矿渣在不同胶凝体系中的水化特性

矿渣具有潜在活性,可用于制备不同类型的水泥.介绍了矿渣的形成与材料特性,在此基础上,将其用于矿渣硅酸盐水泥、超硫酸盐水泥及碱激发矿渣水泥,并分析其在不同胶凝体系中的水化特性.在三种胶凝体系中,矿渣在碱和硫酸盐激发下,形成大量水化硅酸钙和钙矾石等水化产物;随着水化反应的不断发展,使得硬化浆体更加致密,进而提高水泥的强度.     

碱激发矿渣胶凝材料的试验研究

影响碱激发矿渣胶凝材料性能的因素有很多,该文系统地探讨了水玻璃模数、水玻璃掺量、水灰比、养护条件及复合粉料比例等因素对碱激发矿渣胶凝材料凝结时间和强度的影响规律.结果表明:碱胶凝材料凝结时间主要取决于溶液中碱离子浓度;水玻璃模数为1.4,掺量为8％时,碱胶凝材料强度最高;提高养护温度有助于抗压强度的增长,普通硅酸盐水泥与水玻璃配合,可作为复合激发剂使用.     

赤泥-碱矿渣水泥及其制品的研究

本文研究了不同碱激发剂对碱矿渣水泥强度的影响,确定了以硅酸钠和石膏作为复合激发剂,且掺量分别为3%和5%时碱矿渣水泥的强度最高,并分析了激发剂的作用机理。同时研究了赤泥对碱矿渣水泥强度的影响,并研究了利用赤泥-碱矿渣水泥作为基本胶凝材料制造的免烧砖和轻质墙体材料的性能。     

粉煤灰对不同胶凝体系干缩影响

采用干燥收缩试验法研究了粉煤灰对再生微粉和水泥复合胶凝体系、碱矿渣胶凝体系收缩性能的影响。试验结果表明:粉煤灰能明显降低再生微粉和水泥复合胶凝体系、碱矿渣胶凝体系干燥收缩性能;分析了粉煤灰降低不同胶凝体系收缩的机理。     

石灰对矿渣胶凝材料强度的影响

以矿渣的碱激发和硫酸盐激发为理论依据,研究了石灰及石灰复合激发剂对矿渣胶凝材料强度的影响,并讨论了矿渣胶凝材料强度形成的机理.实验结果表明无论是生石灰或消石灰单独激发,还是消石灰和烧石膏、消石灰和烧石膏熟料复合激发,均可获得较高的抗折强度;单独用石灰或消石灰激发,抗压强度仅达到普通22.5水泥(P·O22.5)标准,用消石灰、熟料和烧石膏复合激发可获得较高的抗压强度.     

金川矿山矿渣-粉煤灰基早强充填胶凝材料试验

利用唐钢矿渣和粉煤灰火山灰质材料,以生石灰、芒硝和亚硫酸钠作为复合激发剂,开展满足金川镍矿下向分层进路胶结充填要求的矿渣-粉煤灰基胶凝材料研究。对比分析唐钢和酒钢矿渣的化学成分和质量评价结果发现,唐钢矿渣质量优于酒钢;河砂粗骨料级配分析结果表明,该骨料较粗,级配不良。利用酒钢矿渣替代唐钢矿渣进行矿渣-粉煤灰基胶凝材料试验,结果表明:利用酒钢矿渣开发的金川矿山充填胶凝材料的胶结充填体强度低于唐钢矿渣开发的充填胶凝材料,不能满足金川矿山要求。为此,进一步开展酒钢矿渣-粉煤灰基充填胶凝材料早强剂和水泥复配激发剂胶结充填体强度试验研究,基于3水平4因素正交试验和极差分析,得到影响充填体早期强度的激发剂因素排序为:脱硫灰渣生石灰粉煤灰水泥。最后通过建立神经网络预测模型,预测5水平正交试验充填体强度和激发剂配方优化方案,并进行验证试验。研究结果表明,激发剂最优配方为:生石灰5%、脱硫灰渣5%、粉煤灰15%和水泥15%,由此制备的胶凝材料能够满足金川矿山充填强度要求。     

碱-矿渣-粉煤灰水泥 第Ⅰ部份 配合比试验设计和影响强度的诸因素

矿渣和粉煤灰均为工业废渣,粒化高炉矿渣具有潜在水硬性,粉煤灰则能起火山灰反应,本文研究的目的在于利用碱激发矿渣的潜在水硬性,使矿渣水化物与粉煤灰进行火山灰反应,在矿渣与粉煤灰适宜配合比的基础上,制得一种不经煅烧的节能、省资源新型胶凝材料。文中采用混料回归设计中单形格子法确定配料试验方案。以水泥强度作为响应函数,得出回归方程式,并用微机处理数据,绘出强度等值线,从中找出碱-矿渣-粉煤灰水泥的最优配比。此外,除碱-矿渣-粉煤灰系统的配合比对水泥强度有影响,碱性激发剂的种类,矿渣质量和粉磨细度,外加剂的掺加等工艺因素对强度也有影响,对此亦进行了探讨。     

复合活化剂对高掺量矿渣胶凝材料性能及其作用机理的影响

针对水泥-高掺量矿渣胶凝材料早期强度发展缓慢的现象,自行设计开发了一种用于激发矿渣早期水化活性的复合活化剂,对比研究了复合活化剂与纯硫酸盐对水泥-矿渣胶凝材料性能以及水化机理的影响。结果表明:复合活化剂与纯硫酸盐均能在水化1 d内提高水泥熟料和矿渣的反应程度,促进矿渣产物形态提前由外部水化产物向内部水化产物过渡,提升胶凝材料早期宏观性能;然而使用纯硫酸盐激发的胶凝材料后期性能下降,可能是由于生成过量钙矾石所造成;复合活化剂则通过促进水泥熟料水化、加速矿渣溶解、反应以及改善微观结构性能等提高胶凝材料早期强度提升,对后期性能无副作用。     

电石渣激发磷渣-矿渣-水泥复合胶凝材料的性能研究

矿渣作为一种工业固废因其优异的火山灰活性得到了广泛的应用,而磷渣作为黄磷工业的固废由于磷的缓凝作用,其利用率依旧较低.以矿渣与磷渣为主要胶凝材料,电石渣为碱激发材料,展开磷渣-矿渣-水泥三元体系胶凝材料的性能研究.结果表明:电石渣的激发效果随磷渣/矿渣质量比的增大而愈加显著;随磷渣/矿渣比例降低,激发体系的早期强度呈增大趋势,而后期强度呈减小趋势;磷渣与矿渣质量比为60:30时,电石渣激发后材料体系可兼顾早期与后期力学性能.     

高炉矿渣微粉的火山灰活性评价与影响因素

高炉矿渣微粉作为一种常用的辅助胶凝材料,由于其较强的潜在胶凝活性被广泛应用于水泥混凝土中。因此,矿渣微粉的火山灰活性发挥对水泥混凝土材料的力学性能与耐久性尤其重要。文中以马钢矿渣微粉为例对其火山灰活性进行了综合评价,并根据国内外研究进展归纳总结了影响其火山灰活性的关键因素,为矿渣微粉的改性与在水泥混凝土中应用提供参考。     

Intrinsic differences in atomic ordering of calcium (alumino)silicate hydrates in conventional and alkali-activated cements

The atomic structures of calcium silicate hydrate (C–S–H) and calcium (–sodium) aluminosilicate hydrate (C–(N)–A–S–H) gels, and their presence in conventional and blended cement systems, have been the topic of significant debate over recent decades. Previous investigations have revealed that synthetic C–S–H gel is nanocrystalline and due to the chemical similarities between ordinary Portland cement (OPC)-based systems and low-CO₂ alkali-activated slags, researchers have inferred that the atomic ordering in alkali-activated slag is the same as in OPC–slag cements. Here, X-ray total scattering is used to determine the local bonding environment and nanostructure of C(–A)–S–H gels present in hydrated tricalcium silicate (C₃S), blended C₃S–slag and alkali-activated slag, revealing the large intrinsic differences in the extent of nanoscale ordering between C–S–H derived from C₃S and alkali-activated slag systems, which may have a significant influence on thermodynamic stability, and material properties at higher length scales, including long term durability of alkali-activated cements.     

Performance of volcanic ash and pumice based blended cement concrete in mixed sulfate environment

The deterioration of concrete structures due to the presence of mixed sulfate in soils, groundwater and marine environments is a well-known phenomenon. The use of blended cements incorporating supplementary cementing materials and cements with low C₃A content is becoming common in such aggressive environments. This paper presents the results of an investigation on the performance of 12 volcanic ash (VA) and finely ground volcanic pumice (VP) based ASTM Type I and Type V (low C₃A) blended cement concrete mixtures with varying immersion period of up to 48 months in environments characterized by the presence of mixed magnesium-sodium sulfates. The concrete mixtures comprise a combination of two Portland cements (Type I and Type V) and four VA/VP based blended cements with two water-to-binder ratio of 0.35 and 0.45. Background experiments (in addition to strength and fresh properties) including X-ray diffraction (XRD), Differential scanning calorimetry (DSC), mercury intrusion porosimetry (MIP) and rapid chloride permeability (RCP) were conducted on all concrete mixtures to determine phase composition, pozzolanic activity, porosity and chloride ion resistance. Deterioration of concrete due to mixed sulfate attack and corrosion of reinforcing steel were evaluated by assessing concrete weight loss and measuring corrosion potentials and polarization resistance at periodic intervals throughout the immersion period of 48 months. Plain (Type I/V) cement concretes, irrespective of their C₃A content performed better in terms of deterioration and corrosion resistance compared to Type I/V VA/VP based blended cement concrete mixtures in mixed sulfate environment.     

Properties of Calcined Clay Waste and its Influence on Blended Cement Behavior

This paper describes research on clay wastes (CWs) produced in the paper manufacture process. Once activated under controlled thermal conditions, CW is transformed into calcined clay products providing added value as supplementary cementing materials. The obtention of a pozzolanic material (metakaolin (MK)) from valorized CW constitutes an alternative source of pozzolans for the elaboration of blended Portland cements, as well as a priority research line from the environmental point of view. This research work presents the properties of calcined CW (chemical, mineralogical, and pozzolanic) and its influence on Portland cements containing 10% calcined clay product. The results obtained with different characterization techniques (XRF, DTA, XRD, SEM-EDX) showed that the thermally activated CW exhibits acceptable properties to be used as supplementary cementing materials in the manufacture of commercial Portland cements. The derived MK can react with calcium hydroxide, from cement hydration, producing hydrated phases with hydraulic properties (calcium silicate hydrate gels, tobermorite, C₄AH₁₃, zeolite). These novel blended cements comply with the chemical, physical, and mechanical specifications established in the existing standards.     

碱-矿渣水泥的水化、力学及干缩性能研究进展

碱-矿渣水泥是一种优良的绿色胶凝材料,由矿渣部分或全部取代水泥而制成。在碱激发剂的作用下矿渣水化产生活性,并且由于其独特的玻璃体分相结构导致碱-矿渣水泥的水化硬化产物表现出不同于普通硅酸盐水泥基材料的性能。本文介绍了矿渣的组成与结构,从理论层面解释碱-矿渣水泥具有潜在活性的原因,探讨了不同激发剂作用下碱-矿渣水泥的水化机理,并在此基础上综述其基本力学性能和干缩特性,为其在工程实践中的应用和推广提供依据。结合相关文献,总结了现有研究的不足并对今后的发展提出了建议。     

Approaches to improve the properties of wood fiber reinforced cementitious composites

In an attempt to improve the workability, stability, and physical and mechanical properties of wood fiber-reinforced cementitious composites (WFRCs), alkali-activated blended cements have been explored for their compatibility with various wood fibers such as hardwood fiber, recycled newspaper fiber and recycled kraft paper fiber. Methods including high shear mixing, modifying the cement matrix with silica fume, and molding pressure were evaluated as means for further strengthening the wood fiber-reinforced cement composites. Flexural strengths up to 40 MPa. along with enhanced toughness have been achieved.     

碱胶凝材料水化产物C-A-S-H与N-A-S-H的研究进展

碱胶凝材料作为一种新型低碳建筑材料,以其优异的性能成为当前研究的热点领域之一.对近几年国内外对碱胶凝材料主要水化产物C-A-S-H与N-A-S-H结构组成特点及人工合成方法等方面的研究进展进行了综述,当前人工合成C-A-S-H与N-A-S-H的主要方法有溶胶-凝胶法、水热法和化学沉淀法等,合成所得的C-A-S-H与N-A-S-H体系产物也与合成方法密切相关.通过总结目前已有的合成方法,对比分析了各种合成方法的优缺点,并提出了当前研究中一些亟待解决的问题和未来研究发展方向.     

A review: The comparison between alkali-activated slag (Si + Ca) and metakaolin (Si + Al) cements

There are two main models of alkali-activated cements, one is the case of the activation of slag (Si + Ca) and the other is activation of metakaolin (Si + Al). This paper reviews current knowledge about the comparison between alkali-activated slag (Si + Ca) and metakaolin (Si + Al) cements, including the general properties of slag and metakaolin, hydration products reaction mechanisms, and the role of Ca and Al.     

碱激发胶凝材料固化Pb2+及浸出毒性的试验研究

本文对碱激发胶凝材料(碱-偏高岭土、碱-矿渣和碱-粉煤灰)与水-水泥体系固化Pb2+进行了试验研究,其中水-水泥体系为对比样.结果表明:与水泥相比,碱激发胶凝材料能显著降低重金属离子(Pb2+)浸出浓度,其规律性与其NH+4交换容量大小的规律性一致,与其固化体的抗压强度的大小没有相关性;水泥固化重金属离子Pb2+在养护28 d后还不断浸出,而碱激发胶凝材料固化重金属离子Pb2+在养护28 d后已稳定.     

外加剂对二灰稳定尾矿料混合料早期强度增长的影响与机理分析

对二灰 (石灰与粉煤灰 )稳定尾矿料混合料在不同外加剂掺量下的早期强度增长规律进行系统研究 ,对其早期强度增长机理进行分析探讨。研究表明 ,二灰稳定尾矿料混合料主要是通过Ca(OH) 2 与粉煤灰中的活性组分反应生成胶凝成分把尾矿料胶结起来形成强度 ,在石灰 -粉煤灰 -尾矿料反应体系中 ,掺入外加剂的主要目的在于激发粉煤灰的早期活性并促进混合料早期强度增长 ,同时外加剂也参与反应生成具有胶凝性的成分 ,并起到胶结作用 ,进一步密实混合料结构     

Improvement of the durability of glass fiber reinforced cement using blended cement matrix

Blended cements prepared with two fly ashes were used as matrices in glass fiber reinforced cement (GRC) composites in an attempt to improve their durability. The hydrated matrices from the two blended cements investigated here had similar strength and composition. Both fly ashes reduced the Ca(OH)₂ content to the same extent but in both cases the pH level was only slightly reduced compared to the portland cement matrix. In spite of these similarities, the GRC prepared with one fly ash showed considerable improvement in durability while the other one had only a small positive effect. SEM observations indicated that the improved durability in one case was associated with modification in the microstructure of the hydration products deposited in between the glass filaments, resulting in a much more open structure compared to that of portland cement matrix or the other blended cement. It is therefore suggested that the potential of the blended cement matrix to improve the durability of GRC is associated with its ability to modify the microstructure of the paste at the glass interface. This characteristic is not necessarily related to the overall composition of the blended cement matrix and to the reactivity of fly ash with Ca(OH)₂.