Compared to general public and residential buildings, large public buildings are often difficult to construct and have a long construction period, creating greater construction energy consumption and carbon emissions on the one hand, while generating a large amount and many types of difficult-to-track process data on the other. As such, it is difficult to measure carbon emissions and analyze various influencing factors. By realizing the simple calculation of energy consumption and carbon emissions, as well as discerning the degree of influence of various factors based on the results of influencing factors research, it is of considerable practical significance to propose energy savings and emission reductions in a targeted manner. In view of the above, this work aimed to establish a more practical calculation method to measure energy consumption and carbon emissions in the construction of large public buildings, as well as to identify the multiple influencing factors related to energy consumption and carbon emissions during the construction process. To demonstrate the practicality of our approach, quantitative calculations are carried out for a new terminal building in a certain place and from the perspective of sustainable urban construction; thus, the driving factors of the traditional STIRPAT model are extended to seven. Based on the calculation results, a modified STIRPAT model is used to analyze the comparative study of impact factors, such as population and construction machinery performance, on energy consumption and carbon emission intensity. The results show the following: (1) The energy consumption value per square meter of this terminal building is 3.43 kgce/m², and the average carbon emission per square meter is about 13.88 kgCO₂/m², which is much larger than the national average of 6.96 kgCO₂/m², and (2) the type of energy used in the construction process has the greatest degree of influence on energy consumption and carbon emission, and the local GDP, population factor, construction machinery performance specifications, and shift usage also show a positive correlation with the growth of total energy consumption and carbon emissions. Moreover, while the government’s continuous investment in energy conservation and environmental protection has reduced the total energy consumption and carbon emissions in construction, there is still considerable room for improvement. Finally, according to the results, we provide theoretical references and constructive suggestions for the low-carbon construction of large public buildings in the construction stage. Thus, the results of our study will allow policy makers to formulate appropriate policies.

Low-heat Portland cement and ground granulated blast furnace slag are widely used for the preparation of hydraulic concrete. Nevertheless, the effect and mechanism of corrosion on low-heat Portland cement paste mixed with ground granulated blast furnace slag need to be further explored. This paper investigated the impact of ground granulated blast furnace slag on the calcium leaching of low-heat Portland cement paste by evaluating its mass loss, porosity, leaching depth, compressive strength, and Vickers hardness, and comparing it with the leaching performance of ordinary Portland cement paste. Furthermore, the phase composition and morphology of low-heat Portland cement paste containing ground granulated blast furnace slag were analyzed by X-ray diffraction, mercury intrusion porosimetry, and scanning electron microscopy. The results indicate that, after 180 days of soaking in ammonium chloride solution, the mass loss rate, growth rate of porosity, leaching depth, and compressive strength loss rate of low-heat Portland cement paste were 8.0%, 43.6%, 9.1 mm, and 27.7%, respectively, while those of ordinary Portland cement paste were 7.4%, 37.8%, 8.4 mm, and 30.1%, indicating that low-heat Portland cement paste is slightly more damaging than ordinary Portland cement. The addition of ground granulated blast furnace slag could significantly improve the leaching resistance of low-heat Portland cement. For instance, after adding 20% ground granulated blast furnace slag, the above test values were 2.4%, 28.5%, 5.6 mm, and 20.8%, respectively. The reason for this is that ground granulated blast furnace slag has the potential to reduce the porosity of low-heat Portland cement paste, and it can also undergo the secondary hydration reaction with its hydration product Ca(OH)₂ to enhance the paste structure. Considering the cost performance, the suitable dosage of low-heat Portland cement paste for satisfactory leaching resistance is about 20%.

With the continuous improvement of building energy-conservation requirements, both traditional concrete external insulation and internal insulation have been unable to meet energy-saving needs. In order to meet the demands of building energy-saving in the new era, new precast concrete external-wall-insulation technology should be developed. In this study, a bending static test and numerical simulation were carried out to evaluate the influence of the thickness of inner concrete wythe and insulation and the length of plate-type shear connectors on the cracking condition, bearing capacity and composite degree of a precast ceramsite-concrete-insulated sandwich panel (PCCISP) under the outside-plane load. The results show that the failure modes of four precast ceramsite-concrete-insulated sandwich panels were all ductile failure of the concrete flexural members. The ultimate bearing capacity of the PCCISP decreased with the decrease in the thickness of the inner concrete wythe. Reducing the thickness of insulation had no significant influence on the ultimate bearing capacity. When the thickness of insulation was reduced by 30%, the composite degree of rigidity and bearing capacity of the PCCISP were increased by 8.85% and 2.67%, respectively. Increasing the length of the plate-type shear connector slightly increased the ultimate bearing capacity, but it had no obvious influence on the rigidity and bearing capacity composite degree.

To assist in addressing the problem where an aluminum alloy formwork (AAF) deforms more greatly under the action of lateral pressure and therefore does not meet the requirements of plaster-free engineering, we propose a method for determining the geometric parameters of this formwork based on a PSO algorithm and BP neural network with ABAQUS as the platform. The influence of six geometric parameters of the formwork on the maximum deflection value of the panel under the action of lateral pressure is studied using finite element analysis. The maximum deflection value of the panel is used as the index, and the influence of each factor is analyzed with an orthogonal test, and a set of optimal geometric parameters is obtained via extreme difference analysis and analysis of variance. The sample data are obtained via finite element simulation, and the PSO-BP neural network model is established using the six factors of the orthogonal test as input values and the maximum deflection of the panel as the output value, and the optimal geometric parameters are optimized using the PSO algorithm. The results indicate that the maximum deflection for the panel in the orthogonal scheme is 1.446 mm. The PSO-BP neural network prediction model demonstrates greater accuracy and a 31.74% reduction in running time compared to the BP neural network prediction model. The optimized PSO-BP neural network prediction model scheme reveals a maximum panel deflection of 1.296 mm, a 10.37% decrease compared to the orthogonal solution. These findings offer technical guidance and a foundation for optimizing AAF designs, presenting practical applications.

Hydraulic structures are frequently subjected to soft-water or acidic environments, necessitating serious consideration of the long-term effects of calcium leaching on the durability of concrete structures. Three types of common Portland cement (ordinary Portland cement, moderate-heat cement, and low-heat cement) paste samples widely applied to hydraulic concrete were immersed in a 6 mol/L NH₄Cl solution to simulate accelerated calcium leaching behavior. The mass loss, porosity, leaching depth, compressive strength, and Ca/Si ratio of the three types of pastes were measured at different immersion stages (0, 14, 28, 56, 91, 140, and 180 days). The Vickers hardness index was employed to compare cement samples subjected to erosion for 30 and 180 days. The microstructure and composition of the mineralogical phases of the leached samples were also determined by X-ray diffraction, thermogravimetric analysis, and scanning electronic microscopy. Accordingly, the time-varying behavior and deterioration mechanism of the different cements subjected to leaching were contrastively revealed. The results showed that the calcium leaching resistance of the low-heat cement was the best, followed by the moderate-heat cement and ordinary Portland cement, proving that the content and structure of Ca(OH)₂ and C-S-H gels were closely related to the leaching performance of the cement. The less Ca(OH)₂ and more aggregated C-H-S gels produced by C₂S led to better calcium leaching resistance in the cement. Therefore, the leaching performance of Portland cement could be effectively improved by reducing the content of C₃S and increasing the content of C₂S, and the dissolution rate of calcium ions under leaching could be reduced by controlling the low initial calcium content in cementitious materials. This paper offers theoretical guidance for mitigating the long-term effects of calcium leaching on hydraulic concrete structures by conducting a comprehensive comparative analysis of the damage behavior and deterioration mechanisms of various types of Portland cement under identical erosion conditions.

This paper presents a study on the mechanical properties of cement-stabilized steel-slag-based materials under freeze–thaw cycles for a highway project in Xinjiang. Using 3D scanning technology the specimen model conforming to the real steel slag shape was established. The objectives of the study are as follows: to explore the sensitivity between the macro- and micro-parameters of the specimen and to establish a non-linear regression equation; and to study the changes in mechanical properties of materials under freeze–thaw cycles, fatigue loading, and coupled freeze–thaw cycle–fatigue loading. The results show that there are three stages of compression damage of the specimen, namely, linear elasticity, peak plasticity, and post-peak decline. Maximum contact forces between cracks and particles occur mainly in the shear zone region within the specimen. The compression damage of the specimen is a mixed tensile–shear damage dominated by shear damage. When freeze–thaw cycles or fatigue loads are applied alone, the flexural strength and fatigue life of the specimens show a linear relationship of decline. The decrease in flexural modulus at low stress is divided into the following: a period of rapid decline, a relatively smooth period, and a period of fracture, with a tendency to change towards linear decay with increasing stress. In the case of freeze–thaw–fatigue coupling, the flexural modulus of the specimen decreases drastically by about 50% in the first 2 years, and then enters a period of steady decrease in flexural modulus in the 3rd–5th years.