The influence of hydroxyethyl methyl cellulose (HEMC) on the early hydration of Portland cement and rapid-hardening calcium sulfoaluminate cement (CSA) was investigated by acoustic and electroacoustic spectrometer and low-field NMR instrument. The water retention and air void content of fresh mortars were analyzed. The results show that regardless of cement variation, the water retention and air void content are improved after the addition of HEMC. The change of zeta potential is related to cement type. For the Portland cement paste, the addition of HEMC greatly shortens the time of zeta potential becoming electropositive, and the absolute value of ζ potential for rapid-hardening CSA paste decreases slightly. In addition, the T₂ distribution of HEMC containing cement pastes also appears a relaxation peak at 100-1 000 ms. Such a peak disappears after 3-d hydration for the Portland cement, while it only disappears in 120 min for rapid-hardening CSA, indicating that HEMC exerts a weak adsorption on the surface of rapid-hardening CSA particles. Unlike the retardation effect of HEMC on the Portland cement hydration, HEMC hardly affects the early hydration heat release of rapid-hardening CSA.

Effects of water-binder ratio, polycarboxylate superplasticizers (PCEs) with different molecular structures, super-absorbent polymer (SAP) and an anionic viscosity modifying agent (VMA) on the rheological properties of mortar were investigated. The results show that increasing the water-binder ratio simultaneously reduces the yield stress and plastic viscosity of mortar and increases the fluidity retention capacity. The addition of PCE reduces the yield stress of mortar and the steric hindrance induced by the side carbon chains is one of the main reasons for the dispersion effect of PCE. The side carbon chains inhibit the adsorption of PCE on the surface of cement particles. Increasing the length of the side chains of PCE has little effect on the initial rheology. SAP increases the yield stress and plastic viscosity of mortar by reducing its free water content, and its action mechanism is the same as reducing the water-binder ratio. VMA improves the yield stress of mortar due to the bridging effect at low dosages, but has little effect on the plastic viscosity. At high dosages, the bridging effect of VMA weakens but the viscosity of liquid phase greatly increases, thus decreasing the enhanced effect on the yield stress of mortar and greatly increasing the plastic viscosity of mortar.

The molecular size of cellulose ether in solution was determined via dynamic light scattering (DLS), and the adsorption of cellulose ether on cement particles was determined by total organic carbon content (TOC). The results show that the particle size of cellulose ether in solution decreases with the increase of concentration and tends to a constant value, which can be called as undisturbed diameter. There exists a correlation between the measured adsorption of cellulose ether from TOC and theoretical adsorption of single layer cellulose ether in the state of dense packing on the surface of cement particles calculated from its undisturbed diameter and the Blaine specific surface area of cement. Therefore, cellulose ether is most probably adsorbed on the surface of cement particles with its undisturbed diameter, which is independent of cement type obtained.

The interfacial interaction between defoamer and air entraining agent was investigated by calculating the composition of mixed interfaces, the interaction parameter (β), and the free energy of additional adsorption and comparing the solution and hardened mortar performance of defoamer and air entraining agent in various proportions. The results show that compounding a suitable defoamer in a certain proportion into air entraining agent increases the interfacial free energy of the bubbles, resulting in a decrease in the stability of the foam and the air content of the mortar. The defoamer can also effectively reduce the air-void diameters and spacing factors of the hardened mortar, and improve the compressive strength of the mortar.

A mechanical model of cement and emulsified asphalt mortar (CA) from four different levels (i.e., cement hydration products, cement gel skeleton, cement asphalt composite system and CA mortar) was proposed based on the microscopic experimental results by backscatter electron imaging and X-ray diffraction and the Hashin composite ball model. The relationships among the elastic modulus of CA mortar, compressive strength f and composition parameters were investigated. The results show that the volume fraction of cement hydrate phase is an important parameter affecting the CA mortar elastic modulus and the compressive strength f. When asphalt is regarded as a pore or a low modulus component, the static elastic modulus of the CA mortar and the volume fraction of cement hydrate, compressive strength f and gel-space ratio all have a power function relationship > 0.8. The cement hydrate in the CA mortar is still a continuous phase and constitutes the composite gel skeleton, asphalt interspersing among them, and the contribution of asphalt to the CA mortar strength and elastic modulus is relatively low.

Effects of aspect ratio and volume fraction of straight steel fiber on the modulus of elasticity (MOE), compressive strength, and flowability of ultra-high-performance concrete (UHPC) were investigated. The results show that the MOE and compressive strength of UHPC increase and the flowability of the fresh UHPC decreases with the increase of fiber volume and fiber aspect ratio. Steel fiber has both positive and negative effects on the MOE of UHPC. The positive effect of steel fiber is due to the high elastic modulus of steel fiber itself. The negative effect is caused by the decrease of the MOE of UHPC matrix due to the decrease of the flowability of fresh UHPC and the increase of the porosity and the inner defects after the fibers adding into the matrix. A semi-empirical formula was proposed for predicting the MOE of the UHPC based on the experimental data, comprehensively considering the positive and negative effects of fibers. It is indicated that the MOE of the UHPC could be strongly correlated to the compressive strength.

The mechanical properties and flexural toughness behaviors of steel fiber reinforced shotcrete containing different liquid setting accerlerators were evaluated by a three-pointing loading method. To clarify the working mechanism of liquid setting accelerators on the toughness properties of steel fiber, the early-age strength development and steel fiber-cement matrix interface area micromorphology of steel fiber reinforced mortar with the similar material composition were investigated. The results show that the long-term mechanical strength of steel fiber reinforced shotcrete with alkali-free accelerator is greater than that with alkaline setting accelerator, thus leading to a full loading-deflection curve and better toughness enhancement effect of steel fiber. For the early-age strength development, short prismatic ettringite and needle-like C-S-H gel appear after introducing alkali-free setting accelerator, thus inducing the better bonding strength between steel fiber and cement matrix and improving the initial support capacity of steel fiber reinforced shotcrete.

A reactive powder concrete (RPC) matrix with a low water to cement ratio of 0.21 was prepared. The hydration of the RPC matrixes under long-term hydrothermal condition was investigated. The insoluble matter of the RPC matrix was examined to characterize its hydration level. The structural property of the RPC matrix was characterized using the Vickers hardness meter. The phase composition and morphology of the RPC matrix were characterized using X-ray powder diffraction and scanning electron microscopy/energy dispersive spectrometry. Under the hydrothermal condition, the hydration level of the RPC matrix increases during the autoclaved curing for 0-96 h, and the Vickers hardness of the RPC matrix also increases. The hydration rate of the RPC matrix is rather low, and the hydration of the clinker in the matrix becomes stopped during the long-term autoclaved curing (i.e., 168-312 h). In addition, there are a few crystalline hydrates in the RPC matrix cured for long-term, and the flocculent calcium silicate hydrates gel cannot be transferred to their crystalline forms due to the lack of space for the crystallization. The RPC matrix with a low water to cement ratio has a great stability under the long-term hydrothermal condition and a promising potential to be used as nuclear waste keeping materials.

Silane impregnation is commonly used as a durability protection measure for concrete. Cement-based materials impregnated with triethoxyisobutylsilane were analyzed by pyrolysis-gas chromatography-mass spectrometry (PGC-MS) to identify the characteristic structure and amount of impregnation. The main component of the pyrolysis fragments is isobutyl. The water vapor sorption isotherm (WVSI) was determined to investigate the interaction between moisture and the impregnated materials. There is no notable difference at a humidity of <30%, the pore condensation (adsorption) and "ink-bottle" effect (desorption) substantially decrease, and the adsorption/desorption rate increases due to the impregnation at a humidity of>60%. The Xenon lamp ageing (10 weeks) after laboratory accelerated ageing process does not change the silane content and the WVSI characteristics.

The relationships among the fluidity, setting time, and pH value of hydrated magnesium silicate (MgO-SiO₂-H₂O, M-S-H) prepared by silica fume (SF) and MgO after calcination at different temperatures were investigated, and the strength and shrinkage characteristics of M-S-H cementious materials were analyzed. The effect of MgO on the hydrated products of MgO-SF and the structure of M-S-H at different calcination temperatures was investigated by X-ray diffraction and thermogravimetric analysis. The results show that the intensity of MgO diffraction peak increases, the peak width becomes narrower, the grain size increases, and the activity decreases as the calcination temperature increases. The contents of Mg(OH)₂ and M-S-H in the pure pulp prepared by calcining MgO at 1 150 ℃ are the highest, and the degree of polymerization of M-S-H silicon tetrahedron becomes the maximum value. The MgO-SF pulp and mortar slump prepared by calcining MgO at 1 150 ℃ are 129 mm and 206 mm, respectively, in accordance with the large-flow concrete. The pH value and setting time of the pulp are moderate, the mortar strength is high, and the dry shrinkage rate (ε_t) is the minimum value. ε_t is positively correlated to the change in Mg(OH)₂ content.

Chloride-induced corrosion is one of the major deterioration mechanisms of reinforced concrete that may seriously affect the durability of the structures in marine environment. The deterioration of concrete durability as a long-term process is usually investigated by lab-scale artificial acceleration simulation. However, there is no normative standard in the corresponding test methods, test systems and acceleration factors in the indoor simulation and coastal exposure research on concrete durability, thus restricting the engineering application of the research results. It is necessary for the durability of concrete structure research more practical engineering significance to establish the similarity relationship of chloride ion ingress into concrete between the coastal exposure environment and the indoor simulated environment. It could accurately evaluate the durability and predict service life of concrete structures in the marine environment. From the viewpoints of single factor and multi-factor effects, the available experimental, theoretical analysis and numerical simulation of the similarity of chloride ion ingress into concrete were introduced, respectively. The research findings on the similarity of chloride ion ingress into concrete exposed to marine environment were summarized. The relevant discussion and expectation of this subject were conducted, thus providing a basis for future theoretical research and practical engineering application.

Carbon nanotube is a kind of excellent nanomaterial. The incorporation of carbon nanotubes will affect the microstructure and macroscopic properties of cement-based materials. The research results about carbon nanotubes on the microstructure and durability of cement-based materials were analyzed. The effect of carbon nanotubes on the hydration characteristics, pore structure, micro-crack, internal interface, carbonization resistance, ion erosion resistance, frost and thaw resistance of cement-based materials and their mechanism were discussed. The results show that carbon nanotubes promote the generation of hydration products through nucleation and affect the hydration reaction rate of cement. The pore structure and internal interface of cement-based materials were optimized by the filling and bridging effects of carbon nanotubes, thus hindering the forming and expanding of micro-cracks Also, carbon nanotubes can improve the durability of the cement-based materials, such as carbonization resistance, ion erosion resistance, frost and thaw resistance via the optimization of the microstructure of the cement-based materials. At present, some further researches are thus needed since the research results of carbon nanotubes on the microstructure and durability of cement-based materials are relatively less and the relevant conclusions obtained are different.

The viscosity of Ge₁₀As₄₀Se₅₀ chalcogenide glass was investigated by fiber elongation and rotation methods. The Vogel-Fulcher-Tammann equation was proposed as an optimal fitting model after comparing to the accuracy of different equations. Ge_xAs_ySe_1-x-y glasses were compared according to the fragility, m, derived from the Angell plot. The network structure of Ge₁₀As₄₀Se₅₀ chalcogenide glass was investigated by X-ray photoelectron spectroscopy (XPS). The results show that the fragility change of Ge_xAs_ySe_1-x-y glasses follows the topological constraint theory in the range of the average coordination numbers (i.e., r=2.0-2.6). The m of Ge_xAs_ySe_1-x-y glasses decreases as r increases. However, the m does not strictly decrease as r increases when r is greater than 2.2. Based on the XPS results, Ge₁₀As₄₀Se₅₀ chalcogenide glass exists Se chain in the network structure, thus affecting the stability and results at a greater m.

TiO₂/Ti₃C₂T_x composites were synthesized by a solvothermal method with Ti₃C₂T_x as substrate and isopropanol (C₃H₈O) as an inducer. The phase composition and microstructure of TiO₂/Ti₃C₂T_x were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and ultraviolet-visible diffuse reflectance spectroscopy. The results show that anatase type TiO₂ is uniformly grown on the layered surface of Ti₃C₂T_x, thus improving the electron transport performance of TiO₂/Ti₃C₂T_x composites. The optimum photocatalytic performance of TiO₂/Ti₃C₂T_x-24 h can be obtained under the irradiation of 500 W mercury lamp (365 nm UV light), and the degradation efficiency of methyl orange (MO) is 95% for 75 min, which is 67.7% greater than that of pure TiO₂ photocatalyst.

Cu/Fe-layered doubled hydroxide (CuFe LDH) prepared by a coprecipitation method was used to degrade methylene blue (MB) and ammonia as a heterogeneous photoactivator of NaClO. The micro-morphology, reaction kinetics and degradation mechanism were investigated. The layered structure of the samples with Cu/Fe molar ratios from 2∶1 to 4∶1 was analyzed. The catalyst with Cu/Fe molar ratio of 3∶1 exhibits the optimum performance under given conditions (i.e., catalyst dosage of 0.5 g/L and NaClO of 0.075 mL), and the pseudo-first-order rate constant of 30 mL MB (100 mg/L) is 7.9 times greater than that without any catalyst. 30 mL ammonia (100 mg/L) at the catalyst dosage of 3 g/L and NaClO of 0.3 mL can be degraded by 99.5% within 1 min, compared to that of 66.6% without any catalyst. Based on the radical quenching experimental results, the superoxide radicals are the dominant reactive oxidants, and also involve chlorine radicals and hydroxyl radicals. The results by electrochemical impedance spectra and X-ray photoelectron spectroscopy reveal that the photoelectrons can accelerate the in-situ regeneration of reaction activity sites on the surface of catalyst and increase the separation efficiency of photo-induced charges in CuFe LDH/NaClO/light system, resulting in the improved degradation of waste water pollutants.

Different rare earth ions (i.e., Nd³⁺, Y³⁺, Eu³⁺) doped BiVO₄ nanocrystals were synthesized by a chemical protocol method. The phase composition, crystal structure, morphology, local structure, surface chemistry and spectral properties of the nanocrystal samples were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, ultraviolet-visible diffusion reflective spectroscopy and photoluminescence spectroscopy. The results show that the sizes of different ion-doped BiVO₄ crystals are in nanoscale, the BiVO₄ nanocrystals doped with different ions have a tetragonal crystal structure. and the obtained nanocrystals have regular morphologies and clear profiles, indicating that the obtained nanocrystals have a good crystallization performance and exhibit a certain degree of lattice distortion. Raman peaks of doped BiVO₄ nanocrystals appear at about 247, 367, 763 and 855 cm^-1, which are consistent with the characteristic vibration frequencies of BiVO₄ structure with tetragonal phase. UV-visible diffuse reflectance spectrum shows that the internal electronic structure of the BiVO₄ nanocrystals changes after doping ions, the band gap energies of BiVO₄, Eu:BiVO₄, Y:BiVO₄ and Nd:BiVO₄ nanocrystal are 2.50, 2.74, 2.90 and 2.94 eV, respectively, indicating that doping different ions could regulate the band gap of the semiconductor nanocrystals. Based on the results by photoluminescence spectroscopy, the minimum luminescence intensity of Eu:BiVO₄ nanocrystals is obtained, showing the minimum electron hole recombination efficiency, which is suggested that the Eu:BiVO₄ nanocrystals has higher photocatalytic activity. The maximum luminescence intensity of Y:BiVO₄ nanocrystal is obtained, thus having the maximum electron hole recombination efficiency.

Calcium polyphosphate (CPP) was modified via the Schotton-Baumann acylation reaction using 12-aminododecanoic acid (12-AA) and acryloyl chloride as main raw materials. The effects of hydrothermal reaction time and 12-AA dosage on the modification process of CPP were investigated. They were characterized by Fourier infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The particle size, contact angle and thermal stability of CPP were also determined. The results show that the yield of CPP-modified increases with increasing the hydrothermal reaction time and 12-AA content. In the acylation process, the pH value decreases as the reaction time increases until stable (i.e., a weak acidity, pH 6.2). A greater yield (i.e., 56.70%) and the smaller particle size (i.e., 588.3±119.7 nm) of modified CPP are obtained when a molar ratio of CPP to 12-AA is 1∶3 and the reaction time is 12 h. The contact angle before and after the modification increases from 2 to 61.41 degrees. Based on the results by thermogravimetric analysis, the CPP has a good thermal stability with little mass loss at <592.92 ℃. However, the modified CPP still has a good thermal stability and shows an obvious mass loss at 426.68-461.66 ℃.

ATP/g-C₃N₄ (graphitic carbon nitride) consisting of g-C₃N₄ film in-situ growth on the surface of attapulgite (ATP) rod was prepared via a hydrothermal process. Then ATP/g-C₃N₄ was used as a carrier to uniformly load LaCoO₃ nano-particles to prepare Z-scheme ATP/g-C₃N₄/LaCoO₃ heterojunction photocatalysts. The samples obtained were characterized by X-ray diffraction, transmission electron microscopy, ultraviolet-visible, photoluminescence, Brunauer-Emmett-Teller, specific surface area analysis and photo electrochemical analysis. The oxidative removal ability of ATP/g-C₃N₄/LaCoO₃ at different loadings of LaCoO₃ to benzothiophene (DBT) in model gasoline was investigated under visible light. The results show that ATP/g-C₃N₄/LaCoO₃ composites dramatically enhance the visible light response, the absorption capacity and the separation of photogenerated electron-hole pairs, compared to ATP/g-C₃N₄ andLaCoO_3. After 150-min irradiation, the desulfurizing rate of 50%-ATP/g-C₃N₄/LaCoO₃ can achieve 85.3%.

The SiO₂ in the molybdenum tailings is purified by high-temperature heating and pickling, and the surface is modified with methylhydrogen-containing silicone oil and dimethyl diethoxysilane(DDS).The results show that the impurities such as calcium and magnesium can be effectively removed, and the purified content of silicon oxide can reach 84.3%. When methyl hydrogen-containing silicone oil is used as a modifier, the activation degree of modified slag can reach 77.6%, and the maximum contact angle can reach 116°. Methyl hydrogen-containing silicone oil can be effectively grafted onto the surface oftailing particles. When dimethyl diethoxy silane is used as a modifier, the activation degree can reach 95%, the contact angle can reach 130°, and dimethyl diethoxy silaneis uniformly coated on the surface of tailing particles. The application of modified molybdenum tailings silica in ammonium hydrogen phosphate extinguishing agent shows that it can improve the water repellency of ammonium hydrogen phosphate extinguishing agent.

Carbon foams were prepared via molten salt-assisted combustion synthesis with polyvinyl chloride (PVC) as a carbon source, magnesium powder (Mg) as a reducing agent, ferrocene (Fc) as a catalyst and different kinds of molten salts (i.e., NaCl, KCl, and MgCl₂) as a porogen. The products were characterized by X-ray diffraction, scanning electron microscopy, Raman spectroscopy and specific surface area measurement. The electromagnetic shielding specimens were prepared with carbon foam as an absorbent and paraffin as a binder. The electromagnetic shielding effectiveness of the samples in the frequency range of 8.2-12.4 GHz was tested by a rectangular waveguide method. The results show that the optimum foaming effect is achieved when NaCl is used as a porogen, and the well-developed hollow spherical carbon foams with the pore sizes of 100-500 nm are obtained after washing and leaching. Molten salts have a positive effect on the graphitization degree and micro-morphology of carbon foams, in which NaCl shows an optimum accelerating-effect. The combustion synthesized products have a good electromagnetic shielding performance. The carbon foams with NaCl as a molten salt have an optimum electromagnetic shielding efficiency (i.e., up to 39.5 dB).

A hypothesis on 'centroplasm of cement-based composite' was proposed by Wu Zhongwei 60 years ago. Although his hypothesis is rather advanced, it has not been clarified so far. The innovation of the hypothesis is to break the conventional boundaries between cement chemistry and concrete chemistry. In his hypothesis, concrete should be regarded as a holistic system with hierarchy and openness. Effect of interface between centroplasm and matrix is extended to be negative and positive. Pore is considered as a negative centroplasm although it is "empty", thus being benefit to some properties of products. In addition, his hypothesis also gives the corresponding model and some further research aspects.