The Influence of Free Water Content on Dielectric Properties of Alkali Active Slag Cement Paste

The dielectric performance of alkali activated slag （AAS） cement paste was investigated in the frequency range of 1 to 1000 MHz. The experimental results showed the unstable dielectric properties of harden paste were mostly influenced by the fraction of free water in paste or absorbed water from ambient, but not including hydration water and microstructure. The free water was completely eliminated by heat treatment at 105 ℃ about 4 hours, and then its dielectric loss was depressed; but with the exposure time in air increasing, the free water adsorption in ambient air made the dielectric property of harden cement paste to be bad. The temperature and relative humidity of environment was the key factors of free water adsorption; hence, if the influence of free water on dielectric constant was measured or eliminated, the cement-based materials may be applied in humidity sensitive materials or dielectric materials domains.     

砼碱集料反应及抑制措施

砼碱集料可对建筑物结构产生危害，特别在高层建筑中更加突出，本文通过工程实例，总结出本地区砼碱集料反应的特点和主要碱活性集料，提出抑制措施。     

Morphology difference between the alkali activated cement and portland cement paste on multi-scale

The features of alkali activated slag（AAS） and portland cement （PC） were observed on multi-scale,the crack and fracture sections were observed with naked eyes,and SEM and AFM were used to study the structure morphology differences between PC and AAS on micrometer to nano meter scale.The experimental results indicated that the AAS paste had soil like fracture texture and it was composed of mainly C-S-H gel but lacks of crystals,and it had a very strong tendency to shrink and crack.AAS paste is much denser and more homogeneous than PC,and on the nano scale C-S-H nano particle in the AAS paste is much smaller and packs much denser than PC paste.     

A Blended Cement Containing Blast Furnace Slag and Phosphorous Slag

Blended cement comaining blast furnace slag( BFS ) and phosphorous slag( PS) is a new kind of cement. The total content of blended materials could increase if two additives were used. Using the same admixtures , the properties of the blended cement with 70% additives could reach the standard of 525-grade slag cement according to GB. The strength of cement with 80% additives could reach the standard of 425-grade slag cement. The tests of strength, pore structure, hydration products, inhibiting alkali-aggregate reaction, resistance to sulfate corrosion of BFS-PSC were performed.     

高强型碱碳酸盐-矿渣胶凝材料的研究

在采用缓凝剂的基础上，研究了水玻璃模数(n)、浓度(CSS)以及矿渣替代碳酸盐矿质量分数(Ms)等对碱碳酸盐一矿渣胶凝材料性能的影响，并对该体系反应产物的微观形貌和胶砂试体的孔分布进行了分析。研究结果表明，当采用适宜的n、Cs和Ms时，材料3d和28d的胶砂体抗压强度可分别达到50MPa和90MPa以上，且随龄期延长而不断增长。     

Cl-渗透和碱集料反应作用下纳米混凝土的耐久性

海洋环境下,氯离子(Cl~-)渗透和碱集料反应是影响混凝土耐久性的重要因素.为此,在普通海工混凝土中掺加适量纳米SiO_2或纳米Al_2O_3,研究纳米混凝土在Cl~-渗透和碱集料反应共同作用下的耐久性.结果表明:Cl~-渗透和碱集料反应两种因素对混凝土耐久性的影响是相互促进的.不同掺量的纳米SiO_2或纳米Al_2O_3可以不同程度地抑制混凝土的Cl~-渗透和碱集料反应,提高混凝土在两种因素共同作用下的耐久性,纳米SiO_2和纳米Al_2O_3在混凝土中的最优掺量均为2. 0%. Cl~-总质量分数趋于平衡时,纳米SiO_2混凝土和纳米Al_2O_3混凝土的Cl~-总质量分数分别降低18. 04%和11. 60%;在第39周时,纳米SiO_2混凝土和纳米Al_2O_3混凝土的膨胀率分别降低28. 75%和16. 87%.纳米颗粒的加入能够改善混凝土的孔结构,提高混凝土的抗Cl~-渗透性,抑制Friedels盐的产生,从而减少混凝土的膨胀;此外,纳米颗粒能够促进水泥二次水化,降低过渡区Ca(OH)2晶体的富集程度,阻碍CaCl_2的络合物产生和碱集料反应所需碱环境的形成.     

高温历程对碱矿渣混凝土残余抗压强度的影响

为了探明高温历程对碱矿渣混凝土残余抗压强度的影响,对不同升温速率（5、10 ℃/min）、恒温时间（1、2 h）和冷却方式（自然冷却、浇水冷却）作用后的碱矿渣混凝土残余抗压强度进行表征,并通过胶凝材料基体微观结构的高温变化对上述强度变化进行分析。结果表明：升温速率较快的情况下,当温度低于400 ℃时,热应力影响不明显,由于受热时长较短,残余强度较高;随着温度升至800 ℃,热应力影响显著,混凝土残余强度持续显著降低;800 ℃之后,热应力达到一定程度,较短的受热时长保证了较高的残余强度。恒温时间的延长会加剧胶凝材料基体结构及基体-骨料界面过渡区的劣化效应,从而引起混凝土残余强度的降低。浇水冷却降低了水化产物C-S-H凝胶的分解温度,并在混凝土内产生热应力,残余强度损失明显。     

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.     

Setting and Strength Characteristics of Alkali-activated Carbonatite Cementitious Materials with Ground Slag Replacement

The effect of the ground granulated blast-furnace slag （ GGBFS ） addition, the modulus n （ mole rutio of SiO2 to Na2O ） and the concentrution of sodium silicate solution on the compressive strength of the material, i e alkuli-activated carbonatite cemeutitious material （ AACCM for short ） was investiguted. In addition, it is found that barium chloride has a sutisfiwtory retarding effect on the setting of AACCM in which more than 20% （ by mass ） ground carbonatite was replaced by GGBFS. As a result, a cementitious material, in which ground carbonatite rock served as dominative starting material, with 3-day and 28-day compressive strength greuter them 30 MPa and 60 MPa and with continuous strength gain beyond 90 days was obtained.     

The Mechanism of Ground Granulated Blastfurnace Slag Preventing Alkali Aggregate Reaction

Three different methods were applied to study the alkali content of gelpores in cement. In the closed system, the concentration of K+, Na+ and OH - have not reduced with the increase of age. In the open system, the diffusion and transferring of K+ and Na+ towards free space leads to the de-crease of total alkali content. In the micro-analysis system, the contents of K+ and Na+ in the first hy- drated layer of ground granulated blastfurnace slag (GBFS) are very low, while the contents of calcium and magnesiu...     

Optimization of Blended Mortars Using Steel Slag Sand

A new kind of mortar made of ground granulated blast-furnace slag （GGBFS）, gypsum, clinker and steel slag sand （〈4.75 mm） was developed. The ratio of steel slag sand to GGBFS was 1 ： 1 and the amount of gypsum was 4% by weight while the dosage of clinker ranged from 0% to 24%. The optimization formulation of such mortar was studied. The content of steel slag sand should be less than 50% according to the volume stability of blended mortar, and the dosage of clinker is about 10% based on the strength development. Besides strength, the hydration heat, pore structure and micro pattern of blended mortar were also determined. The experimental results show the application of steel slag sand may reduce the dosage of cement clinker and increase the content of industrial waste product such as GGBFS, and the clinker is also a better admixture for blended mortar using steel slag sand.     

Microstructure and Properties of Activated Slag Cement

Activation of the slag cement was performed using a composite activator. Experimental results show that the performance of the cement is remarkably improved. The fineness and specific surface area of the cement are increased by 23.7% and 1.4% , and 3d flexural strength and compressive strength are enhanced by 20.9% and 22.9%, respectitely. Microstructure and phase composition of the hydrates were analysed by X-ray diffraction( XRD ) and scanning electron microscopy( SEM ). The results indicate that Ca(OH)2 in the hydrates decrease obvioasly. The morphology of the other hydrates appears to be flocculent, with a dense structure. The improvements of the properties is related to the microstructural changes.     

水泥与偏高岭土地聚物砂浆碱骨料反应对比研究

为减少环境污染,近年来对碱激发胶凝材料的研究逐渐增加,而目前研究大多集中在地质聚合物机理方面,较少涉及其碱骨料反应。本文试图探究高温高碱环境下,碱激发胶凝材料砂浆与传统水泥砂浆碱骨料反应的不同,以推进碱激发胶凝材料的工程应用。通过测量试件不同龄期长度变化,研究掺不同骨料的水泥砂浆和偏高岭土基地聚物砂浆在高温高碱溶液中的变形行为,同时采用XRD、SEM等微观手段分析二者不同龄期产物的组成和微观结构。研究结果表明：地聚物与水泥的碱骨料反应历程存在明显区别,地聚物中不会发生严重的碱骨料反应,工程中能使用碱活性强的骨料;地聚物浆体最终形成(类)沸石结构,其笼式结构能吸附和固溶大量有害碱,能适应海工等强腐蚀性环境。     

掺矿粉水泥的水化机理研究

研究利用在硅酸盐水泥中掺加矿粉来提高水泥的抗折强度,降低脆性,并通过ＴＧ－ＤＴＡ、Ｘ－衍射及ＳＥＭ等微观分析方法对掺矿粉水泥的水化机理进行研究,结果表明,矿粉的掺入不权可以提高水泥的水化程度,增加水泥石的密实度,同时也可以降低水泥石的脆性。     

石英玻璃在不同碱性条件下的硅溶出研究

采用电感耦合等离子发射光谱法(Inductively Conpled Plasma Atomic Emission Spectra,简称ICP-AES)系统测试了石英玻璃在不同碱性条件下的硅溶出情况．结果表明：在单一或混合碱性溶液中,石英玻璃中的硅溶出表现出较为一致的规律,即：石英玻璃中的硅在NaOH或KOH条件下的溶出量远远大于相同条件下的HOH溶液;相比而言,硅在NaOH溶液中的溶出量大于其在KOH溶液中的溶出量．在相同条件下,LiOH表现出与NaOH、KOH不同的性质特征,这为锂盐抑制碱集料反应的作用机理提供了一定的证据．     

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…     

平炉钢渣配制水泥的研究

分析了钢渣的组成，介绍了钢渣利用的可能途径，提出了用平炉钢渣作为普通硅酸盐水泥水硬性混合材综合利用的方案．     

砂岩骨料的碱活性检测与抑制试验

用岩相法、砂浆棒快速法、溶胶-凝胶膨胀法和混凝土棱柱体法,联合研究了砂岩骨料的碱硅酸反应(ASR)活性,评价了粉煤灰对该砂岩ASR膨胀的抑制效果.试验结果一致表明了该砂岩骨料具有潜在的ASR活性,其碱活性主要来自于玉髓状微晶石英和波状消光石英.采用20%的Ⅰ级粉煤灰替代水泥,可以把这种砂岩的ASR膨胀量控制在非碱活性范围之内.     

低活性矿渣内养护水泥砂浆自收缩与电阻率的关系

以预吸水低活性矿渣替代细集料作为内养护材料,研究低活性矿渣内养护砂浆自收缩与电阻率的变化规律,揭示两者的关系。结果表明：随着低活性矿渣掺量的增加,砂浆早期强度降低幅度大,随着龄期的延长,砂浆中后期强度降低幅度小于早期,建议低活性矿渣的合适掺量取为细集料质量的15%~25%;低活性矿渣内养护对砂浆电阻率发展影响明显,凝结硬化前,浆体电阻率随低活性矿渣掺量的增大而增大;凝结硬化后,浆体电阻率随低活性矿渣掺量的增大而减小;低活性矿渣内养护能有效抑制浆体各阶段的自收缩,尤其在快速收缩阶段和短暂膨胀阶段作用最为明显,同时,36 h龄期后电阻率与自收缩有很好的对应关系,可通过电阻率发展趋势预测自收缩的变化情况。     

工业铜渣作水泥辅料的初步探索

通过铜渣与铁粉分别作水泥辅助原料生产硅酸盐水泥的价格、安定性、凝结时间、强度等性能对比分析 ,论述了工业铜渣生产水泥的可行性。