Utilization of Thermally Treated Flue Gas Desulfurization (FGD) Gypsum and Class-C Fly Ash (CFA) to Prepare CFA-Based Geopolymer

The feasibility of utilization of flue gas desulfurization （FGD） gypsum and Class-C fly ash （CFA） to prepare CFA-based geopolymer were studied. The results showed that geopolymer made from 90% CFA and 10% FGD gypsum （FGDG） which was thermally treated at 800 ℃ for 1 h obtained the better compressive strength of 37.0 MPa. The micro characteristics and structures of the geopolymer samples of CFA and CFA-FGDG were tested by XRD, FT-IR, and SEM-EDXA after these samples cured at 75 ℃ for 8 h followed by 23 ℃ for 28 d. Both the geopolymer samples of CFA and CFA-FGDG have significant asymmetric stretching of A1-O/Si-O bonds and Si-O-Si / Si-O-A1 bending band. In geopolymer sample of CFA-FGDG, a small quantity of lathy products probably being the ettringite wrapped over the spherical fly ash particle, and the concentration of sulfur is much more than that in geopolymer sample of CFA. It is indicated that FGD gypsum may react during alkali-activated and geopolymeric process.

Effects of Steel Slag Powder on Workability and Durability of Concrete

The workability and durability of a type of sustainable concrete made with steel slag powder were investigated. The hydrated products of cement paste with ground granulated blast furnace slag（GGBFS） alone or with a combined admixture of GGBFS-steel slag powder were investigated by X-ray diffraction（XRD）. Furthermore, the mechanism of chemically activated steel slag powder was also studied. The experimental results showed that when steel slag powder was added to concrete, the slumps through the same time were lower. The initial and fi nal setting times were slightly retarded. The dry shrinkages were lower, and the abrasion resistance was better. The chemically activated steel slag powder could improve compressive strengths, resistance to chloride permeation and water permeation, as well as carbonization resistance. XRD patterns indicated that the activators enhanced the formation of calcium silicate hydrate（C-S-H） gel and ettringite（AFt）. This research contributes to sustainable disposal of wastes and has the potential to provide several important environmental benefi ts.

Conductive Mortar as Anode Material for Cathodic Protection of Steel in Concrete

The behavior of a new type of secondary anode material made of carbon fiber reinforced cement used for cathodic protection of steel in concrete was studied. The mechanical, electrical and electrochemical properties of this conductive mortar were investigated. Results indicate that the addition of carbon fiber enhances the strength and ductility of the mortar, as well as the electrical property. The anodic polarization behavior was tested on specimens immersed in aqueous solutions of saturated Ca（OH）2 in the presence or absence of 3% NaCl. Based on impedance measurements the electrochemical parameters of conductive mortar were calculated. It is shown that the investigated conductive mortar can be used in cathodic protection of reinforced concrete. The study also shows that the optimum fiber content in mortar should be in the range from 0.5 vol% to 0.7 vol%.

生物荧光染料罗丹明表征水泥基材料内部相对湿度的研究

水泥基材料内部水分的传输与分布对材料性能和耐久性有重要意义。传统的宏观土木工程监测湿度设备并不能原位捕捉水泥基材料内部微细观尺度的湿度情况。本文提出一种利用罗丹明6G荧光表征不饱和水泥基材料内部相对湿度变化的方法,设计了预先拌入式和成型后涂抹式两种成型工艺,探索了最佳配制浓度。试验结果表明:罗丹明6G可以通过荧光强度原位反映水泥基材料薄层的相对湿度,对水泥基材料水化放热和水化产物的几乎没有影响;荧光强度在内部相对湿度为63%~75%时较高。研究结果为生物荧光材料在建筑外墙容易因湿度累积导致空鼓脱落、结构混凝土表层易开裂损伤区域的监测、检测提供了基础研究。

Rietveld quantification of γ-C_2S conversion rate supported by synchrotron X-ray diffraction images

The pure γ-Ca2SiO4(γ-C2S) phase was prepared at 1623 K of calcining temperature, 10 h of holding time and furnace cooling. The β-C2S phase was obtained through γ-C2S conversion with the following calcination system which was adopted at1473 K of calcining temperature, 1 h of holding time and then water-cooling. The conversion rate of γ-C2S was studied by the Rietveld quantitative laboratory X-ray powder diffraction supported by synchrotron X-ray diffraction images. The refinement results show that the final conversion rate of γ-C2S is higher than 92%. The absolute error of the γ-C2S conversion rate between two Rietveld refinements(sample with or without α-Al2O3) is 3.6%, which shows that the Rietveld quantitative X-ray diffraction analysis is an appropriate and accurate method to quantify the γ-C2S conversion rate.

Effect of temperature on the hydration process and strength development in blends of Portland cement and activated coal gangue or fly ash

This paper describes the results of an investigation into the effect of the variation of curing temperatures between 0 and 60 °C on the hydration process,pore structure variation,and compressive strength development of activated coal gangue-cement blend(ACGC) . Hardened ACGC pastes cured for hydration periods from 1 to 360 d were examined using the non-evaporable water method,thermal analysis,mercury intrusion porosimetry,and mechanical testing. To evaluate the specific effect of activated coal gangue(ACG) as a supplementary cementing material(SCM) ,a fly ash-cement blend(FAC) was used as a control. Results show that raising the curing temperature accelerates pozzolanic reactions involving the SCMs,increasing the degree of hydration of the cement blends,and hence increasing the rate of improvement in strength. The effect of curing temperature on FAC is greater than that on ACGC. The pore structure of the hardened cement paste is improved by increasing the curing temperature up to 40 °C,but when the curing temperature reaches 60 °C,the changing nature of the pore structure leads to a decrease in strength. The correlation between compressive strength and the degree of hydration and porosity is linear in nature.

Significantly enhanced thermoelectric performance of flexible PEDOT nanowire film via coating Te nanostructures

A free-standing and highly conductive poly(3,4-ethylenedioxythiophene)(PEDOT)nanowire(NW)film was used as a working electrode for electrodepositing tellurium(Te).By adjusting the electrodeposition time,the thermoelectric(TE)performance of the free-standing hybrid filmwas optimized.The maximum power factor of 240.0 μWm^(-1) K^(-2)(with the electrical conductivity of 561.4 S cm^(-1) and the Seebeck coefficient of 65.4 μVK^(-1))was obtained from a hybrid film electrodeposited for 7 h,which was 8 times higher than that of the pristine PEDOT NW film.In addition,the electrical conductivity of the film almost did not change even after being bent for 400 times around a rod with radius of 4 mm,indicating an excellent flexibility.This work offers a facile approach to prepare multilayered TE films,and desirable combination of excellent flexibility,high electrical conductivity,and facile process scalability makes the free-standing PEDOT NW film particularly promising for portable and flexible electronics.

Deciphering the Role of Fluoroethylene Carbonate towards Highly Reversible Sodium Metal Anodes

Sodium metal anodes(SMAs)sufer from extremely low reversibility(<20%)in carbonate based clectrolytes-this piece of knowledge gained from previous studics has ruled out the application of carbonate solvents for sodium metal batteries.Here,we overturn this conclusion by incorporating fluoroethylene carbonate(FEC)as cosolvent that renders a Na plating/stripping fficiency of>95%with conventional NaPF。salt at a regular concentration(1.0M).The peculiar role of FEC is firstly.unraveled via its involvement into the solvation structure,where a threshold FEC concentration with a coordination number>1.2 is needed in guaranteeing high Na reversibility over the long-term.Specifially,by incorporating an average number of 1.2 FEC molecules into the primary Na*solvation sheath,lowest unoccupied molecular orbital(LUMO)levels of such Nat-FEC solvates undergo further decrease,with spin electrons residing either on the O=C 0(O)moiety of FEC or sharing between Na*and its C=:O bond,which ensures a prior FEC decomposition in passivating the Na surface against other carbonate molecules.Further,by adopting cryogenic tranmission electron microscopy(cryo-TEM),we found that the Na filaments grow into substantially larger diameter from-400nm to>1 pum with addition of FEC upon the threshold value.A.highly crstalline and much thiner(-40 nm)slid-electrolyte interphase(SED)is consequently observed to uniformly wrap the Na surface,in contrast to the severely corroded Na as retrieved from the blank electrolyte.The potence of FEC is further demonstrated in a series of"corrosive solvents"such as ethy!l acetate(EA)。trimethyl phosphate(TMP),and actonitrile(AN)enabling highly reversible SMAs in the otherwise unusable solvent systems.

Performance development of styrene-butadiene copolymer-modified calcium sulfoaluminate cement mortar under different curing conditions

The purpose of this study was to investigate the change in the physical and mechanical properties of styrene-butadiene copolymer(SB)dispersion-modified calcium sulfoaluminate(CSA)cement mortar as it aged from 28 to 360 d,and cured at different temperatures and relative humidities.The results show that the mechanical properties of reference mortar(RM)of CSA cement,including its flexural,compressive,and tensile bond strength,showed a reduction after a certain time,but its water capillary absorption was hardly affected by age.When SB dispersion was added,there was no reduction in mechanical strength.The amount of SB added did matter.Addition of 5% SB had a negative effect on most properties compared with RM,except for tensile bond strength.However,the properties of SB-modified mortar(SBMM)were enhanced significantly as the amount of SB was increased from 5% to 20%.Temperature change had different effects on the properties of RM and SBMM.High temperature was beneficial to early flexural and compressive strength development of RM,but caused serious strength reduction at later stages.High temperature enhanced the development of tensile bond strength of RM.Increasing temperature enhanced properties of SBMM,including flexural,compressive,and tensile bond strength.Higher relative humidity improved all measured properties of all mortars.Scanning electron microscope(SEM)observations of the morphology of RM and SBMM at 360 d cured under different conditions accounted well for the changes in mechanical properties.

Elimination of Surfactants and Small Dyes from Water with Silicasupported Dendritic Amphiphiles

Silica-supported branched polyethylenimine（Sil@PEI） is a conventional adsorbent and shows a limited affinity to anionic surfactants and small dyes（K = 106？107 L/mol）. If the PEI is alkylated with cetyl groups（C16）, the K of the resulting adsorbents（Sil@PEI@C16-x, where x is the fraction of PEI units being alkylated） is significantly improved. Optimization shows that Sil@PEI@C16-0.15 can best reduce aqueous surfactants to a residue around 10？10 mol/L; while Sil@PEI@C16-0.6 can reduce even small aqueous dyes to a residue below 10？10 mol/L, nearly 105-fold lower than that by Sil@PEI. The adsorbents are well recyclable. It is believed that in the case of dyes, the dense cetyl shell can isolate the PEI from the bulky water and thus suppress the competitive binding by water; while in the case of surfactants, the semiclosed cetyl shell can simultaneously meet electrostatic complement and hydrophobic complement to the surfactants.

Facile anodization approach derived low-crystalline NiCoeOH/NiCoOOH composite films for ultra-high areal capacity and mass loading supercapacitors

The design of supercapacitor materials with both high areal capacity(C)and high mass loading is vitally important for enhancing energy density(E).Herein,we prepared a NiCosingle bondOH/NiCoOOH composite film consisting of NiCosingle bondOH/NiCoOOH nanosheets on an expanded graphite paper(EGP)by using a facial anodization method.The as-prepared NiCosingle bondOH/NiCoOOH film exhibits ultra-high C of 11 mA·h·cm^(-2)at a mass loading of 165 mg·cm^(-2),high rate capability of 71%and excellent cycling stability of 95%after 12000 cycles.The outstanding performance is ascribed to the low-crystalline feature of the NiCosingle bondOH/NiCoOOH nanosheets,and the synergistic effect of the NiCosingle bondOH and NiCoOOH phases and high conductive porous EGP.An aqueous asymmetric supercapacitor,assembled with the NiCosingle bondOH/NiCoOOH on EGP and Fe_(2)O_(3)on EGP as positive-and negative-electrode,respectively,shows a highest E of 3.8 mW·h·cm^(-2)at a power density(P)of 4 mW·cm^(-2)and a maximum P of 107 mW·cm^(-2)at an E of 2.7 mW·h·cm^(-2).

Recent advances in nacre-inspired anisotropic thermally conductive polymeric nanocomposites

The rapid development of miniaturized,highly integrated,and multifunctional modern electronic devices has generated a growing demand for anisotropic heat dissipation in polymer nanocomposites for thermal management applications.These anisotropic thermally conductive multifunctional polymer nanocomposites use bio-inspired structural design based on natural nacre,which is the gold standard for biomimetics.However,to date,a comprehensive review and critique on the highly-anisotropic thermal conduction of nacre-mimetic nanocomposites is nonexistent.As such,this extensive review of the nacre-inspired highly anisotropic thermal management nanocomposites summarizes the current design strategies,and explains the thermal conduction mechanisms,and factors affecting anisotropic thermal conductivity.Furthermore,the practical applications of the asprepared nacre-inspired highly anisotropic nanocomposites are highlighted.Finally,the key challenges and potential solution strategies associated with these nacre-inspired highly anisotropic nanocomposites are discussed and outlooks for future research opportunities are also proposed.

基于低成本TiN/生物碳泡沫的高效太阳能蒸汽发生器（英文）

利用太阳能产生蒸汽是净化污水或海水的有效方法.本文中,我们将氮化钛纳米颗粒沉积在经过碳化处理的木块上,得到一种新型的双层太阳能蒸汽发生材料. TiN纳米颗粒具有比以往报道过的光热转换材料(如等离子体金属、碳基材料和半导体纳米材料)更好的稳定性、更经济的价格、更低的毒性、更宽和更强的光吸收等多重优点. TiN纳米颗粒的沉积量以及基底的厚度和类型对水的蒸发速率和太阳能-蒸汽转换效率有重要影响.在模拟太阳光强度为1 kW m^(-2)下,该材料具有92.5%的太阳能-蒸汽转换效率,这是已知的木基光热转换材料中的最高效率.此外,该材料具有良好的可重复利用性.