉煤灰等混合材料,采用预制气泡后混合的方法制备出高性能泡沫混凝土,并研究了自燃煤矸石细粉、粉煤灰泡沫混凝土的干表观密度对泡沫混凝土的抗压强度与导热系数的影响。研究结果表明,随自燃煤矸石细粉、粉煤灰泡沫混凝土干表观密度的增加,泡沫混凝土抗压强度和导热系数也增加。