(Ba_1-xMe_x)_1.95SiO₄:0.05Eu (Me=Ca, Mg) phosphor was synthesized in a reducing atmosphere by a high-temperature solid-phase method. Ca²⁺ and Mg²⁺ solubilities in Ba₂SiO₄-phase should be 10% (mole fraction, the same below) and 30%, and the solid solution induces an increase in green fluorescence brightness under ultraviolet excitation. The intensity of (Ba_0.9Ca_0.1)_1.95SiO₄:0.05Eu and (Ba_0.7Mg_0.3)_1.95SiO₄:0.05Eu phosphors is 110% and 140% greater than that of Ba₂SiO₄:Eu under 365 nm, and 105% and 125% greater than that of Ba₂SiO₄:Eu under 254 nm. Based on the analysis by X-ray diffraction, (Ba_1-xCa_x)_1.95SiO₄ (0.1<x≤0.3) is T-phase but not Ba₂SiO₄-phase. Ca²⁺ or Mg²⁺ substitution does not decrease in cell volume but causes the better crystallization (i.e., the diffraction peak is higher, and the half-width is more narrow). Further more, b decreases a little more quickly than c, indicating that Eu²⁺ ions prefer 9-coordinated Ba²⁺(II) sites more than 10-coordinated Ba²⁺(I) sites. According to the high-resolution photo luminescent spectra, Eu²⁺(I) contributes more than Eu²⁺(II) for the green luminescence intensity. Moreover, Eu²⁺(I)/Eu²⁺(II) ratio increases as Ca²⁺ or Mg²⁺ solubility increases. The high-resolution X-ray photoelectron spectra of Eu4d indicate that the valence of Eu is rarely changed after cation substitution. Ca²⁺ or Mg²⁺ substitution can improve the crystallinity, promote Eu²⁺ to enter Ba²⁺(I) site(which would has higher luminescent efficiency) and keep Eu ion valence stable due to the improvement of phosphor luminescent intensity by cation substitution.

A low-temperature early-strength accelerator was designed with three components, such as calcium bromide (CaBr₂), lithium bromide (LiBr) and triisopropanolamine (TIPA). Effect of early-strength accelerator on the strength, setting time and fluidity of cement paste at a low temperature was investigated, and its mechanism of action was discussed based on the perspectives of hydration heat and product microstructure. The results show that the incorporation of low-temperature early-strength accelerator shortens the initial and final setting time of cement pastes, and accelerates the strength development of specimens at a low temperature (i.e., 5 ℃). The 1-d, 3-d, 7-d and 28-d compressive strength of cement pastes mixed with the low-temperature early-strength accelerator can be increased by 291%, 78%, 62% and 40%, respectively, and the strengthat each age after 3 d already exceeds that of the contrast sample cured at 20 ℃. At a low temperature, the early-strength accelerator can shorten the hydration induction period of cement hydration and advance the acceleration period. Furthermore, the maximum heat release rate can be increased by 78%, compared to the contrast sample. The cumulative heat release is increased by 227% and 52% at 12 h and 7 d, respectively. The early-strength accelerator can also promote the hydration reaction at the initial stage of cement hydration, increase the content of Ca(OH)₂ in the sample and increase the hydration degree. Large amounts of Ca(OH)₂ are formed in the products at the age of only 12 h, and some products, such as bromine-containing C-S-H gels and hydrated calcium bromoaluminate (Ca₄Al₂O₆Br₂·10H₂O), are also generated. Large amounts of hydration products are accumulated, refining the pore diameter of the specimens at the initial stage of hydration (before 7 d) and decreasing the number of macropores. The total porosity of the cement pastes at 1 and 7 d is decreased by 16% and 31%, respectively, thus leading to the denser microstructure.

Malic acid was used as a modifier of foamed magnesium oxysulfate cement (FMOSC). Effect of malic acid on porosity, dry density, compressive strength, softening coefficient and drying shrinkage of FMOSC was investigated. The phase composition, cross-section morphology and elemental composition of FMOSC were studied by X-ray diffraction, infrared spectra and scanning electron microscopy. The results show that the addition of malic acid has slight influence on the dry density and porosity of the sample, but the pore size distribution becomes narrow and the drying shrinkage rate reduces. The compressive strength of FMOSC modified with malic acid is twice greater than that without malic acid. It is indicated that malic acid could inhibit the formation of Mg(OH)₂ by chelation ability and promote the growth of 517 crystal phase in the form of screw dislocation.

In order to reveal the characteristics of nano-sized silica sol grout for fractured rock grouting and the temperature effect on the gelation time for nano-sized silica sol grout, the influences of accelerator dosage and temperature on the gelation time were investigated. The results show that the gelation time decreases exponentially with the increase of accelerator dosage and temperature. The gelation time equation of silica sol grout with respect to the temperature effect was proposed. The real-time consistency equation and real-time permeability equation were derived. To design the grouting parameters, the amount of nano-sized silica sol grout and accelerator could be confirmed, and the target penetration length and formation conditions were confirmed. Finally, the grouting pressure was adjusted and the grouting time was calculated.

The influence of nano-metakaolin on the compressive strength of concrete under the coupled effect of Salt Lake brine and dry-wet cycles was investigated, and the mechanism was analyzed by mercury intrusion analysis, X-ray diffraction, infrared spectroscopy, scanning electron microscopy and energy dispersive spectroscpy. The results show that the proportion of nano-metakaolin has a great effect on the compressive strength of concrete under dry-wet cycles, and more than 2% nano-metakaolin decreases the loss rate of compressive strength. The modification mechanism is since nano-metakaolin reduces the proportion of harmful holes in concrete, improves the pore size distribution and makes the microstructure of concrete more compact. The erosion depth and intrusion amount of Cl, Na, Mg and S ions in concrete are reduced due to the presence of nano-metakaolin, thus decreasing the content of NaCl in the corrosive layer of concrete and preventing the concentration of corrosion products such as Mg(OH)₂, and CaSO₄·2H₂O. In consequence, the damage degree of concrete modified by nano-metakaolin with the coupled effect of brine and drying-wetting cycles decreases.

To study the influence of unsaturated carboxylate on the dispersing and flow releasing ability of slow-release polycarboxylate superplasticizer(PCE), the hydrolysis behaviors of carboxylates in sodium hydroxide solution at pH value of 12.0 was investigated, and the constants of hydrolysis rate were derived via a linear fitting. Mini slump was used to examine the variation of flow of cement pastes containing the synthesized slow releasing PCE over time, and the results were compared and analyzed to coordinate the relationship of hydrolysis behaviors of carboxylates and slow-release effectiveness of PCE. The results indicate that PCE with the substitution of acrylic acid with 33.3% methyl acrylate and 25.0% dimethyl itaconite showed significant slow-release effect, the initial fluidity of cement paste was 149 mm and 104 mm afterwards increased to 223 mm and 212 mm after 2 h respectively. PCE with carboxylate monomer of faster hydrolysis rate exhibited quicker flow releasing property, and PCE with carboxylate monomer containing more ester grouped manifested stronger flow releasing ability, but need longer time. The flow releasing property of PCE not only depended on the hydrolysis rate and ester group amount of monomer, but also related to its reactivity of monomer to match the copolymerization system.

The adiabatic temperature of ferric oxide aluminothermic system was analyzed based on the thermal dynamic theories. The results indicate that the boiling point of iron (i.e., 3 148.2 K) is an adiabatic temperature of different ferric oxide aluminothermic system (i.e., FeO/Al、Fe₂O₃/Al and Fe₃O₄/Al) under the standard condition. The gas phase conversion rate of iron product is different, i.e., 20.6% for FeO/Al, 21.3% for Fe₂O₃/Al and 2.0% for Fe₃O₄/Al. The adiabatic temperature and phase conversion rate decrease after adding diluent of ferroalloys into the thermits. According to the Fe₂O₃/Al thermit, the addition amount of ferroalloys (i.e., 0-1.35 mol and 3.75-5.10 mol) can control the phase conversion rate for gas phase of iron product and liquid phase of alumina product, correspondingly. The combustion wave can be self-propagated by preheating reactants when the adiabatic temperature is lower than 1 800 K after adding ferroalloys diluents. More addition amount of ferroalloys follows higher pre-heating temperature.

The durability of the concrete under salt-freezing environment is rapidly degraded due to the coupling effect. In this review, the research results of chloride transport under freeze-thaw cycles were summarized according tothe mechanical behavior, the diffusivity of chloride and several protective measurements. In freeze-thaw action, the concrete damage could be divided into two stages, and the two-stage damage theory was proposed to describe the initial and diffusion of damage, respectively. Some experimental methods were used to quantitatively investigate the damage degree of concrete. The relationships between damage degree and diffusion coefficient wereestablished to deal with the acceleration effect of freeze-thaw cycle on chloride transport. The influence of influencing factors on the chloride transport under freeze-thaw cycle was investigated. The existing studies are mostly obtained from lab-scale experiments, thus restricting the quantitative evaluation of the life of actual concrete structures. A series of protective measures, such as surface treatment, electrochemical rehabilitation/protection and addition of admixture were proposed, and afuture research direction in this field was discussed based on three aspects, i.e., experiment, theory and modelling.

Testing the early-age shrinkage deformation of cement-based materials is the basis to estimate the risk of cracking correctly. In fact, there exists no uniform on the autogenous shrinkage test in China. This review analyzed the articles testing autogenous shrinkage with corrugated tubes based on the volume-to-length conversion coefficient, the time-zero of autogenous shrinkage, the characteristics of early micro-expansion, the friction between corrugated tube and ground, the sealing property of the end corrugated tube, the control of testing temperature and the testing apparatus. Some vague concepts in the existing research were discriminated when the corrugated tubes method was compared with other methods, giving some suggestions for the future application of the corrugated tubes method in China.

A T-Na nanocompound gel was prepared with tris (chlorisopropyl) phosphate (TCPP) and sodium montmorillonite (NaMMT). The effects of TCPP/NaMMT mass ratios, moisture content and temperature on the gelation were investigated. The stability and nano-structure of nanocompound gel were characterized by X-ray diffraction, thermogravimetric analysis and transmission electron microscopy (TEM). The adsorption of T-Na nanocompound gel on organic solvents such as toluene was analyzed. The dispersion of layered NaMMT in TPU/T-Na composites was determined by TEM. The flame retardant effect of T-Na nanocompound flame retardant on thermoplastic polyurethane (TPU) was investigated by a cone calorimeter (CONE). The results show that the stable nanocompound gel is formed and the interlayer spacing of NaMMT increases from 0.98 nm to 3.15 nm when the mass ratio (TCPP/NaMMT) ranges from 2:1 to 7:1. The presence of moisture and the higher temperature can accelerate the gelation of T-Na nanocompound. In the T-Na gel, there exists a strong interaction between TCPP and NaMMT as the mass ratio is 1:5.5-5.7. T-Na nanocompound gel is capable of adsorbing large amounts of toluene. In the TPU/T-Na composites, NaMMT is a nano-dispersion material with intercalated and exfoliated state. According to the results by CONE, T-Na nanocompound flame retardant is more effective for TPU rather than relatively pure NaMMT and TCPP.