Improvement of cement strength by induction method

The induction method of improriug the strength of Portland cement by adding fine slag powder,high aluminate component and hydrated poste was imestigated through determining the physical properties, hydration heat and pore size distribution, and its mechanism was discussed. The experimental results reveal that a certain content of high aluminate component,fine slag powder and hydrated paste can improve remarkably the strength of Portland cement.     

钢渣-矿渣-水泥复合胶凝材料的水化性能和微观形貌

通过测定矿渣和钢渣部分取代水泥构成的钢渣-矿渣-水泥复合胶凝材料(SBC-CCM)的物相组成和80h内的水化热,研究了SBC-CCM试样的微观形貌和水化性能,并用正交试验结果分析了SBC-CCM中钢渣-矿渣的最佳掺量和比例。结果表明:SBC-CCM的水化过程和水化产物的物相组成与硅酸盐水泥的相似,矿渣在水化早期参与反应,钢渣在水化早期呈惰性;SBC-CCM的80h水化放热量和放热速率均低于水泥相应的数值;正交试验结果表明水胶比对SBC-CCM强度的影响最显著,矿渣-钢渣的最佳质量比为2∶1。     

Strength of limestone-based non-calcined cement and its properties

A new type of cement was prepared with ground limestone powder, blastfurnace slag, steel slag and gypsum without calcination. The fraction of ground limestone powder in the cement was as high as 40 wt%–60 wt% without Portland clinker. All of its physical properties can meet the requirements of masonry cement standards. The impact of limestone content on physical properties of the cement and determined its impact on law was investigated. The steel slag can excit the aquation activity of this cement effectively, and the influence of its quantity on the strength of the materials was studied, which shows that the optimum quantity of mixing is 10%. By way of changing the different content of the lime stone by quartzy sample, the law of the compression strength and the PH value was determined, confirming that the lime stone can promote the early aquation of the slag and improve the early strength. The main hydration product of this cement is calcium aluminate hydrate, ettringite and calcium silicate hydrate, as indicated by XRD and SEM analysis.     

Hydration kinetics of phosphorus slag-cement paste

Hydration characteristics of Portland cement paste with phosphorus slag powder incorporated and hydration kinetics was investigated with SEM, X-ray diffraction, DTA-TG and calorimeter II 80. Results showed that phosphorus slag powder could reduce total amount of hydration products yet had little influence on the type of hydration products. The total amount of heat of hydration was decreased by 49.11% and the final setting was postponed by 2.28 h when phosphorus slag powder substituted 35% Portland cement by mass. The accelerating stage of this composite paste was controlled by catalysis, decreasing stage controlled by both catalysis and diffusion while stabilizing stage by diffusion alone. Hydration resistance and activation energy were reduced and hydration speed was accelerated.     

The Properties of Cement Mortars Modified by Emulsified Epoxy and Micro-fine Slag

1　IntroductionDuetotheirexcellentworkability ,highcompressiveandtensilestrength ,goodimpermeability ,highcorrosion-resistingperformancesagainstacid ,alkaliandsalt,thecement basedmaterialsmodifiedbypolymershaveratherwideapplicationfields .Amongthevariouspolymers ,epoxyresinhasmanyadvantages :(1)Highbondingstrength .Fattygrouphydroxyl,etherandepoxy based ,areinvolvedinthemolecularstructureofepoxyresin .Thepolaritiesofhydroxylandethercauseelectromagnetismorchemicaladsorptionbetweentheepoxyresin…     

Recycling of industrial waste and performance of steel slag green concrete

Workability and mechanical properties of steel slag green concrete with different types of steel slag and different dosages of admixtures were investigated. The effectiveness of steel slag powder on suppressing alkali aggregate reaction (AAR) expansion was assessed using the method of ASTM C441 and accelerated test method. Experimental results show that mechanical properties can be improved further due to the synergistic effect and mutual activation when compound mineral admixtures with steel slag powder and blast-furnace slag powder are mixed into concrete. In addition, about 50% decrease in expansion rate of mortar bars with mineral admixtures can be achieved in AAR tests. Mineral admixtures with steel slag powder as partial replacement for Portland cement in concrete is an effective means for controlling expansion due to AAR.     

Sr、Cs在碱矿渣-粘土复合水泥水化物粉体中的吸附行为

水泥的水化物对核索离子吸附性能将影响水泥固化体对核索离子固化性能。应用静态吸附法研究碱矿渣一粘土复合水泥（AASCM）水化物粉体对模拟放射性核素Sr、Cs的吸附性能及其影响因素，并和硅酸盐水泥（Pc）、铝酸盐水泥（AC）、矿渣硅酸盐水泥（PSC）、碱矿渣水泥（AASC）进行对比。结果表明，实验条件下，母液浓度提高，AASCM水化物粉体对Sr、Cs的吸附量增大，吸附比减小；温度升高，吸附平衡时间缩短，吸附量和吸附比下降。Cs在AASCM粉体中的吸附在一定的浓度范围内服从Freudlich吸附等温方程；AASCM水化物粉体与Sa^2＋的作用在母液浓度较大时存在吸附和沉淀双重机制，与Cs^＋的作用则主要是吸附机制；AASCM水化物粉体较PC、AC、PSC、AASC具有更强的吸附能力。     

冶金渣制备生态型人工鱼礁混凝土的试验研究

通过正交试验研究了矿渣钢渣熟料石膏体系胶凝材料的强度。胶凝材料正交试验表明：矿渣：钢渣的复合比为7∶1,矿渣和钢渣的比表面积分别为480 m 2·kg -1和550 m 2·kg -1,并与10%的水泥熟料和10%的脱硫石膏复合的胶凝材料具有较高的强度。以优化后的胶凝材料代替水泥,并以热闷法稳定化的钢渣颗粒为骨料,可以制备出抗压强度达到65 MPa以上的人工鱼礁混凝土。利用XRD和SEM方法分析胶凝材料的水化过程,结果表明,水化反应主要生成AFt相和C-S-H凝胶,钢渣、水泥熟料和脱硫石膏的协同作用对矿渣的火山灰活性反应具有重要促进作用。     

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.     

不掺硅粉的活性粉末混凝土配合比试验

在遵循活性粉末混凝土(RPC)基本配制原则的基础上,不掺入硅粉,采用超细水泥、普通水泥、掺合料(粒化高炉矿渣和粉煤灰)、砂、水、减水剂、钢纤维进行配合比试验。试验结果表明:不采用硅粉制备RPC是可行的;在制备RPC时,将超细水泥与适量掺合料混掺后,可以在保证材料强度和流动性的同时提高材料的经济性;用普通水泥取代大部分超细水泥后,材料的性能仍可保证,且更加经济。另外,研究了钢纤维掺量对材料性能(抗压、抗折、流动性及弯曲韧性)的影响规律。     

Resource utilization of slag from desulphurization and slag skimming: A comprehensive recycling process of all components

In order to make the slag from desulphurization and slag skimming (SDSS) to be comprehensively recycled and utilized, a combined process of beneficiation and building materials preparation was proposed to recover iron from SDSS, meanwhile to apply the remaining slag tailings as cement admixture. From this process, three iron-rich products were recovered in stages by clean gravity - magnetic separation, slag tailings were left. Slag powder was prepared by ultrafine grinding of slag tailings. The stability, setting time and cement mortar strength of the slag tailings cements (STC) which were mixed with Portland cement and slag powder were studied respectively. The results showed that a proper overall performance still could be obtained at the slag powder content of 30%. Chemical composition analysis, X-ray diffraction (XRD) analysis, metallographic microscope and scanning electron microscope (SEM) analysis were employed to assess the characteristics of the SDSS and the products obtained from the whole process. The results indicated that the three iron-rich products could be used as a raw material for steelmaking and ironmaking and the relatively large amount of calcium silicate (C₂S) and tricalcium silicate (C₃S) in the slag tailings make the addition of slag powder into the Portland cement feasible.     

The influence of steel slag with high Al2O3 content on the initial hydration of cement

The initial hydration of steel slag with high Al₂O₃ content and its influence on the initial hydration of cement were investigated in this study. Steel slag with high Al₂O₃ content may contain much calcium aluminate mineral but very little gypsum. The steel slag hydrates much more quickly than cement in the initial hydration period, producing many flake products which have a great influence on the fluidity, initial setting time, and adsorption level of superplasticizer of paste. Replacing part of cement by steel slag with high Al₂O₃ content can change the hydration condition of calcium aluminate mineral of the cement by decreasing the gypsum to calcium aluminate mineral ratio, resulting in accelerating the hydration rate of calcium aluminate mineral in the initial hydration period. Paste containing steel slag with high Al₂O₃ content has a shorter initial setting time, higher adsorption level of superplasticizer, and greater loss in fluidity than the pure cement paste.     

锰渣微粉-石灰石粉作为水泥混合材的试验

以锰渣微粉和石灰石粉按照不同比例进行复掺,研究其物理性能及水化性能。结果表明：锰渣微粉-石灰石粉可以有效减小标准稠度用水量,缩短水泥凝结时间,并且在水泥水化过程中能够很好地发挥其物理、化学综合性能,保证水泥早期和后期的强度。     

活性粉末混凝土的强度影响因素试验研究

基于已有理论研究,采用42.5普通硅酸盐水泥、矿渣、硅灰、高效减水剂、消泡剂以及标准砂等原料,进行活性粉末混凝土的配制试验.为了得到比较合理的配合比,制作了多组试件供试验,并研究了不同水胶比、砂胶比、外加剂掺量、钢纤维掺量对于活性粉末混凝土抗压强度和抗折强度的影响.在保证活性粉末混凝土性能的前提下,探究采用常见材料的活性粉末混凝土配合比.     

Methods for improving volume stability of steel slag as fine aggregate

Suitable methods for enhancing the volume stability of steel slag utilized as fine aggregate were determined. The effects of steam treatment at 100 ℃ and autoclave treatment under 2.0 MPa on the soundness of steel slag sand were investigated by means of powder ratio, linear expansion, compressive and flexural strength. DTA, EDX, XRD and ethylene glycol methods were employed to analyze both the treated slags and susceptible expansion grains. Experimental results indicate that powder ratio, content of free lime and rate of linear expansion can express the improvement in volume stability of different treated methods. Steam treatment process cannot ultimately prevent specimens from cracking and decrease of strength, but mortar made from autoclave treated slag keeps integration subjected to hot water of 80℃ until 28 d and its strength do not show significant decrement. The hydration of over-burn free lime and periclase phase are the main cause for the disintegration or crack of untreated and steam treated steel slag＇s specimens. Autoclave treatment process is more effective than steam treatment process on enhancement of volume stability of steel slag.     

钢渣改良膨胀土试验效果与机理分析

对膨胀土、石灰改良膨胀土、钢渣微粉改良膨胀土进行干湿循环试验、自由膨胀率试验、无侧限抗压强度试验,比较验证钢渣微粉对膨胀土的改良效果。试验结果表明:钢渣微粉对膨胀土干湿循环作用下裂隙的发展、自由膨胀率的减小、强度的增加均有明显改善效果。其中钢渣微粉对自由膨胀率的改良效果明显滞后于石灰,但最终的改良效果两者相近,强度改良效果钢渣微粉明显优于石灰。同时运用X射线能谱的方法对膨胀土、石灰改良膨胀土、钢渣微粉改良膨胀土进行矿物成分和化学组成分进行分析,发现钢渣微粉改良膨胀土与石灰改良膨胀土矿物成分相近结合,自由膨胀率和无侧限抗压强度试验结果,对比分析得出钢渣微粉改良膨胀土和石灰改良土在改良机理上有相似性。     

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…     

Model Analysis of Initial Hydration and Strueture Forming of Portland Cement

The auto efficiently hydration heat arrangement and the non-contacting electrical resistivity device were used to test the thermology effect and the resistivity variation of Portland cement hydration. The structure forming model of Portland cement initial hydration was established through the systematical experiments with different cements,the amount of mixing water and the chemical admixture.The experimental results show that,the structure forming model of cement could be divided into three stages,i e,solution-solution equilibrium period,structure forming period and structure stabilizing period.Along with the increase of mixing water,the time of inflexion appeared is in advance for thermal process of cement hydration and worsened for the structure forming process.Comparison with the control specimen,adding Na_2SO_4 makes the minimum critical point lower,the flattening period shorter and the growing slope after stage one steeper.So the hydration and structure forming process of Portland cement could be described more exactly by applying thc thermal model and the structure-forming model.     

Model Analysis of Initial Hydration and Structure Forming of Portland Cement

The auto efficiently hydration heat arrangement and the non-contacting electrical resistivity device were used to test the therrnology effect and the resistivity variation of Portland cement hydration. The structure forming model of Portland cement initial hydration was established through the systematical experiments with different cements, the amount of mixing water and the chemical admixture. The experimental results show that, the structure forming model of cement could be divided into three stages, i e, solution-solution equilibrium period, structure forming period and structure stabilizing period. Along with the increase of mixing water, the time of inflexion appeared is in advance for thermal process of cement hydration and worsened for the structure forming process. Comparison with the control specimen, adding Na2SO4 makes the minimum critical point lower, the flattening period shorter and the growing slope after stage one steeper. So the hydration and structure forming process of Portland cement could be described more exactly by applying the thermal model and the structure-forming model.     

硅酸盐水泥水化历程与初始结构形成的研究

采用自动高效水化热测定仪及无电极电阻率测定仪研究硅酸盐水泥水化的热学效应及交变电场下电阻率变化，讨论水泥品种、拌和水量对水泥水化初始结构形成及发展的影响，建立硅酸盐水泥水化初始结构形成及发展的结构形成模型。研究表明：初始结构形成模型分为3个阶段：溶解-溶解平衡期、结构形成期及结构稳定期。随着水量的增大，水化热效应表现为促进作用，但是结构形成过程表现为结构弱化；电阻率曲线的特征值及时间数值随水泥品种不同而变化。水化热模型与结构形成模型相结合，可以准确描述水泥初始水化历程及结构瞬时形成状态。