In the field of construction, the promotion of prefabricated buildings has been strongly supported by the state due to its low-carbon, environmental protection and high-efficiency characteristics. The process of design, prefabrication, and installation, is restricted by factors such as unsound policy standards, insufficient technological innovation, lack of professional talents, and high costs, which have led to the slow development of prefabricated buildings in China. The main factors that restrict the development of prefabricated buildings in Yancheng are identified from the researcher’s point of view by literature review and questionnaire survey method. The degree of centrality and cause of each constraint has been analyzed by the decision-making laboratory method (DEMATEL), and the interpretation structure method (ISM) was used to build a multi-level hierarchical structure model of constraints, the logical relationship, hierarchical relationship and relative importance of each constraint are clarified. It is concluded that industry policies, imperfect standards and insufficient government publicity are the fundamental reasons to hinder the development of prefabricated buildings in Yancheng. According to the order of the centrality, the main restrictive factors are determined, which benefits the establishment of the homologous counterplan for the vigorous promotion of prefabricated buildings in Yancheng.

Waste fly ash (WFA) and secondary aluminum dross (SAD) are common solid wastes inducing environmental pollution. These materials contain certain active substances that can be used in cement-based materials. Therefore, cement concrete can be used to solidify these solid wastes. In this study, the influence of the assembly unit of secondary aluminum dross (SAD) and waste fly ash (WFA) on the properties of ultra-high-performance concrete (UHPC) is investigated. The slump flow, the plastic viscosity, the yield shear stress, and the initial setting time of fresh UHPC are measured. Moreover, the flexural and compressive strengths and the dry shrinkage rate (DSR) are determined. The electrical resistance and reactance are tested. The electron microscopy spectroscopy (EDS), thermogravimetric analysis (TG), and X-ray diffraction spectrum (XRD) curves are obtained for revealing the mechanism of macroscopic performances. Results show that due to the optimal specific surface area and the volcanic ash effect, the UHPC with the assembly unit of 50% SAD and 50% WFA provides the highest slump flow, DSR, and mechanical strengths, while the corresponding plastic viscosity, yield shear stress, and electrical resistance are the lowest. The SAD can delay the setting time of UHPC. The relationship between the electrical resistance or the electrical reactance and the mass ratio of SAD accords with the quadratic function. The corresponding electrical resistance is the lowest. The relationship between the mechanical strengths and the electrical resistance fits with the cubic function. The leaching amounts of Z_n and C_r increase in the form of cubic function with the immersing time. Meanwhile, the SAD can decrease the Z_n and C_r by 0%–46.3% and 0%–45.2% respectively. As obtained from the EDS results, the element of Al is increased by adding SAD. The XRD curves show that the crystals of Al₂O₃ are increased and the SiO₂ crystals are decreased by the added SAD. UHPC with 50% SAD exhibits the highest compact microstructures and the least Ca(OH)₂ and 3CaO·S_iO₂ hydration products. The TG results show that UHPC with 50% SAD shows the lowest TG values of all the groups. This research will provide new UHPC materials and techniques applied in solidifying the WFA and SAD in the future.

Magnesium oxysulfate (MOS), mainly composed of magnesium oxide and magnesium sulfate, is a kind of gas-hardening cementing material with low energy consumption and CO₂ emissions. In order to develop environment-friendly cement-based materials, MOS needs to be studied systematically. The paper mainly investigates the influence of citric acid (a retarder) on the working and mechanical properties of MOS paste. In this study, the setting time of fresh MOS paste is determined. The flexural and compressive strengths of hardened specimens exposed to the environment of water dry-wet (D-W) alternations, freeze-thaw (F-T) cycles, and sulfate D-W alternations are investigated. Furthermore, the drying shrinkage (D-S) rate of MOS paste is tested for 3 days and 28 days. The specimens are cured in standard or CO₂ curing environments. A scanning electron microscope energy spectrum (SEM-EDS) is obtained to analyze the morphology of hydration products. Results show that citric acid can increase the setting time of MOS paste. The citric acid and CO₂ curing have a positive effect on the mechanical strengths and the resistance to erosion by water, F-T cycles, and sulfate D-W alternations. The D-S rate decreased in relation to the increasing dosages of citric acid and increased with CO₂ curing. MOS with 0.3% of the total binder material mass shows the best erosion resistance. As observed in the results of SEM-EDS, the CO₂ curing and the citric acid can make the hydration products denser.

Secondary aluminum dross containing a large amount of active substance can be used to prepare concrete. The mechanical strengths, the mass loss rate (MR) and the relative dynamic modulus of elasticity (RME) of ultra-high-performance concrete with secondary aluminum dross are researched. The NaCl freeze–thaw cycles (F-Cs) and dry–wet alternation (D-A) effects with NaCl and Na₂SO₄ are considered. The corresponding permeability of chloride ions and the carbonation depth (D_c) are obtained. The scanning electron microscope (SEM) photos are researched to reveal the variation of the mechanical mechanism. Results show that after specimens’ suffering from the action of 20 NaCl D-As, the MR of ultra-high-performance concrete is the highest. Specimens exposed to 200 NaCl F-Cs show the lowest MR and CMC. The RME of UHPC under salt actions increase in the order of 20 NaCl D-As < 20 Na₂SO₄ D-As < 200 NaCl F-Cs. After suffering 200 NaCl F-Cs, 20 Na₂SO₄ D-As and 20 NaCl D-As, the corresponding D_c values are 1.86 mm to 2.31 mm, 1.79 mm to 2.23 mm and 2.11 mm to 2.76 mm. The flexural strength decreases at the rates of 0.99%–25%, 3.92%–27.84% and 1.47%–21.59% respectively. The MR increases and the RME decreases as the cubic function changes with the amount of salt erosion. After the secondary aluminum dross is added, the CMC decreases at the rates of 0% to 11.53%, 0% to 33.17% and 0% to 8.41% during the process of the salt action. The SAD can reduce the D_c with the decreasing rates of 19.48%, 23.55% and 19.73%. The SAD can increase the compactness of ultra-high-performance concrete. Ultra-high-performance concrete suffering from 20 NaCl D-As shows the largest number and the highest width of cracks. However, when the specimens are exposed to 20 Na₂SO₄ D-As, the number of cracks is the lowest and the width is the narrowest.

In this study, the influence of CO₂ curing on the corrosion resistance of reinforced alkali-activated compounds is investigated. Fly ash (FA) and blast furnace slag powder (BFS) are used as mineral admixtures. The specimens were subjected to dry–wet alternations with 3% NaCl, used to simulate a concrete structure under a corrosion environment. The ultrasonic velocity, mass loss rate, and electrical characteristics (such as electrical resistance, AC impedance spectra, and corrosion area rates determined by Tafel curves) are utilized to determine the degree of corrosion. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) are used to analyze the corrosion mechanism. Results show that the corrosion resistance is decreased by the addition of FA but improved by CO₂ curing. When CO₂ curing is provided, the addition of BFS shows a higher enhancing effect on the corrosion resistance than that of FA. The equivalent circuit diagram of reinforced alkali-activated compound mineral admixtures obtained by AC impedance spectra is composed of three electrical elements (electrical resistance and capacitance in parallel) in series. The X-ray diffraction results show that adding BFS and CO₂ curing can decrease the rust’s iron oxides on the steel bars’ surface. Finally, as found in the SEM photos, BFS and CO₂ curing can effectively improve the compactness of specimens. Meanwhile, the roughness of hydration is increased by CO₂ curing.

In order to improve the innovation capabilities of Yancheng’s prefabricated construction industry, the Dawei Innojoy patent database was used to search the prefabricated construction technology patent literature data of Yancheng and other major cities in the Yangtze River Delta region from 2012 to 2022, and the prefabricated construction patents in Yancheng were analyzed from the number of patent applications. Analysis and research were conducted on trends, application type composition, applicants, technical fields, patent legal status, etc. At the same time, the prefabricated building technology innovation capability evaluation system was constructed, and the factor analysis method was used to compare and analyze the prefabricated building technology patent indicators of Yancheng and major cities in the Yangtze River Delta region. The results show that Yancheng has a small number of patent applications, a small proportion of invention patents, a low patent authorization rate, and a low patent conversion rate, and the industry-university-research chain needs to be opened up. Among the cities in the Yangtze River Delta, Yancheng’s comprehensive innovation ability in prefabricated building technology is medium to low, where it lags behind in terms of the scale and quality of technological innovation and ranks at the forefront of technological innovation operations. Based on this, the article puts forward countermeasures and suggestions for Yancheng’s prefabricated building technology patent applications from three levels, macro, meso, and micro, in order to achieve efficient innovation and promote the high-quality development of Yancheng’s new building industrialization.