Basic magnesium sulfate cement (BMSC) is renowned for its superior mechanical properties and durability. However, it's slow early strength development and prolonged setting time limit broader applications. This study systematically investigates the effects of the synthetic 5 & centerdot;1 & centerdot;7 (5Mg(OH)(2)& centerdot;MgSO4 & centerdot;7H(2)O) whiskers on BMSC performance through mechanical properties testing, hydration analysis, and microstructural characterization. Results demonstrate that incorporating the synthetic 5 & centerdot;1 & centerdot;7 whiskers promotes secondary nucleation and growth of the 5 & centerdot;1 & centerdot;7 phase, accelerating hydration and effectively replacing traditional modifiers to shorten setting time by up to 50%. The synthetic 5 & centerdot;1 & centerdot;7 whiskers induce intensive growth of the 5 & centerdot;1 & centerdot;7 phase in the matrix, enhance aspect ratio and boost early compressive strength by 30-40%. Additionally, the synthetic 5 & centerdot;1 & centerdot;7 whiskers reduce MgO residues, improving water resistance with a softening coefficient increment of 15-20%. Thus, the synthetic 5 & centerdot;1 & centerdot;7 whiskers provide an advanced method to enhance the performance of BMSC while effectively replacing traditional modifiers.

Basic magnesium sulfate cement (BMSC) is a kind of magnesium oxide (MgO)–magnesium sulfate (MgSO 4 )–water (H 2 O) modified ternary cementitious material prepared from light burned magnesia, magnesium sulfate heptahydrate, water and additives. The effects of α-magnesium oxide/magnesium sulfate ratio (MO/MS), water/magnesium sulfate ratio (W/MS), sand-to-binder ratio (s/b) and superplasticiser dosage (SPD) on the performance of BMSC mortar were studied for the first time in this work. The results showed that for, optimal 28-day flexural strength, α-MO/MS = 10:1, W/MS = 16:1, s/b = 0.8 and SPD = 0.3%. For optimal 28-day compressive strength, α-MO/MS = 8:1, W/MS = 14:1, s/b = 0.6 and SPD = 0.4%. For best water resistance, α-MO/MS = 12.5:1, W/MS = 14:1, s/b = 0.2 and SPD = 0.1%. Based on these results, the basic mix proportion ranges of BMSC mortar should be α-MO/MS = 8:1–12.5:1, W/MS = 14:1–16:1, s/b = 0.2–0.6 and SPD = 0.1–0.4%.

The application of reactive powder concrete (RPC) was not wide. One of the main problems was that copper-coated steel fibres (CSF) were expensive. In order to prepare low-cost RPC and resource utilisation of waste steel fibres recycled from scrap tires (WSF), this paper investigated the fluidity and strength of RPC containing WSF. The results indicated that the fluidity of RPC containing WSF was worse than that of RPC containing CSF. But there was not much difference in the strength of two kinds of RPC. In order to optimise performance of RPC containing WSF, the influence of mineral admixtures on the fluidity and strength of RPC was discussed. The results indicated that the optimum silica fume dosage was 20%, and the optimum fly ash and limestone powder dosages were 5%, respectively. Through this study, it was completely feasible to prepare RPC containing WSF. The use of WSF can reduce the cost of RPC.

Water-based rock debris is a new solid waste in recent years, which has not been used in cement industry on a large scale. In this paper, the feasibility of water-based rock debris replacing part of the cement raw material is verified by the combination of laboratory test and field test. By laboratory and field tests, it has been proved that it is feasible in industry to replace part of cement raw material with water-based rock debris, which can produce qualified cement clinker and meet national standards of environmental protection.

Magnesium oxysulfate cement has low strength and poor water resistance, so an additive is essential for the preparation of basic magnesium sulfate cement (BMSC). In this paper, the effects and the mechanisms of three organic weak acids on the water resistance in relation to flexural strength of BMSC are investigated. The results show that malic acid fails to ameliorate the water resistance in relation to flexural strength, but citric acid and tartaric acid are successful. The ionisation constant and molecular formulas of different weak organic acids can affect the performance, such as fluidity, strength and water resistance. Therefore, the effect of citric acid is better than tartaric acid, and the optimal dosage of citric acid is 1.0%.

Taking the pretreated copper tailings as the research object,the effects of the treated copper tailings on the calcination process of cement clinker properties and the properties of clinker were studied when the siliceous raw materials were replaced by treated copper tailings with high content or full content(5%,10%,15%and 18.22%).The results show that when the treated copper tailings are high or even completely replace siliceous raw materials,the burnability of raw meal becomes better,and the difficulty of C3S generation is reduced.Before and after the incorporation of copper tailings,the crystal structure of C3S in the clinker did not change,and the crystal form was M3 type.The standard consistency and water consumption,setting time and stability of cement clinker calcined at 1 450℃all meet the specifications in GB/T 21372-2008"Portland cement clinker",and its mechanical properties are significantly improved compared with those without copper tailings.

现有研究表明不同改性剂对碱式硫酸镁水泥(BMSC)中517相的生长有影响.本工作使用六种不同羟基含量的改性剂,借助X射线衍射仪、扫描电子显微镜、拉曼光谱仪和压汞仪研究了改性剂相同质量掺量下BMSC的力学强度、物相组成和微观结构.实验结果表明,添加富羟基的磷酸二氢钠和磷酸二氢钾试样中517相含量最高,长径比最大,抗压强度较对照组提升近一倍,软化系数接近1.00;BMSC中孔隙主要为晶间孔,长径比大的517相使孔径分布更集中、总孔隙率更低.BMSC耐水性能与517相含量、形貌有关,使用富羟基的改性剂能促进517相的结晶生成,从而提高517相含量及其长径比,改善其耐水性能.

随着新型墙体材料的不断更新,急需对不同墙体材料建筑物整体的能耗情况进行探究,利用Ecotect Anlysis软件,建立民用住宅建筑模型,对比几种常见墙体材料的保温隔热性能.结果表明,树脂透光混凝土的保温性能最优,其次分别是加气混凝土空心砌块、多孔硫氧镁混凝土、实心黏土砖,为住宅建筑的节能优化设计提供一定的理论依据.

水基岩屑作为固体废弃物,急切需要找到合理的解决措施.通过对两种水基岩屑的化学成分和矿物相的分析,探索利用水基岩屑制备水泥熟料的可行性.将两种水基岩屑按5％的掺量加入水泥原料,在三个温度点(1350℃、1400℃、1450℃)下煅烧熟料,对熟料的煅烧过程进行X射线衍射分析、易烧性分析及岩相分析,实验结果表明,水基岩屑的成分与水泥原料相近,可以替代部分水泥原料煅烧熟料.水基岩屑的掺入会略微增加fCaO的含量,但影响不大,掺量较高时会影响Alite的生长.

Providing lighting and beautifying night lights of the city cause a large amount of electricity consumption.Using self-luminescent concrete to replace some night lighting projects will reduce the consumption of electricity, enhance the effect of energy conservation and emission reduction, and accelerate the realization of China’s 2060 carbon neutrality target.According to the existing new building luminescent materials and translucent resin concrete preparation process, this article prepares a new type of self-luminescent concrete by using basic magnesium sulfate cement.Using luminescent intensity and afterglow value as evaluation indexes, the optimal luminescence property was explored with the help of Matlab software.The study shows the luminescence properties of self-luminescence concrete reach the best when the ratio of water-sulfur is 1∶15 and the content of water reducer is 0.76%.The increase in the doping amount of luminescent materials is positively correlated with the luminescent intensity, and the doping amount of 13 % is appropriate.The increase of the size of the luminescent rod also has a positive effect, and the size range is better in 9 mm.

磷石膏的化学成分与天然石膏类似,磷石膏通常用作水泥的缓凝剂,通过一定比例与熟料混合制成水泥.向磷石膏中外掺一定量的可溶性氟,研究可溶性氟含量对硅酸盐水泥与外加剂相容性及强度的影响.研究结果表明:在减水剂掺量较少的情况下,随着氟离子掺量的增加,Marsh时间有着明显的增加;随着氟离子的增加,硅酸盐水泥3 d和28 d的抗压、抗折强度变化不明显,与对照组的差异不大.

活性粉末混凝土(RPC)是一种水泥基复合材料,但素RPC存在脆性大的不足.虽然钢纤维对RPC的力学性能改善效果极为显著,但在低水胶比情况下,其流动性较差,使得性能提升受到限制.研究可再分散乳胶粉对含钢纤维RPC物理性能、力学性能及微观结构的影响.研究发现,添加质量分数1％的可再分散乳胶粉,能使含钢纤维RPC获得最佳的流动性、较高的抗折强度和韧性.这种影响是由于可再分散乳胶粉乳化后形成聚合物膜,在水泥基体中贯穿形成三维的网状结构.因此,在可再分散乳胶粉的合适掺量下可进一步改善含钢纤维RPC的抗折强度.

In order to improve the toughness of reactive powder concrete doped steel fibers, a novelty method of multi-scale toughening cement-based materials was investigated. The multi-scale synergistic toughening cement-based materials (nominated basic magnesium sulfate cement based reactive powder concrete, BMSC based RPC) were designed and discussed for the first time by endogenous whiskers and doped steel fibers. Through orthogonal trials, curing regimes, sand packing and optimization of steel fibers dosage, the synergistic toughening at different microscales was realized by using the properties of endogenous whiskers (the 5.1.7 phase) and doped steel fibers. The results showed that the 28-day flexural strength and compressive strength of BMSC based RPC were 21.4 MPa and 120.5 MPa under ambient temperature curing, respectively, when the steel fibers dosage was 2% (volume fraction). The preliminary research proved that the toughness of reactive powder concrete can be further improved under the multi-scale synergistic toughening effect of endogenous whiskers and doped steel fibers.

树脂作为树脂透光混凝土中的导光体,是影响树脂透光混凝土透光性能的主要构件.为了更加全面地研究各参数对导光体透光性能的影响,基于有限元仿真模拟软件COMSOL Multiphysics,对导光体在相互平行的直射光下的透光率变化进行了模拟研究;并且计算了树脂透光混凝土的有效照度分数.结果 表明,水泥砂浆壁面的反射率、光线的入射角以及导光体长度和半径都会影响树脂透光混凝土的透光率.水泥砂浆壁面的反射率越大,入射角越大,导光体长度越长、半径越小,则透光率越大.光线的入射角对导光体的透光率较大;当反射率从0增加到0.6时,导光体透光率的增长不明显,透光率的增加量均＜2％.而当反射率＞0.6后,导光体透光率开始明显增大,并且增长速率也随之增大.太阳入射角对导光体的透光率影响较大,导致了树脂透光混凝土的有效照度分数普遍低于55％.

加快实现我国高等教育治理体系和能力现代化需要关注空间向度.后疫情时代,随着高等教育更深层次地步入网络社会,教育资源、教学活动、教育治理的"流动空间"将进一步拓展.面对新的空间演进,高等教育治理体系的完善和治理能力的提升亟待实现网络化、数字化转型升级.网络化治理作为一种强调系统性并通过"跨界"协同提升公共价值的治理新范式,成为后疫情时代我国应对高等教育"流动空间"拓展的新治理路径.目前,我国高等教育网络化治理在治理体系、治理机制、治理技术等方面存在一定困境,亟须完善高等教育网络化治理体系以促进治理流聚合,完善高等教育网络化治理机制以促进治理流耦合,优化高等教育网络化治理信息化技术平台以促进治理流契合.

碱式硫酸镁水泥是近几年研发出的一种新型水泥,具有高折压比的特点.而目前市面上的减水剂都是针对硅酸盐水泥体系的.因此,针对匹配碱式硫酸镁水泥的减水剂研发,具有支撑该水泥工程化应用的意义.本文采用单因素法和正交实验法研究萘系减水剂的合成配比,并且探究萘系减水剂的pH值、掺量以及硫酸根含量对碱式硫酸镁水泥净浆流动度和经时损失的影响.结果表明:合成配比对萘系减水剂性能的影响程度为酸萘比>醛萘比>水萘比,最优配比为酸萘比1.4、醛萘比0.96、水萘比3.5;水灰比为0.48,掺入4.4％萘系减水剂后流动度高达194 mm;减水剂的pH值对碱式硫酸镁水泥流动度的影响不明显;随着硫酸根含量的增加,体系中析出较多的硫酸镁晶体从而使流动度下降;自制萘系减水剂与市售萘系减水剂相比,流动度的经时损失相对较好.

介绍并分析了下出风逆流式旋风预热器的原理及优势.在改进了旋风预热系统C1的换热方式后,出口烟气温度相较传统预热器有所降低并且低于出口物料温度,熟料煤耗降低,产量提高.

Reactive powder concrete (RPC) has excellent mechanical properties and durability, but its excellent properties are mainly obtained by selecting materials (high cost) and complicated curing process. From the point of view of reducing production cost and optimizing properties, we used waste steel fibers to replace traditional copper-coated steel fibers to prepare reactive powder concrete, and focused on the influence of curing regime on the properties of reactive powder concrete containing waste steel fibers. Through strength test, X-ray diffraction, scanning electron microscopy and mercury intrusion porosimetry analysis, it is concluded that high temperature steam curing makes RPC have higher strength and denser microstructure in comparison with ambient temperature curing, but hot air curing can make hydration products appear crystallization and increase porosity. High temperature steam curing at 80-90 degrees C for 2-3 days is proper. Appropriate pre-curing can further increase the strength of RPC, and the optimum curing regime for better compressive strength is water pre-curing for 2 days and then high temperature steam curing at 80 degrees C for 2 days. (C) 2019 Elsevier Ltd. All rights reserved.

Circulating fluidized bed combustion ash (CFBC ash) is the waste of coal-fired circulating fluidized bed power plant boiler. CFBC ash contains amounts of free lime and anhydrite, which has a self-hardening and expansion property. This paper studies the influence of CFBC ash fineness and lime or slaked lime dosage on the physical properties, strength and phase evolution of binary cementitious materials (lime or slaked lime-CFBC ash). The experimental results show that when lime or slaked lime dosage is below 30%, through CFBC ash getting finer, setting time of binary cementitious materials becomes shorter and compressive strength of that increases, but water requirement of normal consistency of that decreases to some extent. And when CFBC ash fineness is constant, with the increment of lime dosage, setting time of binary cementitious materials becomes shorter and water requirement of normal consistency of that increases, but compressive strength of that declines first and then increases. But when CFBC ash fineness is constant, with the increment of slaked lime dosage, setting time of binary cementitious materials becomes longer and compressive strength of that declines, but water requirement of normal consistency of that increases. (C) 2020 Elsevier Ltd. All rights reserved.