Salt crystallization erosion significantly undermine the integrity of masonry structures in coastal regions, necessitating an in-depth understanding of its impact on seismic performance. In this paper, a comprehensive analysis of the seismic response of confined masonry walls affected by crystallization damage has been presented, and different seismic performance indexes, such as damage propagation, hysteresis properties, and energy dissipation, have been evaluated. The study primarily focuses on the impacts of chloride salt corrosion cycles (CSCs) and the number of constructional columns. As the number of CSCs increased, the confined brick masonry specimens showed a decline in load-carrying, deformation, and energy dissipation capacities. The wall with more constructional columns exhibited better performance and a fuller hysteretic curve. Notably, the single-wall specimen CBMS-4 exhibited a significant decline in mechanical properties compared to CBMS-1, with reductions of 25 % in cracking load, 21 % in peak load, and 51 % in total energy consumption. Likewise, the double-wall specimen CBMD-4 showed degraded performance, with reductions of 20 % in cracking load, 16 % in peak load, and 35 % in total energy consumption compared to CBMD-1. Based on the experimental results and the modified I-K model, a restoring force model for confined masonry walls subjected to chloride salt crystallization was proposed. Also, a relation was proposed for computing the skeleton curve of confined masonry walls, considering the impact of chloride salt corrosion damage and axial load ratio. Hysteresis laws were also introduced to quantitatively describe the reduction in fundamental mechanical properties, including basic strength, post-peak strength, as well as unloaded and reloaded stiffness. The calculation results from the restoring force model for confined masonry walls were found to be consistent with the experimental results, corroborating its effectiveness in describing the mechanical and hysteretic characteristics of the confined masonry wall. Hence, the proposed model is suitable for the elastoplastic analysis of masonry structures in coastal areas. © 2025

通过对经历不同冻融循环次数（N=0、25、50、75、100、125、150）的再生混凝土立方体试块进行单轴受压试验,研究了冻融循环次数对再生混凝土应力应变全曲线的的影响,揭示了冻融循环次数对再生混凝土峰值应力、峰值应变和弹性模量的影响规律。试验结果表明,随着冻融循环次数的增加,再生混凝土峰值应力和弹性模量呈现减小趋势,峰值应变逐渐增大,应力-应变曲线趋于扁平。在此基础上建立了考虑冻融循环次数的再生混凝土单轴受压本构模型及参数的数学表达式,特征参数呈现出明显的规律性变化,试验结果对再生混凝土的应用和研究有一定参考价值。

胶凝砂砾石（CSG）是一种低强度、低弹性模量的新型筑坝材料。为改善CSG材料的力学性能,选取天然砂砾石为原材料,以不同掺量的硅灰（S=0,2%,5%,8%,10%,12%）替代水泥配制了6批试件,通过CSG试件单轴压缩试验研究硅灰掺量对CSG材料力学性能的影响。结果表明:硅灰掺量对CSG宏观应力-应变行为影响显著,随着硅灰掺量的提高,抗压强度、弹性模量呈增大趋势,峰值应变则先减小后增大。通过建立考虑硅灰掺量的本构模型,分析了统计损伤模型中5个特征参数的变化规律,拟合得到了5个参数随硅灰掺量的表达式,进而研究硅灰掺量对胶凝砂砾石损伤演化机制的影响。

通过机械粉磨对黄河泥沙进行活性激发，研究了随机械粉磨时间的增加，泥沙颗粒群特性和胶凝活性变化，从颗粒群粒径分布变化、矿物组成、晶体结构等方面表征了其性能的变化且阐释了活化机理，并利用灰色关联度分析定量化表征颗粒粒径分布的变化与活性指数的内在联系。活性指数随着机械粉磨时间的增加先增加后减小，其中机械粉磨40 min时，泥沙活性指数最高，3 d、7 d、28 d分别为53.9%、67.6%、84.7%。在机械粉磨40 min内，颗粒粒径变化幅度较高，超过40 min后粒径变化幅度较小。泥沙粒径分布中，小于20 μm的颗粒对活性指数起增强作用；大于20 μm的颗粒对活性指数起劣化作用；10-20 μm粒径范围内颗粒含量的波动对活性指数的影响最大。经机械粉磨后，泥沙矿物晶体的衍射峰半高宽增大，晶粒尺寸减小，晶体的结晶度显著下降，这些晶体结构参数的变化是泥沙活性指数提高的内在因素。

考虑钢纤维高强混凝土试件细观非均质性对宏观断裂的影响机制,将钢纤维掺量、长度、直径及钢纤维抗拉强度等细观层面的钢纤维特征参数,引入钢纤维高强混凝土宏观断裂模型的虚拟裂缝扩展量的具体计算公式,从而发展了考虑钢纤维特性的可

In this paper, the bending performance of a MSFRHPC (containing steel fiber, polyvinyl alcohol (PVA) fiber, and CW)-reinforced beam was studied for the first time. Introducing a multiscale fiber system increased the first crack load (up to 150%), yield load (up to 50%), and peak load (up to 15%) of reinforced beams. The multiscale fiber system delays cracking of the reinforced beam, reduces crack width of the reinforced beam in normal use, and improves the durability of the beam. Considering yield load and peak load, the reinforcing effect of multiscale fiber on the high-reinforcement ratio beam (1.00%) is better than that on the low-reinforcement ratio beam (0.57%). Introducing fibers slowed the development of cracks in the reinforced beam under bending. With the added hybrid fiber, the deformation concentration of reinforced beams after yield was more significant with concentration in 1 or 2 cracks. A model for predicting the flexural capacity of MSFRHPC-reinforced beams was proposed, considering the action of multiscale hybrid fibers. This research is helpful for structure application of MSFRHPC-containing CW. © 2023 Techno-Press, Ltd.

为研究酸雨环境下水泥砂浆、混合砂浆、粉煤灰砂浆、砖块的力学性能变化，采用人工气候环境模拟实验室对砂浆试块及砖块进行加速腐蚀试验。在酸雨腐蚀0、50、100、150、200、250、300次的变量下，研究水泥砂浆试块、混合砂浆试块、粉煤灰砂浆试块、砖块的表观特性、力学性能及腐蚀机理。结果表明：随着酸雨腐蚀循环次数的增加，砂浆试块及砖块的表观形态变化明显；砂浆试块的抗压强度呈先增加后降低的趋势。与水泥砂浆相比，混合砂浆试块的耐酸雨腐蚀性能最差；掺入粉煤灰后砂浆的抗酸雨侵蚀能力没有明显改善。建立了酸雨侵蚀后砂浆试块、砖块抗压强度衰变规律的数学模型。

This study presents a simple model for determining the fracture parameters of dam concrete, by introducing the Fuller and Thompson formula for estimating the average aggregate size d(av) when only the maximum aggregate size d(max) is known. The crack propagation mechanism of dam concrete is analyzed at the mesoscopic level. The calculation method of fictitious crack growth length Delta afic$$ \Delta {a}_{\mathrm{fic}} $$ and characteristic crack length a infinity*$$ {a}_{\infty}<^>{\ast } $$ of dam concrete is also described. A normally distributed fracture model for the variation of fracture toughness K-IC and tensile strength f(t) with d(av) is proposed for different specimen patterns (wedge splitting, compact tension, and three-point bending) and different relative sizes. The fracture parameters derived by this model show consistent with the results obtained in the laboratory. The fracture failure curve of a dam concrete is established, and the peak state of a true structure of large size is also predicted satisfying linear elastic fracture.

The wastewater from ready-mixed concrete plants is currently being recycled as concrete mixing water. It has attracted significant attention from the construction industry and researchers since it promotes sustainable development through environmental protection, energy-saving, and emissions reduction. This article review first introduces the nature of wastewater in ready-mixed concrete plants in different regions. Then the effects of solid content in water on various properties of concrete, including working performance, durability and microscopic properties, are reviewed, respectively, when concrete is mixed with wastewater instead of tap water. Furthermore, the microscopic mechanism of action in concrete mixing with wastewater is discussed, and future work is recommended. This review provides fundamentals on the study of the properties of concrete after wastewater is mixed into concrete.