Effects of Curing Systems on Properties of High Volume Fine Mineral Powder RPC and Appearance of Hydrates

The effects of different curing systems on the properties of high volume fine mineral powder RPC （reactive powder concrete） and the appearances of hydrates were studied. The experimental results show that dry-heating curing promotes the development of pozzolanic reactivity of fine mineral powder; due to low cement content, 0.20 water-bind ratio and high reactive fine mineral powder content, the strength of RPC increases by around 200% after steam curing and subsequent dry-heating curing. Scanning electron microscopy and energy spectrum diagram showed that： after the high volume fine mineral powder RPC with 0.16 water-bind ratio underwent steam curing and dry-heating curing, there was no significant change in the appearance of hydrates; after the RPC with 0.20 water-bind ratio, the cement content of 150 kg/m3 and more steel slag powder underwent dry-heating curing, there was a certain change in the appearance of C-S-H, the structure of gel was more compact and was uniformly distributed, and the Ca/Si of C-S-H gel decreased from 1.41 to around 1.20.

Influence of MnO_2 Mineralizer on the Crystal Structure,Properties of SiC Kiln Furniture Bonded with Fine Silicon Powder

The properties of SiC kiln furniture bonded with fine silicon powderare related to the bonder’s crystal structure. At high temperature, it will crystallize ina-cristobalite with great bulk effect. MnO2 mineralizer can make a-cristobalite convertto a-tridymite whose bulk effect is small. The crystal structure and its amount were investigated with XRD technique. The influence of different amounts of MnO2 on thecrystal structure and polycrystal transformation, and that of crystal structure on theproperties of kiln furniture were studied. The best proportion of MnO2 added was determined to be 2.0%.

Expansion Performance and Microstructure of High-performance Concrete using Differently Scaled MgO Agents and Mineral Powder

To investigate the assumptions proposed in this paper,the evolution law governing the strength and expansion performance of MgO and nano-MgO micro-expansive concrete in the environment of mineral powder was firstly observed in this study.Secondly,SEM,XRD,and TG-DSC microscopic tests were conducted to reveal the effects of the active mineral-powder admixture on the hydration degree and expansion performance of MgO and nano-MgO in HPC.Our experimental results successfully verified our hypothesis,which indicated that the expansion performance of macro-MgO and nano-MgO was indeed depressed by the addition of active mineral power admixtures,even though the mechanical property of concrete composites was effectively improved.Furthermore,the hydration test also demonstrated the negative interference on the mineral powders,which was induced by the expansion agents.It is found the amounts of hydrates tend to decrease because the mineral powder ratio reaches and exceeds 40%.Moreover,it is also concluded the effect of expansion agents is governed by the alkalinity cement paste,especially for the nano-MgO.In other words,the expansion performance of nano-MgO will vary more obviously with the hydration process,than MgO.The results of this study provide that effective experimental and theoretical data support the hydration-inhibition mechanism of magnesium expansive agents.

The Influence of Mesoscopic Characteristics of Mineral Powders Fillers on the Rutting Factor(G^(*)/sinδ)of Asphalt Mortar

This study aims to investigate the efiect of the mesoscopic characteristics of mineral powder fillers on the rutting resistance of asphalt mortar.Extraction and sieving tests were used to obtain the buton rock asphalt(BRA)ash with particle size smaller than 0.075 mm,which is consistent with that of the conventional mineral powder.The mesoscopic characteristics of BRA ash and conventional mineral powder were measured by SEM image analysis and the osmotic free pressure water method.Mesoscopic structure models of structural and free asphalts in mortar were obtained.The 70#matrix asphalt was used to prepare two kinds of asphalt mortar with BRA ash and conventional mineral powders fillers.The rutting factor of the two asphalt mortars was tested by dynamic shear test(DSR).Test results show that the ash extracted from BRA has a similar mesoscopic classification with the conventional mineral powder.Still,its fractal dimensions are larger,indicating the particles in BRA ash have more complex shapes and rougher surfaces,which is beneficial for forming structural asphalt and subsequently increasing the rutting factor(G*/sinδ),i e,improving the rutting resistance of the asphalt mortar.

Effect of Substitution of Cement by Mineral Powders on the Physico-mechanical Properties and Microstructure of Sand Concretes

The approach that contributes to the development of eco-materials in construction is the use of mineral powders,which can improve mechani­cal properties and reduce cement consumption.This article aims to study the effect of substitution by mass of cement with mineral powders on the physicomechanical properties and microstructure of sand concretes.The used mineral powders are A:the limestone,B:the natural pozzolan,C:the hydraulic lime,D:(1/3 limestone+1/3 natural pozzolan+1/3 hydraulic lime),and E:(1/2 natural pozzolan+1/2 hydraulic lime).The studied percentages are 5%,10%and 15%,in both separated and combined states.The studied properties are workability,compressive strength,the elastic­ity modulus in compression,shrinkage and microstructure analysis.The objective is to target the optimal percentage of the substitution of cement with mineral powders,which ensures the best compromise between the main properties of the studied sand concretes.The obtained results show that the optimal percentage is in favor of the substitution of cement by 10%D(1/3 limestone,1/3 natural pozzolan and 1/3 hydraulic lime).Even the 15%of mineral powder D,presented similar performances compared to the sand concrete(without mineral powders).Finally,in the context of the development of eco-materials,it should be noted that the 10%D and 15%D(1/3 limestone,1/3 natural pozzolan and 1/3 hydraulic lime)contribute to decrease the use of cement and consequently to reduce of CO2 emissions.

沙漠砂混凝土力学性能试验研究

研究了不同沙漠砂单掺、沙漠砂-矿渣粉复掺以及沙漠砂-矿渣粉-钢纤维三掺量对沙漠砂混凝土(Desert Sand Concrete, DSC)抗压强度、劈裂抗拉强度的影响,结果表明,随着沙漠砂掺量的增加,混凝土的抗压强度先增加后减小,当掺量为20%时达到最佳状态;矿渣粉掺量20%时显著提高了混凝土的强度;钢纤维掺量在0.8%时对抗压强度和劈裂抗拉强度的提升效果最为显著。沙漠砂、矿渣粉钢纤维的加入能够改善混凝土的孔隙结构,钢纤维的桥接作用有效阻止裂缝扩展,对增强材料韧性最为显著。

Effect of High Content Limestone Powder on Microstructure and Mechanical Properties of Cement-based Materials

Compared with the control sample without limestone powder(LP), the mechanical properties of the sample with 30% LP can be significantly improved by using a small amount of water reducer to reduce the water-cement ratio, without significantly affecting the fluidity of the fresh mixture and increasing the economic cost. In addition, compared with the sole addition of limestone powder, dual addition of metakaolin and limestone powder can effectively improve the strengths. The reason of this phenomenon was investigated by means of XRD, TG-DTG, SEM, LF-NMR and isothermal calorimetry, etc. The reactive aluminum-rich phases in metakaolin react with limestone powder in the hydration process, and the formed calcium carboaluminate reduces the porosity and makes the hardened paste denser. The addition of ground granulated blast furnace slag can also improve the strength of the specimen added with limestone powder, whereas, the effect is inferior to that of metakaolin, for the ground granulated blast furnace slag contains less reactive aluminate phases, and accordingly, the amount of calcium carboaluminate generated is lower than that of metakaolin.

钢渣复合矿粉对不同养护条件下混凝土性能的影响

为了探讨利用钢渣和矿渣制备复合掺合料的可行性,按质量比3∶7将钢渣与矿渣进行共同粉磨,制备复合矿粉,研究了复合矿粉对不同养护制度下混凝土的工作性和力学性能的影响,并对水化产物进行了表征。结果表明,复合矿粉使混凝土1 h的坍落度损失下降了6.9%,表现出了较好的保坍效果;在20℃标准养护和60℃蒸汽养护下,掺复合矿粉混凝土的立方抗压和轴向抗压强度与对照组相比均有所提高,但掺复合矿粉混凝土的劈裂抗拉强度均略低于对照组。微观分析发现,复合矿粉的掺入,使得生成的水化硅酸钙氧硅比降低,聚合度增加;水泥石总孔隙率由26.34%下降到23.99%;促进生成更多的水化产物。研究表明,在矿粉中掺入适量的钢渣粉制备复合矿粉具有较高的可行性,是同时实现钢渣和矿渣资源化利用的有效途径。

矿粉微观特征及其与沥青胶浆流变性能的灰度分析

为探究矿粉的物理特征及微观结构,深入研究胶浆流变性能及矿粉对胶浆性能的影响,分析了不同类型矿粉的物理特性、化学组成及微观结构,采用不同类型矿粉及不同0.075 mm筛孔通过率矿粉制备不同掺量的沥青胶浆,利用动态剪切流变与弯曲梁流变试验对不同矿粉沥青胶浆的高低温流变性能的影响规律进行分析,借助灰色关联分析法分别探究矿粉的物理参数、微观结构参数与沥青胶浆高温、低温性能之间的关联性。试验结果表明:5种矿粉的微小孔隙数量较少,R3与R4矿粉的孔隙多为狭长型,R1、R2、R5矿粉的孔隙多是颗粒堆积形成的;随矿粉掺量的增加,沥青胶浆的整体高温性能和抗流动能力越好,而低温性能先减弱后增强;将比表面积等指标作为比较数列,相位角等指标作为参考数列,利用灰色关联分析法确定氧化物含量对高温性能影响最大,矿粉比表面积影响最小;低温条件下,矿粉粒度对蠕变劲度影响最大,平均孔径对蠕变劲度变化率影响最大。对矿粉指标的控制及其高低温特性变化的研究结果可为实际工程应用提供参考。

三元矿物掺和料胶砂试件性能研究

为解决煤矸石及钢渣作为单一掺和料强度不足的问题,以煤矸石、钢渣和矿粉为原材料制备复合掺和料水泥砂浆。研究不同配合比下掺和料对水泥砂浆抗压强度的影响,并利用X射线衍射(XRD)、热重-差热分析(TG-DTA)、扫描电镜(SEM)等手段分析不同体系试块的水化机理和微观结构。结果表明,单掺煤矸石、钢渣均表现出较低的活性,而矿粉具有良好的反应活性;三元掺和料中煤矸石-矿粉-钢渣复掺比例为1∶7∶2时,试块的抗压强度最高,28 d抗压强度可以达55.26 MPa。在三元掺和料体系中,煤矸石、矿粉和钢渣可以相互促进水化,增多水化产物,加深水化程度,三者具有一定的耦合作用,具有制备三元矿物掺和料的潜力。

粉体表面改性课课程思政建设与教学改革探索

矿物加工工程专业人才培养是保障国家能源安全与社会经济建设人才战略的关键环节,而矿物加工工程专业课程融入思政元素则是当前人才培养过程的重要模式。在思政和专业教育全面融合的背景下,该文以粉体表面改性课程为例,初步总结和探讨课程思政在矿物加工工程专业人才培养过程中的思政元素、教学方法与载体途径,以及教学效果评价体系,以期提升学生培养质量,培育新时代具备“科学观、工程观、全局观”等学科基础知识和理论、创新实践能力强的矿物加工工程专业人才,从而为保障矿产资源安全和社会可持续发展提供有力支持。

矿物掺合料在活性粉末混凝土(RPC)中应用研究

矿物掺合料作为一种重要材料在混凝土中应用,为研究矿物掺合料对活性粉末混凝土(RPC)性能影响,以及应用的可行性,将矿物掺合料复配到C120 RPC中,研究对RPC的性能影响规律及得到最佳胶凝材料体系。结果表明:(1)最小基本需水量、标准稠度需水量试验得到矿物掺合料最佳掺量,水泥∶超细矿粉∶硅灰∶粉煤灰=0.7∶0.1∶0.1∶0.1。(2)超细矿粉对RPC 3 d、7 d强度影响明显,分别最大提高6 MPa、13.5 MPa;硅灰对RPC 28 d强度影响明显,最大提高2.2 MPa;粉煤灰对RPC扩展度影响明显,最大提高71 mm。(3)研究确定RPC中四元胶凝体系,即水泥∶超细矿粉∶硅灰∶粉煤灰=0.7∶0.1∶0.1∶0.1,RPC坍落度370 mm,扩展度615 mm,28 d抗压强度128.47 MPa,抗硫酸盐侵蚀等级KS90。

CFB飞灰压浆料的制备及高强微膨胀机理研究

利用循环流化床燃煤固硫灰(CFB飞灰)的活性与膨胀性制备压浆料,研究了CFB飞灰掺量和水胶比对压浆料工作性能、强度和膨胀率的影响;CFB飞灰与矿粉以不同比例复配,对比研究了CFB飞灰压浆料的高强微膨胀特性,并采用XRD与SEM分析验证。结果表明,随CFB飞灰替代水泥掺量的增加,压浆料的需水性增强,抗压强度降低,20%(质量分数)CFB飞灰的试样28 d抗压强度与基样接近,可达85.8 MPa,而抗折强度先升高后降低,膨胀率一直升高。随用水量的增加,压浆料的膨胀率降低但均为正值。随CFB飞灰取代矿粉率的提高,压浆料的工作性能降低,28 d抗压强度先升高后降低,其中20%(质量分数)CFB飞灰、10%(质量分数)矿粉复合的试样28 d抗压强度最高,为99.8 MPa,膨胀率一直升高。通过CFB飞灰与矿粉复合配制了各项性能均满足铁标要求的压浆料。CFB飞灰不仅自身水化产生膨胀,还能激活矿粉活性,产生复合增强作用。

基于粉煤灰和矿粉作为掺合料的无砟轨道自密实混凝土性能对比分析

随着中国高速铁路的快速发展,无砟轨道自密实混凝土在高速铁路建设中的应用越来越广泛。为了提高无砟轨道自密实混凝土的性能,粉煤灰和矿粉作为两种重要的混凝土掺合料被广泛使用。文章将对这两种掺合料在无砟轨道自密实混凝土中的应用进行对比分析,旨在为工程实践提供有益的参考。

参骨方对脾虚湿困型老年骨质疏松性骨折患者术后疗效影响研究

【目的】观察参骨方颗粒剂(以参苓白术散合四妙散为基础方进行加减)对脾虚湿困型老年骨质疏松性骨折患者术后疗效、中医证候、骨折愈合及骨密度的影响。【方法】将80例脾虚湿困型老年骨质疏松性骨折患者随机分为治疗组和对照组,每组各40例。对照组给予服用骨化三醇胶囊治疗,治疗组在对照组的基础上给予参骨方颗粒剂治疗,疗程均为8周。观察2组患者治疗前后中医证候积分、骨密度值及骨代谢指标的变化情况,并比较2组患者的骨折愈合时间及术后疗效。【结果】(1)疗效方面,治疗8周后,治疗组的总有效率为87.50%(35/40),对照组为67.50%(27/40),组间比较,治疗组的疗效明显优于对照组(P<0.05)。(2)中医证候积分方面,治疗后,2组患者的中医证候积分均较治疗前明显下降(P<0.01),且治疗组对中医证候积分的下降幅度明显优于对照组(P<0.01)。(3)骨代谢指标方面,治疗后,2组患者的血清骨钙素(OC)水平均较治疗前明显升高(P<0.05),血清Ⅰ型原胶原氨基端前肽(PINP)水平均较治疗前明显下降(P<0.05);而血清β-胶原交联羧基端肽(β-CTX)水平方面,治疗组患者较治疗前明显下降(P<0.05),对照组患者较治疗前有下降趋势,但差异无统计学意义(P>0.05);组间比较,治疗组对血清OC水平的升高幅度及对血清PINP、β-CTX水平的下降幅度均明显优于对照组(P<0.05)。(4)骨密度值方面,治疗后,2组患者的骨密度值均较治疗前明显升高(P<0.05),且治疗组对骨密度值的升高幅度明显优于对照组(P<0.05)。(5)骨折愈合时间方面,经过8周治疗后,治疗组患者的股骨骨折、桡骨骨折、胫骨骨折、肱骨骨折的骨折愈合时间均较对照组明显缩短(P<0.05)。【结论】参骨方颗粒剂可显著改善脾虚湿困型老年骨质疏松性骨折患者的术后临床症状和脾虚湿困症状,改善骨代谢,促进骨质疏松性骨折的愈合。

水工混凝土掺合料特性及石灰石粉水化机理研究

利用扫描电镜、X射线衍射、压汞等材料分析手段,系统研究了石灰石粉、粉煤灰、磨细矿渣三种水工混凝土常用掺合料的矿物组成、表面特性,以及二元、三元胶凝材料体系的水化机理。结果表明,石灰石粉颗粒表面粗糙,促进水泥早期水化,微弱参与反应并生成水化碳铝酸钙,但不具有火山灰活性,石粉对水泥石中孔径在20~100 nm范围的孔隙影响较大,提高石粉掺量,该范围的孔隙增多,硬化浆体孔结构变差。粉煤灰中含有大量的球形颗粒,颗粒表面致密光滑,含有大量玻璃体,将粉煤灰与石粉复合双掺,粉煤灰的火山灰效应能够优化浆体孔结构。

Industrial mineral powder production in China

The recent annual output of major industrial mineral powders in the mainland of China has been more than 100 million t, accompanied by active development of such supporting technology as comminution, classification, separation/purification, and surface modification. In particular, the present paper reviews technologies for preparing ultra-fine particles involving dry and wet processing, modification and composition, calcination of kaolin clay, and processing of spherical/acerous industrial minerals.

矿粉改性高性能混凝土的力学性能和耐久性能研究

以S115矿粉为掺和料,制备了矿粉改性高性能混凝土,通过XRD、SEM、复合盐溶液干湿循环测试等手段,分析了矿粉取代率对混凝土的晶格结构、微观形貌、力学性能和耐久性能的影响。结果表明,适量矿粉的掺入能够加速水泥的水化反应速率,增加网格结构的致密度,从而改善混凝土的微观形貌,提高混凝土的强度。矿粉取代率的增大会降低水泥石前期的强度,显著提高水泥石后期的强度。当矿粉取代率为50%时,养护28 d的混凝土的抗压强度和抗折强度均达到了最大值,分别为52.5和7.4 MPa。矿粉取代水泥后,混凝土在复合盐溶液的侵蚀下相对动弹性模量和质量损失率的下降趋势变得平缓,在30次干湿循环后,矿粉取代率50%的混凝土的相对动弹性模量最高为88%,质量损失率最小为1.6%,抗盐溶液侵蚀性能最佳。混凝土的腐蚀产物主要是针状结构的钙矾石和块状的石膏,这些产物存在于混凝土的孔隙和裂纹中,多次干湿循环后体积膨胀产生了内部应力,生成了深裂纹,最终撑裂混凝土,使混凝土失效。综合可知,矿粉的最佳取代率为50%。

Biotransformation of Earthworm Activity on Potassium-Bearing Mineral Powder

This study analyzes the biotransformation of earthworms on K in potassium-bearing mineral powder （PBMP） under different PBMP recruitments. A mixture of PBMP （10% to 60% mass fraction） and decaying cow dung was used as feed for breeding the earthworms to study the potassium-releasing ability of earthworms on PBMP in soil. The mixture containing 20% and 30% PBMP resulted in good growth and propagation of the earthworms as well as higher conversion rates of potassium. Therefore, the optimum recruitments of mineral powder are 20% and 30%. The mixture of cow dung and PBMP was compared with the mixture of cow dung and corresponding proportions of quartz powder to analyze the conversion rate of earthworms on PBMP in different combinations. After the earthworms were raised with the mixture of cow dung and PBMP （8 ： 2 and 7 ： 3） for 30 d, the contents of rapidly available K and effective K were 10 824.3±35.9 and 11 688.4±16.1 mg.k-1 as well as 10 079.6±62.2 and 10 247.5±172.7 mg.kg-1, respectively. After the earthworms were raised with the mixture of cow dung and quartz powder （8 ： 2 and 7 ： 3） for 30 d, the contents of rapidly available K and effective K were 10 623.3±41.1 and 11 385.5±13.5 mg.kg-1 as well as 9 834.2±51.8 and 9 907.6±11.4 mg.kg-1, respectively. Thus, the contents of rapidly available K and effective K in the mixture of cow dung and PBMP were significantly higher compared with those in the mixture of cow dung and quartz powder （P〈0.05）. The increment contents of rapidly available K and effective K were 201.0 and 302.9 mg.kg1 as well as 245.4 and 339.9 mg-kg1, respectively. Therefore, earthworms can activate and trans-form K into effective K through feeding, digestion, absorption, and excretion. The results pro- vided a new idea of using earthworms to release potassium in low-grade potassium-bearing rocks and obtain the rapidly available K and effective K needed by plants.

矿粉和生石灰高温改性对磷石膏水泥基材料性能影响

由于磷石膏中杂质不可避免地掺入,导致磷石膏的质量较差,进一步阻碍了磷石膏的应用。通过使用磷石膏和硅酸盐水泥作为原料,探究生石灰高温改性磷石膏对水泥基材料强度的影响,进而研究矿粉对大掺量磷石膏水泥基材料强度不足和凝结过快等缺陷的改善效果,最后采用XRD和SEM分析了磷石膏水泥基材料的水化产物,探明生石灰和矿粉对磷石膏水泥基材料性能的改善机理。结果表明,生石灰在高温下可以成功地消除磷石膏中的酸性杂质,提升胶凝材料的强度,综合考虑环保性和强度性能,生石灰的最佳掺量为2%。矿粉的掺入可以进一步提高胶凝材料的强度,延缓磷石膏水泥基材料的初终凝时间,随着矿粉掺量的持续增加,胶凝材料在28 d时的强度呈现出先增大后减小的趋势。综合考虑各项性能,矿粉的最佳掺量为20%。此外,在掺加矿粉后,胶凝材料在28 d的微观形貌中生成了相互交织的水滑石,其结构稳定有利于磷石膏水泥基胶凝材料力学性能的发展。