Under corrosive environments, concrete material properties can deteriorate significantly, which can seriously affect structural safety. Therefore, it has important engineering applications to improve the durability performance at a lower economic cost. This paper proposes a new, highly durable concrete using inexpensive construction materials such as basalt fiber, sodium methyl silicate, and inorganic aluminum salt waterproofing agent. With the massive application of sewage treatment projects, the problem of concrete durability degradation is becoming more and more serious. In this paper, five types of concrete are developed for the sewage environment, and the apparent morphology and fine structure of the specimens after corrosion in sewage were analyzed. The density, water absorption, and compressive strength were measured to investigate the deterioration pattern of concrete properties. It was found that ordinary concrete was subject to significant corrosion, generating large deposits of algae on the surface and accompanied by sanding. The new concrete showed superior corrosion resistance compared to conventional concrete. Among other factors, the inorganic aluminum salt waterproofing agent effect was the most prominent. The study found that the strength of ordinary concrete decreased by about 15% in the test environment, while the new concrete had a slight increase. Comprehensive evaluation showed that the combination of basalt fiber and inorganic aluminum salt waterproofing agent had the best effect. Its use is recommended.

Thin-walled steel pipe concrete has better economic performance, but the problem of local buckling is more prominent with a thin-walled steel pipe; meanwhile, thin-walled steel pipe is more sensitive to the environment and the influence of rusting is more prominent. To solve the above problems, this paper proposes new spiral stiffened rib thin-walled steel pipe concrete laminated members to obtain better force and economic performance. Based on axial compression tests on five forms of composite members, this paper studies the nonlinear behavior of the axial compression of this new type of laminated member and the factors influencing it. The following conclusions are obtained. Under the constraint of the spiral ribs, the new composite member has good integrity and each part can ensure cooperative stress; the buckling of the steel pipe is well limited and the mechanical performance is significantly improved. Compared with ordinary thin-walled concrete-filled steel tubular members, the bearing capacity is increased by about 20% and the deformation ability is increased by more than 30%. The nonlinear behavior of the member in compression can be better achieved through finite element analysis. The parametric analysis shows that the pitch and the steel tube width-to-thickness ratio greatly influence the force behavior of the member. In contrast, the spiral rib width-to-thickness ratio and the external reinforcement only need to meet the structural requirements. Finally, based on the superposition theory, the proposed method of calculating the member’s axial compressive load-bearing capacity is given and design suggestions are made. The results of this paper can provide some basis for the engineering application of this new combination member.

The installation of grouted connections in deep-water offshore wind turbine jackets faces severe visibility constraints and limited diver operation time, necessitating an unmanned, real-time monitoring solution using remotely operated vehicles (ROVs). However, the lack of dedicated datasets and the challenge of balancing segmentation accuracy with edge-deployment efficiency remain major obstacles. This paper addresses these gaps by constructing, to the best of our knowledge, the first underwater grout overflow instance segmentation dataset reported in the published literature, comprising 2088 images and 5733 polygon instances annotated under a two-level semantic system (“overflow” and “overflow warning”). On this basis, we propose a collaborative optimization method based on YOLOv11n-seg and validate it with a strict 12-fold leave-one-group-out cross-validation (LOGOCV; 2088 images, video-level disjoint groups, unweighted macro averages). We first design a lightweight Multi-Path Feature Extractor (MPFE), MPFE-lite, retaining only the B3 asymmetric strip-convolution branch (depthwise 1 × 5 and 5 × 1 kernels). MPFE-lite improves mask mAP@0.5 over the YOLOv11n-seg baseline by 3.85 percentage points (35.9% → 39.8%; paired t-test p = 0.017, Wilcoxon p = 0.027, 10 wins out of 12 folds) while using 11.6% fewer parameters (2.54 M vs. 2.88 M) and slightly fewer GFLOPs (9.80 vs. 9.90). The full three-branch MPFE is also significantly better than baseline (mask mAP@0.5 +3.53 points, p = 0.007/0.002), but adding its dilated multi-scale and fixed Sobel branches to B3 gives no significant cross-group gain; the Dual-Branch Channel-Spatial Attention (DCSA) attention module and DySample upsampling, which appeared beneficial on a single fixed split, likewise produce no significant LOGOCV improvement and are therefore removed. For deployment-oriented compression, a Bidirectional Feature Pyramid Network (BiFPN)-based variant (1.21 M parameters, 7.38 GFLOPs) offers a 58.0% parameter reduction at a cost of 3.10 mask-mAP points, providing an optional lightweight configuration. Against peer lightweight models over an eight-fold partial comparison, MPFE-lite is significantly more accurate than YOLOv5n-seg and YOLOv6s-seg and comparable to YOLOv8n-seg while being lighter. Gradient-weighted Class Activation Mapping (Grad-CAM) visualizations provide qualitative supporting evidence consistent with the strip-convolution design rather than definitive confirmation of its mechanism. This work provides a complete engineering closed-loop from model inference to on-site visualization, filling critical data and algorithmic gaps in underwater grout monitoring.