Low-heat expansive cement (LHEC) is an environmentally friendly and low-carbon cementitious material. Compared to ordinary Portland cement (OPC), LHEC reduces CO2 emissions from the cement production process; furthermore, it enhances the service life of the cement by overcoming the problem of OPC’s strength inversion in hot and humid environments. In order to improve the performance of LHEC in a hygrothermal environment, the strength and expansion of LHEC with different gypsum dosages (8–20%) at curing temperatures of 20 °C, 50 °C, and 80 °C were investigated. The corresponding mechanism was investigated using XRD, TGA, SEM, and porosity analyses. The results indicate that there is a ‘critical gypsum dosage’ for strength at 20 °C. The ‘critical dosage’ rises with the curing temperature or an increase in age. Raising the curing temperature has a better effect on the strength of cement with a higher gypsum dosage; it does not have such a positive effect on cement with a low gypsum dosage. The higher the gypsum content, the greater the expansion rate, and the longer the time needed for the expansion to stabilize. The higher the curing temperature, the shorter the time required for stable expansion and the lower the final expansion rate. Increasing the gypsum dosage and maintaining the temperature promote the hydration of slag and the formation of ettringite (AFt), thereby enhancing the microstructure of the cement. AFt decomposition occurs in the case of a low gypsum dosage and high curing temperature. According to the above results, it is inferred that the strength and expansion performance of LHEC in a hygrothermal environment can be improved by appropriately increasing its gypsum dosage. This finding offers valuable insights for the improvement of LHEC and its application in hygrothermal conditions.

As an environmentally friendly cement material in green buildings, due to its low contribution to air pollution and its substantial use of solid waste, supersulfated cement (SSC) has been extensively studied. However, the low early strength of sustainably utilized SSC needs to be addressed. In order to use SSC to achieve great reductions in energy consumption during industrial production, the effects of triethanolamine (TEA), diethanolisopropanolamine (DEIPA) and triisopropanolamine (TIPA) (with dosages ranging from 0.02% to 0.08%) on the strength and hydration of SSC were studied, and the underlying mechanism was analyzed by TGA, XRD and SEM. The results show that TEA and DEIPA significantly improve the 3-day and 28-day strength of SSC. The former is better at low dosages, while the latter is more suitable for high dosages. TIPA also enhances the 3-day strength of SSC, but it is not as good as the other two alkanolamines. The chelation of alkanolamine with Al3+ ions plays an important role in the strength development of SSC, which accelerates the decomposition of slag and the formation of ettringite. In summary, adding alkanolamines to low-carbon cement systems with a high proportion of industrial by-products such as SSC is a potential and effective solution. In addition, alkanolamines can be used as a strength promoter for most low-carbon blends, which fully utilize solid waste.

This study aims to report the early strength effect and hydration mechanisms of limestone-calcined clay cement (LC3) with sodium carbonate, sodium sulfate and sodium chloride. The experimental results show that it is feasible to add three kinds of insoluble inorganic salts to improve the early strength of LC3 through different promotion methods. In comparison to sodium sulfate, the strengthening effects of sodium carbonate and sodium chloride on early strength of LC3 are more significant. The hydration heat evolution, mercury intrusion porosity and a set of tests for microstructural characterization (XRD, FTIR and SEM) were utilized to better understand the enhancement mechanism of inorganic salts in LC3 system. The mechanism by which sodium carbonate promotes the early strength of LC3 is mainly the strengthening of the aluminate reaction and pozzolanic reaction of metakaolin. The mechanism by which sodium sulfate promotes the early strength of LC3 is mainly the additional ettringite. The mechanism by which sodium chloride promotes the early strength of LC3 is mainly the strengthening of the silicate reaction and the generation of Friedel's salt by alumina from tricalcium aluminate and metakaolin.

采用溶胶-凝胶法制备了Fe掺杂ZnO/TiO2纳米催化剂粉体,利用多种技术手段对样品的组成、形貌、表面化学态、光学性能等进行表征分析,同时通过降解甲基橙溶液来评价样品的光催化性能.研究结果表明,掺杂Fe能稳定ZnO/TiO2的锐钛矿相,细化催化剂颗粒,并且促进光的吸收带隙红移.Fe-ZnO/TiO2的光催化活性相比TiO2显著增强,当Fe掺杂量为1.5％时,光催化活性较为理想.光催化性能的提升可归结为Fe抑制因Zn取代Ti引起的锐钛矿相变,Fe作为电子捕获中心延长光生电子-空穴寿命,以及Fe掺杂引起ZnO/TiO2能带结构改变.

超硫酸盐水泥是一种资源节约和环境友好型胶凝材料,但由于存在早期强度低等缺陷,限制了其推广应用.为提高超硫酸盐水泥早期强度,研究了乳酸钠掺量对超硫酸盐水泥强度的影响,通过ICP-OES、MIP、XRD、SEM等测试,分析了离子浓度、水化产物及微结构,并对相关机制进行了探讨.结果表明,超硫酸盐水泥中掺入少量乳酸钠能提高水泥强度,尤其是早期强度,但是掺量过高时其作用效果降低,甚至对强度不利.综合考虑早期强度和后期强度提高效果,乳酸钠掺量以0.25％(质量分数)左右为宜.乳酸钠提高超硫酸盐水泥强度的主要原因在于其能促进矿渣溶解,加快钙矾石和C-S-H等水化产物生成,从而改善水泥石微结构.

Due to the toxicity and mobility of chromium, the disposal of chromium-containing waste is a pressing issue. Co-processing of chromium-containing waste in a cement kiln is currently one of the most effective methods. However, the presence of water-soluble hexavalent chromium (Cr(VI)) in cement limits the use of this method. In this study, Na2CO3 was used to simulate alkali in industrial raw materials to investigate the pattern of influence of alkali content on water-soluble hexavalent chromium. The mechanisms associated with the oxidation and dissolution of chromium were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma emission spectrometry (ICP-OES). The proportion of Cr(VI) in the clinker detected by XPS increased rapidly with increasing alkali content. In the cement slurry system, alkali promotes more hexavalent chromium leaching by influencing pH and other ion concentrations (Ca2+, SO42−). Therefore, the addition of alkali to either the raw meal or to the cement slurry system will favour an increase in the water-soluble Cr(VI) content. This study may provide theoretical guidance for the preparation and use of clinkers containing chromium.

目前将凹凸棒土作为矿物掺合料替代部分水泥的研究比较缺乏.本文将煅烧凹凸棒土掺入水泥砂浆中,研究煅烧凹凸棒土对水泥砂浆力学及抗氯离子渗透性能的影响.力学性能试验结果表明,煅烧凹凸棒土掺入砂浆能够提高砂浆的抗压强度、抗折强度和劈裂抗拉强度,当掺量为7.5 wt％时,力学性能提高效果最为显著.通过电通量法、快速氯离子迁移系数法评价煅烧凹凸棒土水泥砂浆的抗氯离子渗透性能试验表明,煅烧凹凸棒土掺入砂浆能够降低砂浆的非稳态氯离子迁移系数,提高抗氯离子渗透性能,且7.5wt％为最佳掺量,NTB 492法和RCM法的评价拟合程度确定系数R2为0.9871,说明两者相关度较高.孔结构分析表明,掺入煅烧凹凸棒土可以降低砂浆孔隙率,提高孔结构分形维数,增加孔结构复杂度.由于煅烧凹凸棒土具有较高的火山灰活性,能够促进二次水化、改善孔结构,提高密实度,从而提高水泥砂浆的力学及抗氯离子渗透性能.

针对软锰矿还原煅烧工艺产生的电解锰渣,为探明其对水泥水溶性Cr(Ⅵ)的消解作用,以不同比例的锰渣取代粉煤灰配制水泥,在通风条件和20～120 ℃温度范围贮存1h至28 d,测定各水泥的水溶性Cr(Ⅵ)含量,另外,还测定了常温下各水泥的物理性能和重金属浸出毒性.结果 表明:随着电解锰渣掺量增加,水泥中水溶性Cr(Ⅵ)含量明显下降;贮存温度升高和时间延长,Cr(Ⅵ)含量有一定的反弹,但降铬效果依然十分明显;电解锰渣对水泥物理性能影响不大;水泥重金属浸出浓度均低于GB 3838-2002中Ⅴ类地表水限值.以电解锰渣作水泥降铬材料有可行性,值得进一步研究.

研究了电解锰渣取代石英粉或矿渣微粉对活性粉末混凝土(RPC)强度、收缩率和重金属浸出毒性的影响.结果表明:电解锰渣部分取代石英粉或矿渣微粉,RPC的抗压强度总体上有所提高,而抗折强度稍有下降;干缩率与湿胀率均降低;重金属浸出浓度均低于Ⅴ类地表水限值.

通过无侧限抗压强度和铬浸出毒性试验,研究了碱激发粉煤灰胶凝材料与FeCl2对铬污染土壤(CCS)的固化/稳定化效果.结果表明:随碱激发粉煤灰掺量增加,CCS固化体强度提高,Cr6+和总Cr浸出浓度则下降,但仍保留较高的浓度;FeCl2显著降低CCS的Cr6+和总Cr浸出浓度.碱激发粉煤灰胶凝材料和FeCl2复合固化/稳定化CCS,可使CCS同时具有较高的强度和较低铬浸出浓度,28 d无侧限抗压强度近10 MPa,Cr6+和总Cr浸出浓度低至0.5、1.0 mg/L以下,是一种潜在的资源化利用CCS的方法.

超硫酸盐水泥是一种环境友好的材料,具有水化热低、抗蚀性能好、后期强度高等诸多优点,但存在早期强度低等缺陷.本文综述了超硫酸盐水泥早期强度影响因素及提高途径的研究进展,并对今后的研究方向进行了展望.矿渣活性、硫酸盐浓度,尤其是碱度,是影响该水泥早期强度的关键因素.通过选用活性较高的矿渣和溶解特性合适的石膏,使用具有控制碱度和促进矿渣溶解作用的添加剂等途径,可以有效提高该水泥早期强度.如何控制合适的碱度,进而控制水化产物的形成速率、形态和比例,是值得以后侧重研究的方向.

A new calcium-modified and starch-stabilized ferromanganese binary oxide (Ca-SFMBO)sorbent was fabricated with different Ca concentrations for the adsorption of arsenic (As)and cadmium (Cd) in water.The maximum As(Ⅲ) and Cd(Ⅱ) adsorption capacities of 1％ CaSFMBO were 156.25 mg/g and 107.53 mg/g respectively in single-adsorption systems.The adsorption of As and Cd by the Ca-SFMBO sorbent was pH-dependent at values from 1 to 7,with an optimal adsorption pH of 6.In the dual-adsorbate system,the presence of Cd(Ⅱ) at low concentrations enhanced As(Ⅲ) adsorption by 33.3％,while the adsorption of As(Ⅲ) was inhibited with the increase of Cd(Ⅱ) concentration.Moreover,the addition of As(Ⅲ) increased the adsorption capacity for Cd(Ⅱ) up to two-fold.Through analysis by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR),it was inferred that the mechanism for the co-adsorption of Cd(Ⅱ) and As(Ⅲ) included both competitive and synergistic effects,which resulted from the formation of ternary complexes.The results indicate that the Ca-SFMBO material developed here could be used for the simultaneous removal of As(Ⅲ) and Cd(Ⅱ) from contaminated water.

Chromium (Cr)-bearing electroplating sludge is a hazardous solid waste and has a detrimental effect on human health and the environment. In this study, an alkali-activated slag binders, namely, formed by the reaction of blast furnace slag (BFS) with alkali, was applied to the stabilization/solidification (S/S) of electroplating sludge. The effects of liquid-solid ratio, water glass modulus ratio (molar ratio of SiO2 to Na2O), water glass dosage, and electroplating sludge amount on the compressive strength and Cr leachability of binders were analyzed. The related mechanism of the S/S of electroplating sludge was discussed on the basis of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy coupled with energy-dispersive spectrometry (SEM-EDS). Results showed that the compressive strength of the alkali-activated slag binder first increased and then remained stable with the increase in liquid-solid ratio, water glass modulus ratio, and water glass dosage. By contrast, the leaching concentrations of Cr(VI) and total Cr decreased with the increase in liquid-solid ratio, water glass modulus ratio, water glass dosage, and curing time. In addition, XRD, FTIR, and SEM-EDS revealed that the hydration products of the binders were mainly low-crystallinity and dense calcium silicate hydrate gels, and Cr(VI) had been effectively immobilized in the structure. The reduction in Cr(VI) by the reductive components in the BFS boosted the stabilization of Cr-bearing electroplating sludge. Overall, the BFS binders containing electroplating sludge had relatively high compressive strengths and low Cr(VI) leaching concentrations. The physical encapsulation, chemical bonding, and absorption contributed the Cr immobilization during the S/S process of electroplating sludge.

A new starch stabilized ferromanganese binary oxide (starch-FMBO) with an Fe/Mn ratio of 1.00-2.00 and a synthetic pH of 2 was prepared using an organic polymer (starch) as the stabilizing dispersant. The maximum arsenic adsorption capacity of starch-FMBO was 161.29 mg/g. Adsorption optimization was also conducted, which revealed that starch-FMBO had a high adsorption capacity over a wide pH range (pH 3.0 to pH 11.0) and in the presence of some common anions (HCO3-, SO42-, Cl-, and NO3-). Arsenic removal by FMBO and starch-FMBO followed pseudo-second-order dynamics (R2 ≥ 0.99), indicating that the adsorption rate depended on the chemical adsorption process. Through the analysis of X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR), it was shown that hydroxyl was continuously produced and complexated with As(III) and As(V) during the adsorption process. Thus, the reaction of iron oxide and manganese oxide with arsenic was inferred and explained. The developed starch-FMBO shows promise for its application in the treatment of arsenic-contaminated water.

为探索含铬电镀污泥处置和利用的新技术,以粉煤灰基地质聚合物对含铬电镀污泥进行固化,研究了液固比、水玻璃模数、水玻璃用量、污泥添加量和养护时间对固化体的强度和六价铬浸出浓度的影响,并结合XRD和SEM分析,对固化机制进行了探讨.结果表明,选择适当的液固比、水玻璃用量等参数,污泥添加量高达18％时,地质聚合物90 d抗压强度仍在10 MPa以上,Cr(Ⅵ)浸出浓度低于0.1 mg/L.粉煤灰基地质聚合物对污泥中铬的固化作用可归因于其硬化过程中形成的水化硅铝酸钠凝胶及沸石对铬离子的固溶和吸附.

为探索含铬废弃物在陶粒生产中资源化利用的可行性,在实验室制备掺CrO3的陶粒样品,测定其强度、密度等物理性能和铬浸出浓度,研究Na2 CO3、煅烧制度对铬浸出浓度的影响,并结合XRD和SEM分析探讨铬在陶粒中的固化机制.结果表明:CrO3掺量增加(0％ ～3.0％),陶粒的强度、密度和吸水率变化不大,六价铬和总铬浸出浓度增加,但总体较低,均在0.1 mg/L以下;提高Na2 CO3掺量、提高煅烧温度或冷却速度,六价铬和总铬浸出浓度明显下降.玻璃相对铬的固化起关键作用,玻璃相使陶粒结构致密,包裹铬离子,从而降低铬浸出浓度.陶粒对铬的固化效果良好,含铬废弃物在陶粒生产中的资源化利用具有潜在可行性.

介绍了聚烯烃塑料光降解机理及其影响因素、聚烯烃光降解剂和光降解的可调控性,并对聚烯烃光降解的发展趋势进行了展望.聚烯烃塑料的光降解性能与其化学成分、官能团,添加剂及应力等环境条件有关.光降解剂的选择、光降解剂与稳定剂的匹配,是实现聚烯烃塑料降解可调控性的重要技术途径.开发专用光降解剂及相关复合产品,提高聚烯烃塑料光降解率与可调控性,改善环保性且降低成本是该研究领域的主要方向.

The PONKCS method(based on Rietveld method)was used to determine the periclase content in the ordinary Port-land cement. At the same time,the quantitative method is used for standard samples recovery. The results showed that,the PONKCS method could determine the content of periclase immediately with high accuracy. And the recycling rate could be con-trolled among(100±5)%.

为了优化污泥制备陶粒的工艺,从不同成球工艺、干燥方式、热处理制度、煅烧温度等方面分析了陶粒表面裂缝和孔隙率的变化,并评价所制备陶粒的性能.结果表明,采用自然晾干2h后干燥,接着在400℃预热10 min后在1100℃煅烧30 min是较好的制备工艺,可有效消除陶粒表面裂缝,提高了孔隙率,且陶粒的1h吸水率、抗压强度、软化系数、粒型系数等均符合GB/T17431.1-2010的要求,重金属溶出率符合GB 25467-2010的要求.