To reveal the evolution of pore structure damage of cement-based materials under cyclic freeze-thaw (F-T) loads, a typical white cement mortar was used as a research object, and the pore structure of the mortar saturated with water under certain F-T cycles was characterized by the low-field magnetic resonance (LF-NMR) spectroscopy. Mortar specimens were cured at 20℃ and 80℃ to yield the different initial pore structures, and suffered from fast and low F-T loads. The results show that the F-T resistance of mortar decreases, the distributions of the gel pores and the macro-capillary pores increase, but those of the meso-capillary pores maintain when curing in hot water at 80℃. By contrast, F-T load has a slight impact on the gel pores and macro-capillary pores, and enhances the distribution of micro-cracks. The rate of rising the micro-cracks under F-T loads for the mortar specimens cured at 80℃ is greater than that for the mortar specimens cured at 20℃. F-T rate has little influence on the pore structure evolution of the mortar. The micro-crack ratio is bi-linearly related to the mass loss ratio. The internal deterioration and surface spalling of the mortar under F-T loads are mainly induced by the generation and development of the micro-cracks in the mortar matrix, showing no direct association with the gel pores and macro-capillary pores.

A three dimensional(3D) model and a thin-film model were proposed for the glass ribbon forming process in float process. The forming process of glass ribbon in a 600 t/d tin bath was simulated via a software named Ansys Polyflow. Compared to the 3D model, the thin-film model is demonstrated to be more accurate and effective for the simulation of glass ribbon forming process. According to the simulation results, the forming process of glass ribbon in each zone of the tin bath was discussed. The influences of longitudinal and transverse temperature distributions on the forming process were analyzed for glass ribbons with different thicknesses. Finally, the optimized forming temperature condition is obtained for glass ribbon with a thickness of 4 mm or 10 mm, respectively.

A creep prediction model of concrete considering the viscoelasticity of interface transition zone was proposed based on the Laplace transform principle to analyze the influence of interface transition zone on the creep performance of concrete. The proposed model was compared with a model of concrete creep non-considering interface transition zone and verified by the related experiments. The results show that the data predicted by the concrete creep model considering the interfacial transition zone is consistent with the experimental results. The model can be used to analyze the effect of interface transition zone on the creep properties of concrete besides the experiments. The specific creep of concrete specimens with different fly ash contents (i.e., 0, 30% and 60%) is increased by 45.7%, 25.1% and 66.7%, respectively, when the loading age is 365 d due to the interface transition zone. The contribution of the interface transition zone of concrete specimens with different fly ash contents to the creep of concrete at different loading ages was analyzed via the prediction by the model. The interfacial transition zone of concrete with fly ash to the concrete creep contributes greater than that without fly ash. The interface transition zone of the baseline group in the later period has an increasing contribution to the concrete creep due to the continuous weakening of the interface transition zone under the load. For the concrete specimens with fly ash, the interface transition zone continuously enhances and the contribution of the interface transition zone to the creep of concrete continuously reduces with the increase of loading age because of the fly ash secondary hydration. The analysis of the influence of interface transition zone parameters on the concrete creep indicates that the concrete creep of different interface transition zones can be well described when the interface transition zone elasticity constant is in the range of 0.000 1<E_itz<0.01 and the viscosity coefficient is in the range of 0.1<η_itz<10.

Cementitious composites are inevitably to be cracked in engineering structures due to their inherent brittleness and low tensile strength. The capsule-based self-repairing system provides a feasible method for repairing and delaying the potential damage of cement-based material matrix. The occurring, spreading and fracturing process of micro-cracks and microcapsules fracture behavior in the self-repairing model material were simulated by an extended finite element method, and the hitting probability was validated. Meanwhile, the effective elastic modulus of self-repairing cementitious materials before and after repairing by spherical/spherical microcapsules with different contents was calculated via composite materials theory, and the repairing efficiency was characterized.

HZSM-5 zeolite was modified with levulinic acid produced in situ via glucose hydrolysis, and the catalysts were characterized by X-ray diffraction, X-ray fluorescence spectroscopy, N₂ adsorption-desorption, scanning electron microscopy, NH₃-temperature programmed desorption, Fourier transform infrared spectroscopy and thermal analysis. The catalytic performance was evaluated in a fixed-bed micro reactor. The results show that the modified HZSM-5 catalyst has a microporous-mesoporous structure based on the retaining complete crystal structure, its acid content and acid strength decrease and the ratio of B acid to L acid increases, which are conducive to improving the catalyst longevity, oil yield and total selectivity of benzene, toluene and xylene (BTX). At 410℃, 0.1 MPa and methanol (WHSV) 2.2 h^-1, the longevity of modified HZSM-5 catalyst reaches 174 h, the oil phase yield is 23.84%, and total selectivity of BTX is 61.39%. Compared to the unmodified catalyst, the longevity of modified HZSM-5 catalystis increased by 144 h, oil yield is increased by 7.29%, and total selectivity of BTX is increased by 3.42%.

Influence of silane emulsion hydrophobic agent as an additive on the strength and capillary water absorption behavior of concrete was investigated through strength test, hydration heat test, thermogravimetric analysis, capillary water absorption and mercury intrusion test. The results show that silane emulsion reduces the early-age compressive strength and splitting strength of concrete, which is mainly attributed to the retardation effect of silane emulsion on the early cement hydration. The capillary pore volume in 28-d harden cement paste is increased by adding silane emulsion because of the depressed cement hydration. However, the initial water absorption rate, the secondary water absorption rate and the total amount of water absorption of the 28-d concrete during capillary water absorption process are greatly reduced by silane agent. This is since silane emulsion reacts with cement hydration products to form an alkyl hydrophobic layer on the pore wall of the capillary pores, which changes the surface property of the wall from hydrophilic to hydrophobic, thus significantly reducing the rate and the amount of water absorption of concrete. Silane agent has a more profound influence on the concrete properties with a higher water-cement ratio due to the lager capillary pore volume.

Lightweight ultra-high performance concrete (LUHPC) was prepared with pre-wetting lightweight aggregate, Portland cement, silica fume, fly ash microsphere, steel fiber and expansion agent as raw materials. The influencing factors on the performance of LUHPC and the developing mechanism were investigated. The results show that the as-prepared LUHPC has a superior performance. The LUHPC can be self-compacting and has a low dry apparent density of 2 040 kg/m³. The 28-d compressive strength and flexural strength are 120 MPa and 18 MPa, respectively. The bending toughness index is 21.8, and the 56-d shrinkage rate is 2.62×10^-4. The superior performance of the LUHPC is mainly due to the ball effect of fly ash microsphere, the lightening, internal curing, "arch-shell" structure effects of pre-wetting lightweight aggregate and the shrinkage-compensating effect of expansion agent.

To clarify the dissolution behavior of K-containing silicate fertilizers produced by high-temperature sintering under acidic condition, the chemical element release and mineral evolution were investigated at ambient temperature in the extractants of hydrochloric and citric acids based on the chemical reactions of minerals contained in silicate fertilizer with acids. The results show that the more elements are released at a lower pH value of extractant. 2% citric acid with pH 2.1 is significantly more effective in dissolving the silicate fertilizer than hydrochloric acid with the same pH value. The dissolution rate of silicate fertilizer in hydrochloric acid at pH value of 0.3 is maximum, and only a mineral detected in the filter residue is leucite. Kaolinite and gibbsite are formed in the reactions of kalsilite and gehlenite with acid. Aluminum release is due to the further reactions of kaolinite and gibbsite with acid.

Foam concrete as one of the most widely used and investigated construction materials with integrated structural insulation has various unique properties such as low self-weight, fire resistance and air borne sound insulation. The compressive strength and thermal conductivity of foam concrete are the key factors affecting the application. The compressive strength of foam concrete increases while the thermal conductivity decreases with the increase of the density, thus hindering the application. In this review, the effects of foaming agent, density, porosity, admixture and water cement ratio on the compressive strength and thermal conductivity were discussed. Recent research work on lightweight foam concrete and integration of thermal insulation structure foam concrete were summarized. The existing problems (i.e., collapse of the slurry, incompatibility of mechanical and heat preservation properties and low durability) and the corresponding solutions to the problems were given. This review could provide a basis for future investigation and practical engineering application.

An appropriate amount of carbon nanotubes can be added into cement-based materials to obtain the unique conductive properties (i.e., self-sensing and intelligence of cement-based material). The electrical conductivity of carbon nanotube cement-based composites is affected and restricted by some factors such as physical field and material composition. Some recent works on influencing factors on electrical conductive properties of carbon nanotubes-reinforced cement based composite materials were reviewed. For the electrical indicators such as resistivity and current of composites, the mechanism of the physical field influencing the conductive properties of composites was analyzed. The effect of material component on the conductive mechanism of carbon nanotube cement-based composites was discussed. The problems to be further investigated were proposed, and the future research and trends of the conductive properties of carbon nanotube cement-based composite materials were prospected.