改性增强天然硬石膏的应用研究

该文主要介绍了激发剂改性增强天然硬石膏的效果和变化趋势,探索不同含量激发剂对天然硬石膏的影响程度,对比分析复合激发剂不同配比和增加减水剂对天然硬石膏熟粉强度的影响,研究结果表明复合激发剂和减水剂组合配比对天然硬石膏熟粉的强度的影响最显著。     

天然硬石膏的活性激发与改性研究

本文研究了细度与激发剂对天然硬石膏的水化及其硬化体性能的影响。采用提高原料细度的物理方法和选用合适激发剂的化学方法，使天然硬石膏的活性得到有效激发，并使其水硬性有所增强。本中还对细度与激发剂对天然硬石膏的改性机理进行了探讨。     

激发剂对天然硬石膏的改性研究

通过测定凝结时间和不同龄期绝干抗折、抗压强度,分析研究盐类和碱性激发剂对天然硬石膏的改性效果,对比优选出硫酸钠作为合适单一激发剂.在自制激发剂基础上通过与硫酸钠复配,最终获得掺量小、效果好,对硬石膏制品副作用小的高效复合激发剂.研究结果表明,在合适激发剂的激活下能够获得凝结硬化快,7d抗折、抗压强度分别达9.00MPa、30.0MPa的天然硬石膏建筑胶凝材料.     

快硬早强高强天然硬石膏胶凝材料的试验研究

以无机盐和复合矿粉作为天然硬石膏的复合激发剂。在复合激发剂的作用下天然硬石膏能较快速地凝结硬化,具有快硬早强、高强的性能,1d抗压强度达到10～20MPa,28d抗压强度达到35～45MPa。     

天然硬石膏的水化研究

本文以天然硬石膏为原料,用硫酸钠、硫酸氢钠、碳酸钾、硫酸钾、氧化钙和复合激发剂FG为激发剂,分别测试硬石膏的3d水化率。结果表明：硫酸氢钠激发水化效果好于硫酸钠;硫酸钾的激发水化效果好于碳酸钾;在这几种激发剂中,复合激发剂FG的激发水化效果最好,FG加入3%时,3d水化率达到63.8%。     

天然硬石膏的活性激发及改性

选取硫酸钾作为激发剂对天然硬石膏进行活性激发,并分别掺入硅酸盐水泥与半水石膏进行改性。研究了这些组分对天然硬石膏力学性能及耐水性能的影响规律,实验结果表明,硫酸钾对强度提高显著,硅酸盐水泥对强度与软化系数均有很大的改善作用,而半水石膏对强度与软化系数也有一定程度的影响。     

硬石膏激发试验研究

硬石膏水化进程缓慢,98 d水化率才达到64.05％,掺入适量激发剂可以较大幅度提高硬石膏水化率,加快硬石膏水化进程:其中煅烧明矾的激发效果最好.SEM分析结果表明,激发剂可以改变硬石膏硬化体晶体形貌.     

硬石膏基地面自流平材料研究

利用天然硬石膏进行了地面自流平材料试验研究,研究表明,通过添加半水石膏、增强材料、细砂、粉煤灰以及激发剂、高效减水剂、消泡剂、保水剂复合掺用,配制的硬石膏基自流平材料扩展度达310 mm,砂浆抗压强度15M Pa,抗折强度2.25 M Pa,达到了日本与欧洲标准的要求,具有一定的市场前景。     

硬石膏复合改性研究

在硬石膏复合激发体系的基础上对硬石膏进行煅烧改性，并研究复合激发体系中外掺料、外加激发剂用量改变对硬石膏胶凝性能的影响，将多种改性因素结合，使硬石膏的改性研究取得了较好的结果。     

磷石膏生产硬石膏的研究

磷石膏生产硬石膏的研究董坚张化（山东建工学院）硬石膏是以天然或化学二水石膏经高温烧成的Ⅱ型无水石膏。经磨细加入适量激发剂即可水化。水化后的制品具有抗湿、抗裂强度高，不收缩等优良特性。即使在潮湿情况下仍能保持较高的致密性和强度。利用磷石膏可生产硬石膏，...     

天然硬石膏粉刷材料

简介了天然硬石膏粉刷材料的原料、生产工艺、产品性能及工程应用,根据工业性试生产结果,进行了初步经济分析。我国硬石膏资源丰富,对这种性能价格比好的粉刷石膏新品种应大力推广。     

钛酸酯偶联剂表面改性硬石膏粉的研究

作者研究了经钛酸酯偶联剂改性的硬石膏粉的表面性质、改性前后硬石膏粉对聚氯乙烯(PVC)复合材料的力学性能的影响以及改性前后硬石膏粉与PVC的结合情况.研究表明:改性后的硬石膏粉表面性质由亲水变成亲油;SEM照片显示改性后硬石膏粉与PVC相容性好;力学性能测试表明改性粉体明显改善了复合材料的力学性能,尤其是冲击强度提高了17%～31%;FT-IR分析表明,钛酸酯偶联剂与硬石膏粉的表面以化学健结合.文章还阐述了钛酸酯偶联剂改性硬石膏粉的机理.     

有效利用工业废渣制备混凝土高效膨胀剂的研究

介绍了利用工业生产过程中生成的含硫废渣,部分取代膨胀剂膨胀组分中的天然硬石膏,制备混凝土高效膨胀剂,从而研究工业废渣取代量和形态对其限制膨胀率、抗压强度、凝结时间等性能的影响.     

Effects of evaporite removal on the mass properties of limestone

A considerable thickness of anhydrite has been removed by solution from Magnesian Limestone of County Durham in North-east England. To the west the extent of the anhydrite was formerly limited by the front of the well known Permian reef complex. The anhydrite beds thickened to the east and have been proved in borings a few miles offshore. Solution of the anhydrite has been ascribed to circulating groundwaters. The general circulation, and hence solution of anhydrite, would have been limited to the east by the fresh to saltwater interface approximately coincident with the present coastline. By using the methods available for predicting ground strains and subsidence associated with the underground mining of coal seams, it is possible to predict:

1. the direction and position of maximum surface strain in the limestones above the anhydrite
2. the localiation of brecciation in the associated limestones as the anhydrite was removed.

The resultant changes in the mass properties of the formerly well-bedded limestones are described and discussed.     

Study on anhydrite plaster from waste phosphogypsum for use in polymerised flooring composition

The paper deals with an investigation about the production of high strength plaster from the waste phosphogypsum and its use in making flooring tiles. To achieve this objective, phosphogypsum was calcined at 900–1000 °C to anhydrite which was mixed with suitable chemical activators (alkali/alkaline earth hydroxides, sulphates, carbonates) and finely ground (>400 m²/kg Blaine's) to achieve high compressive strength (36–37 MPa). The anhydrite plaster was blended with 2–3% of predetermined quantity of a monomer methyl methacrylate (MMA) with a compatible catalyst, metalic oxide pigments, fly ash or red mud, chopped glass fibres (E-type, 12 mm long) and quartz sand to form flooring tiles by vibration moulding technique followed by high humidity curing, drying, grinding and polishing. The addition of chemical activators increase the rate of dissolution of anhydrite for rapid transformation into hard strong gypsum matrix while the MMA gets polymerised during hydration of anhydrite into polymethyl methacrylate which fills up voids and pores of hydrating anhydrite and thus improves density, strength and durability of the anhydrite plaster against water. The durability of anhydrite plaster by alternate wetting and drying and heating and cooling cycles is reported along with hydration mechanism. The use of phosphogypsum anhydrite for making high strength plaster and flooring tiles is recommended.     

利用磷石膏研制混凝土高效膨胀剂

本文介绍了利用工业废弃物磷石膏煅烧脱水制取硬石膏,再与特制高铝熟料配合研制混凝土高效膨胀剂.     

Study on the geological and engineering aspects of anhydrite/gypsum transition in the Arabian Gulf coastal deposits

Evaporitic geology, hot and arid climate, fluctuating relative humidity, and an alkaline environment governed the evolution of sedimentary deposits in the Arabian Gulf coast. Calcium sulphate generally occurs as anhydrite in the unsaturated surface layer of local soil formations. Anhydrite hydrates to gypsum with an associated volume increase of up to 63%, whereas gypsum dehydration results in a reversal back to anhydrite that leads to 39% volume decrease. Swelling and compressibility problems are common in several coastal deposits of the globe. This paper investigates the geological and engineering aspects of anhydrite/gypsum transition in the Arabian Gulf coast. Oedometer test results on Dammam anhydrite were studied in conjunction with morphological assessments at critical volume change stages. Results indicated 10% swelling potential and 295 kPa swelling pressure for hydrating anhydrite. The compression index of anhydrite and gypsum were 0.067 and 0.12, respectively, whereas the rebound index of anhydrite was 0.023.      

石膏晶型对水泥性能的影响机理研究

通过设计硬石膏替代不同比例的二水石膏系列实验,借助X射线粉末衍射仪(XRD)与电子扫描显微镜(SEM),研究了石膏晶型对水泥性能的影响,并对其影响机理进行了探究.结果表明:石膏的晶体差异导致了水泥强度的不同,掺入硬石膏的水泥强度较二水石膏的好;掺入硬石膏的水泥石形成的针状的钙矾石不仅对强度无影响而且可以填补水泥石的裂缝,从而增加了水泥石的密实度,而掺入二水石膏的水泥水化生成的柱状钙矾石晶体过大而且密,使水泥石产生较大的毛细裂缝,进而导致掺入二水石膏的水泥强度比较低.