To improve the mechanical properties of conventional sticky rice-lime mortar, high strength pregelatinized sticky rice-lime mortar (HPR-LM) was modified with a pregelatinized sticky rice via accelerated carbonation. The effects of mass fraction of pregelatinized sticky rice and water-solid ratio on the carbonation properties of HPR-LM were investigated. The results show that the maximum carbonation reaction degree of HPR-LM with sufficient water and larger porosity can be obtained at a water-solid ratio of 0.3. The change of conductivity and pH value of saturated Ca(OH)₂ solution slows down, and the temperature increase of HPR-LM reduces due to the action of pregelatinized sticky rice, thus retarding the carbonation of HPR-LM. CaCO₃ precipitation forms fusiform calcite on the template of molecular chain of pregelatinized sticky rice. The compressive strength of HPR-LM with 3% pregelatinized sticky rice is 56.8% higher than that of pure lime mortar, and calcite grain reaches the minimum size and the density of HPR-LM becomes the maximum value.

Pyrolusite is widely used as desulfurization materials for sulfide-containing wastewater, sulfide-containing waste gas, biogas and process gas. However, some studies on the characteristics and applications of its desulfurization products still are lack. This paper simulated the conditions of wastewater desulfurization, normal temperature waste gas desulfurization and high-temperature desulfurization of process gas to obtain the corresponding pyrolusite sulfide products, and investigated the phase composition of sulfureted pyrolusite in different ways and the effect of cadmium removal from wastewater and its mechanism. The effects of solution pH value, initial cadmium concentration, reaction time and temperature on the cadmium removal efficiency were investigated. The samples before and after cadmium removal of sulfureted pyrolusite in different ways were characterized by X-ray powder diffraction and scanning electron microscopy. The results show that the cadmium removal capacity of the products obtained under the conditions of wastewater desulfurization, normal temperature waste gas desulfurization and process gas high-temperature desulfurization are 73.93, 66.76 mg/g and 44.96 mg/g, respectively. The mechanism of removing cadmium from desulfurization products is the dissolution precipitation reaction between MnS and CdS due to the solubility product difference. The difference of crystal structure, morphology and crystallinity of MnS formed by different sulfuration methods is a main reason for its different cadmium removal effect. Pyrolusite desulfurization products have a good removal effect on heavy metal cadmium ions, which can have promising application prospects in environmental pollution control.

Interfacial transition zone (ITZ) between cement matrix and aggregate is regarded as a weak phase that affects the mechanical properties and durability performance of concrete. Therefore, resolving ITZ around aggregate has always attracted great attentions in concrete research. Due to the limitation of resolution, using industrial X-ray computed tomography (XCT) to address three-dimensional (3D) morphology of ITZ becomes a challenge. However, the extremely high X-ray attenuation of mercury can greatly increase the contrast of XCT images when the pores of ITZ are filled with mercury. This regime allows visual characterization of ITZ for cement-based materials after mercury intrusion porosimetery (MIP). A glass rod was used as an aggregate to fabricate connected matrix-aggregate ITZs. The results show that the residual mercury droplets in pores after MIP enhance the gray values of ITZ, thus addressing the 3D structure of ITZ. The findings provide a new path to exploring the pore structure of matrix-aggregate ITZ in cement-based materials.

Carbon fiber based electrodes were prepared by a solvent exchange method with natural cellulose fibers as versatile supports of lignin nanoparticles (LNPs) to uniformly in-situ load LNPs on the surface of fibers. The morphology, specific surface area, thermal stability, phase composition, structure and electrochemical performance of carbon fiber electrodes were investigated by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, thermogravimetric analysis, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and electrochemical tests, respectively. The results show that the prepared carbon fiber based electrode has a maximum specific capacitance of 7.88 F/g at an initial mass ratio of LNPs to cellulose fiber of 1∶10, which is greater than that of the control biomass carbon fiber (0.60 F/g) without loading LNPs. After 10 000-cycle test (10 A/g), the capacitance retention is still 93%. Also, LNPs loaded on the surface of fibers can effectively endow composite carbon fiber electrodes with a high specific surface area and a high carbon content, which can provides a possible path for the effective utilization of lignin in energy fields.

Large size ordered structure AgO electrode materials were prepared by an electrochemical method. The crystal structure, phase composition, microstructure, formation mechanism and discharge properties of samples were investigated. The results of crystal structure and phase composition show that AgO material synthesized has a strong (002) orientation and a relatively high purity phase. The results of microstructure indicate that AgO material has an ordered columnar arrangement structure with a straight-through hollow structure and a column diameter of 1-3 μm, which is conducive to the electrolyte diffusion. Based on the results of thermal analysis, the purity of AgO material is higher than 98.5%. Under the action of electric field force and gas evolution, AgO material forms an ordered columnar structure through self-assembly, which is conducive to the diffusion of electrolyte solution in the electrode and greatly improves the discharge performance of the large size AgO electrode. The average voltage of AgO electrode is 1.67 V and the electrochemical utilization ratio is 75.6% when the discharge current density is 770 mA/cm² and the cut-off voltage is 1.5 V, enhancing the high-rate discharge performance and utilization. Realizing a small-batch preparation of large-size AgO electrode material can meet the requirement of industrial production and application.

The Great Wall is one of the greatest construction projects in the history of human civilization, and the traditional lime mortar is an important guarantee standing for centuries without falling. Exploring the phase and composition ratio of ancient mortar used in the Great Wall through modern scientific and technological means and analyzing its performance evolution process, we could effectively understand the characterizations of traditional technology. The use of the past for the present is of great significance in guiding and promoting the conservation and restoration of endangered ancient buildings. Therefore, four representative locations were selected in the Dazhuangke of the Great Wall. The physical properties, phase composition and ratios of the ancient mortar samples were systematically analyzed by X-ray fluorescence spectroscopy, X-ray diffractometry, thermogravimetric-differential thermal analysis, Fourier transform infrared spectroscopy, iodine-starch test, mercury-pressure test and scanning electron microscopy, respectively. The comparison with the modern repair mortar reveals the evolution pattern of the performance of ancient mortar. The results show that the ancient mortar is a pure air-hardened lime mortar. The type of lime is a magnesian lime. No water-hardening components occur in the mortar, and no aggregate components or organic additives appear. The long-term carbonation process can inhibit the crystallinity of calcite crystalline calcium carbonate, refine the granularity of calcium carbonate, and effectively improve the denseness of the mortar hardening body. This could be one of major reasons for the superior performance of ancient mortar.

To study the brittleness index change of basalt fiber reinforced concrete (BFRC) and input energy, elastic energy and dissipative energy evolution law under cyclic loading at different confining pressures, triaxial compression tests and cyclic loading tests at different confining pressures (i.e. 5, 10, 15, 20 and 30 MPa) were carried out in a model MTS816 Rock Test System, and the energy drop coefficient was introduced to express the BFRC brittleness index. The results of triaxial compression test show that except 5 MPa, the drop coefficient of BFRC at other confining pressures is increased by 1.26, 2.03, 2.77 and 4.24 times, respectively. Based on the results of cyclic loading test results, when the cycle is controlled by displacement, the unloading point at the post-peak stage can be obtained according to the set displacement value instead of the peak stress point of a single cycle. The energy evolution curve of BFRC has obvious stage characteristics, and the energy value of a single cycle is closely related to the loading and unloading points. The stable state of BFRC can be indirectly judged by a ratio of elastic energy to dissipative energy.

Nano-sized calcium silicate hydrate (CSH) is an efficient nucleating agent for Portland cement, which can improve the early strength. In this paper, CSH/citric acid nanocomposites were prepared via nucleation and growth isolation with citric acid as a dispersion stabilizer at different citric acid concentrations. Effect of citric acid dosage on the structure and particle size distribution of CSH/citric acid nanocomposites (nano-CCNs) as well as the properties of Portland cement was investigated. The results show that citric acid can intercalate on the CSH, and the average particle size of nano-CCNs is between 90-160 nm. The higher the content of citric acid in nano-CCNs, the smaller the particle size and the more citric acid released in the alkaline solution at pH=13. Nano-CCNs accelerates the cement hydration, modifies the pore structure and increases the compressive strength of the cement (12 h, 1 d, 3 d, 7 d, 28 d) due to the synergy between the nanocrystal nucleus and citric acid released from the CCNs.

The shear strength index values (cohesion and internal friction angle) are important data for the study of constitutive relationships and numerical simulation analysis of ultra-high performance concrete, which are crucial to revealing the reinforcement and toughening mechanism of steel fibers in ultra-high-performance concrete. The axial direction and radial direction stress-strain full curves data and stress circles of ultra-high performance concrete under each stress path were obtained via conventional triaxial compression experiment of ultra-high performance concrete with different steel fiber volume contents (i.e., 0%, 1%, 2% and 3%) at different confining pressures (i.e., 0, 10, 20, 40 MPa and 60 MPa). Based on the stress-strain full curve, the ultra-high performance concretes with different steel fiber contents have some rheumatic properties in the triaxial compression process, and the deformation properties and destruction modes change from brittleness to plasticity at a confining pressure of 40 MPa. The specific values of internal friction angle (φ) and adhesion (c) at different confining pressures of each steel fiber content ultra-high performance concrete were deduced from the stress circle data, and the changes of φ and c with the increase of steel fiber content and confining pressure were also analyzed. The results show that the cohesion increases with the increase of confining pressure, and the internal friction angle decreases with the increase of confining pressure at the same steel fiber content. The maximum cohesion and the minimum internal friction angle are achieved at the same confining pressure and a steel fiber volume content of 2%. The content of steel fiber has little effect on the internal friction angle at a certain confining pressure.

The failure mechanism of fly ash ceramsite lightweight aggregate concrete under triaxial compression was investigated via conventional triaxial tests at different strength grades and lateral confining pressures. The failure morphology and stress-strain curve of fly ash ceramsite concrete specimens under triaxial compression were analyzed, and the failure mechanism was revealed. The results show that under triaxial compression, the fly ash ceramsite concrete has three failure phenomena as the applied confining pressure increases, i.e., vertical splitting failure, oblique shear failure, and no obvious cracks. There exists a platform flow plastic phenomenon in the full strain curve with the increase of confining pressure. The triaxial compression of fly ash ceramsite concrete can be properly described by an established general formula for the Mohr-Coulomb, octahedral shear stress failure criterion and the Rendulic plane failure criterion.