石膏对阿利特─硫铝酸盐水泥性能的影响

研究了石膏对阿利特─硫铝酸盐水泥强度、凝结时间、干缩性等性能的影响。结果表明，掺加５％左右的石膏，可显著提高水泥强度，当掺量达约８％时，水泥的早期强度降低，更多的石膏则造成水泥安定性不良；石膏可延长水泥的凝结时间；存在适量石膏，水泥的干缩值减小。     

阿利特-硫铝酸盐水泥的试生产

阿利特－硫铝酸盐水泥是近年来出现的新品种水泥，该水泥熟料的主要矿物组成有C３S、C２S、C４A３S、C４AF和CS，所制成的水泥具有水化快、早期强度高、水化时体积收缩小或不收缩、耐腐蚀等优点。生产该水泥的主要矛盾是阿利特相和硫铝酸钙相在熟料中的共存问题。因为C４A３S主要是在１２００～１３００℃形成，１３５０℃以上开始分解，大于１４００℃时加速分解，而C３S则是在１４００℃左右才大量形成，所以降低熟料的煅烧温度是成功的关键。为此我们利用一些原材料的特性，降低熟料烧成时液相出现的温度以及液相粘度，从而使阿利…     

Fe2O3对阿利特-硫铝酸盐水泥熟料矿物形成影响的研究

以纯化学试剂配料,研究了Fe2O3对阿利特－硫铝酸盐水泥熟料矿物形成的影响。结果表明,低温下煅烧,Fe2O3不利于系统中fCaO的吸收;高温下煅烧,一定量的Fe2O3可促进C3S及C4A3S^-矿物的形成,有利于其在熟料中的共存;而当Fe2O3含量较高时,将会阻碍C3S的形成及降低C4A3S^-的含量。     

利用工业废渣烧制高贝利特硫铝酸盐水泥的探索性研究

以石灰石，工业废渣磷石膏，煤矸石为原料，根据设计的熟料矿物组成，设计4个废渣掺量－－12个不同的生料配比，研究不同配料的适宜煅烧温度和烧制出的高贝处特硫铝酸盐水泥熟料的矿物组成和水泥的物理性能，并寻找出废渣的适宜掺量范围。     

阿利特-硫铝酸盐水泥熟料的率值公式

根据阿利特-硫铝酸盐水泥熟料的矿物组成及生产控制要求,从理论上推导出其率值计算公式。并通过实例计算,验证了该公式的可行性。     

磷石膏作原料试生产硫铝酸盐水泥熟料

介绍了用磷石膏配料在回转窑上进行硫铝酸盐水泥试生产的情况。结果表明，用磷石膏配料，能改善生料的易磨性和易烧性，提高生、熟料的产量，并能改善熟料的凝结特性。根据磷石膏特点，在生产中需采取一些工艺措施，以使磷石膏得以充分利用。     

阿利特—硫铝酸盐水泥与硅酸盐水泥复合性能的研究

研究了阿利特－硫铝酸盐水泥与硅酸盐水泥复合所制备的水泥的性能。结果表明,复合后水泥的强度性能优于单一品种水泥的性能;凝结时间则由复合体中占比例较多的一种水泥所控制。     

利用煤矸石、工业石膏煅烧阿利特-硫铝酸盐水泥熟料

为获得向青海铝电公司提供高细石灰石粉（CaO含量≥52.0%,比表面积≥800m^2/kg）的供应权,我公司承诺全部处理脱硫渣（即工业石膏）.在成功运用工业石膏作水泥缓凝剂的基础上,我公司于2005年10月20日～11月20日进行了为期30d的利用煤矸石、工业石膏作原料配料,煅烧阿利特-硫铝酸盐水泥熟料的试生产.现就相关情况及操作经验作一介绍.     

Mechanically activated alite: New insights into alite hydration

For superior understanding of alite hydration an investigation of mechanically activated alite (M3 modification) was performed by XRD and heat flow calorimetry. Activation resulted in reduced particle size, a decreased mean crystallite size and partial amorphization. For the samples of activated alite a significantly accelerated and intensified hydration was observed and complete conversion of alite was found after 24 h. The enthalpy of reaction for crystalline alite was determined to be − 548 J/g from measured heat of hydration after 24 h. The enthalpy of reaction of amorphous “alite” was found to be less exothermic (− 386 J/g). The main hydration period is controlled by nucleation of C–S–H, while the transition from acceleration to deceleration period takes place after consumption of the small alite particles. XRD amorphous C–S–H phase is indicated to precipitate in considerable amount even in the highest activated alite before “long-range ordered”, XRD detectable C–S–H was observed.     

碱对阿利持—硫铝酸盐水泥熟料矿物形成及水泥性能的影响

以石灰石、粉煤灰、粘土、石膏等为原料,研究了K2O、Na2O对阿利特-硫铝酸盐水泥熟料矿物形成及性能的影响,结果表明,少量碱能改善水泥生料的易烧性,促进fCaO的吸收,过多的碱使C4A3∧-S矿物难以形成;当碱掺加量约1.2%时,NaO有利于C3S矿物的形成,并提高水泥的早期强度,而K2O则使C3S的形成量减少,水泥的强度降低;掺加碱使水泥的凝结时间延长。     

Properties of alite cements

For carrying out a comprehensive investigation on physical and mechanical properties of alite mortars and concretes, large quantities of monoclinic alite were produced at the University of California at Berkeley. Laboratory-size specimens were employed to determine strength, drying shrinkage, and sulfate resisting characteristics of mortars and concretes made with alite cements. Small amounts of gypsum (3%) addition accelerated the setting and hardening of the alite cements, however, large amounts (6%) resulted in strength deterioration. Drying shrinkage of alite concretes was significantly lower than portland cement concretes of the same fineness. Long term sulfate immersion of concrete specimens made with an alite cement caused serious spalling and strength loss.     

Silicate polymerization during the hydration of alite

The influence of admixtures and curing temperature on silicate polymerization during the hydration of alite was studied. Trimethylsilyl derivatives were separated by gel permeation chromatography. The major species identified in the hydrated pastes were dimer, linear pantamer, and linear octamer; at later ages, particularly at higher temperature, higher polymers are formed. A polymerization scheme is proposed. The effect of admixtures on silicate polymerization exactly parallels their effects on hydration.     

冷却速度对熟料中阿利特晶型影响研究

在相同煅烧条件下,同一个样品分别经过室温冷却、冷风下快速冷却和在炉子中慢速冷却制得不同熟料。利用X射线衍射技术分析不同冷却速度对熟料中阿利特晶型的影响,实验结果表明：室温冷却和快速冷却制得的熟料中阿利特晶型为M3型,慢速冷却制得的熟料中阿利特晶型为M1型。     

The influence of the alite polymorphism on the strength of the Portland cement

The influence of the alite polymorphism on the strength of cement was monitored in a set of laboratory-prepared clinkers with equal quantitative phase composition and different ratio of modifications. The alite polymorphism in clinkers was influenced by the change of the MgO and SO₃ side oxides in clinker, raw meal reactivity change, raw meal preheating, burning temperature or by the adding of crystallisation nuclei. The differences in the hydraulic properties of the M₁ and M₃ modifications were determined. In the case of all the hydration periods monitored, the strength of cements with the M₁ modification was 10% higher than the strength of cements with the M₃ modification.     

Effect of recrystallization on the characters of alite in Portland cement clinker

Alite, as well as belite, undergoes recrystallization during clinkering and grows large at the expense of small crystals. The growth is more noticeable in the direction perpendicular to (0001) than in the direction parallel to it. The crystals that are initially basal tablets become massive granules with the pyramidal faces well-developed. The recrystallization causes a considerable decrease in the concentration of the foreign ions in solid solution and thus occasionally lowers the crystal symmetry of elite to triclinic. These observations give evidence that the chemical composition of alite depends on its kinetics of crystallization from the interstitial melt.     

Effect of mixing on the early hydration of alite and OPC systems

The kinetics of hydration of cementitious materials is sensitive to the mixing procedure. High shear mixing conditions lead to an increase in the kinetics of hydration at early age compared to low shearing conditions such as hand mixing. In this study the effect of mixing speed and procedure was studied on alite and Portland cement in the presence or not of aggregates. The kinetics of hydration was monitored using isothermal calorimetry at 20 °C. The early reactivity was enhanced both with an increase in the speed of mixing and the shearing conditions. The principal features are a shortening of the induction period; a higher rate of hydrate precipitation during the acceleration period as well as an increase in the height of the main heat evolution peak. Analysis of the results in terms of dissolution theory, coupled with quantitative simulation with the μic modelling platform indicate different effects of mixing prior to and after the end of the induction period. Before the end of the induction period mixing has an impact on the rate of dissolution in the fast dissolution regime and high undersaturation, which appears to be (at least partially) controlled by the rate of transport of ions away from the alite surface. After the end of the induction period the main effect of mixing appears to be the production of more C-S-H nuclei, due to the possible detachment of the primary C-S-H (metastable) by mechanical action. This higher nucleation density leads to a denser microstructure for systems mixed at high intensities.     

The hydraulic behaviour of rhombohedral alite

A number of rhombohedral alites have been prepared using impurities of the type likely to be found in the alites of commercial cements. These alites when ground to 330 m²/kg developed between 25 and 90% more compressive strength at 28 days than monoclinic or triclinic alites. X-ray diffraction of alite pastes, in which hydration was arrested, indicates that rhombohedral alites yield higher strengths not only because they react more vigorously with water but, for the same degree of hydration the hydrates from rhombohedral alites contribute significantly more to strength. A mixture of rhombohedral alite with C₃A and $\text{CaSO}{}_4\text{.}\text{1}\text{2}\text{H}{}_2\text{O}$. developed much higher strengths at a given age than a similar mixture with triclinic alite.