Coatings

The use of high-strength reinforcing steel is an effective way to improve the flexural efficiency of reinforced concrete beams. However, the flexural behaviour of beams reinforced with 630 MPa grade longitudinal rebars in combination with normal-strength concrete is still not fully understood, especially with regard to serviceability performance. In this study, the flexural performance of simply supported RC beams reinforced with HRB500, HRB600 and HRB630 longitudinal rebars and cast with C60 steel-fibre-reinforced concrete was investigated through a combined experimental and numerical approach. Six beams were tested under four-point bending to examine cracking patterns, deflection development and ultimate flexural capacity. A three-dimensional nonlinear finite element model based on the Concrete Damage Plasticity model in ABAQUS was then established and calibrated against the test data. Using the validated numerical model, a parametric study was carried out to investigate the influence of steel grade, tensile reinforcement ratio on flexural stiffness and ductility. Test results indicate that, for the same reinforcement ratio, the ultimate moment capacity of HRB630 beams is about 8% higher than that of HRB600 beams and about 25% higher than that of HRB500 beams, while a ductile flexural failure mode governed by yielding of tension reinforcement is still maintained. The study also shows that for HRB630 beams, deflection predictions need to account for the higher steel stress level and the deterioration of tension stiffening effects. In general, the results demonstrate that HRB630 high-strength rebars can be safely and efficiently used in flexural members when the tensile reinforcement ratio is kept within the under-reinforced range and steel-fibre-reinforced concrete is adopted to improve cracking and deflection performance.

Crust Ash Triad Clay (CATC) is a traditional construction material commonly used for jointing coastal stone masonry in Southeast China. Its surface is prone to blackening in coastal environments. This study focused on traditional stone masonry residences within the protection area of Quanzhou Shihu Ancient Wharf. A systematic detection and analysis were conducted using combined technologies: XRD, Raman, SEM-EDS, and 16S rRNA sequencing. The results revealed that the CATC substrate is mainly composed of quartz and feldspar minerals, with calcite and other substances as binding components. The black coating on the surface is a loose material attached to the substrate, retaining some of the original minerals. The core mechanism of blackening lies in the coastal environment’s abundance of salt spray and humidity. The sulfate substances carried by rainwater react synergistically with metal ions such as Cu, Fe, and Mn in the substrate under the metabolic action of anaerobic bacteria, producing metal sulfide minerals. Photoautotrophic bacteria generate oxygen through photosynthesis, promoting the oxidation and acidification of metal sulfide. This process directly triggers the chain deterioration of the CATC substrate. Based on the principle of “minimal intervention”, physical waterproofing or laser stain removal can be implemented. This study provides scientific support for optimizing the durability and achieving precise protection of traditional building materials in coastal stone structure heritage.

The aim of this review is to explore the improvement in diffraction efficiency, photosensitivity and pressure sensitivity in holographic materials containing glycerol. Glycerol is a well-known, non-toxic, water-soluble polyol compound. Glycerol polymers have attracted increased attention recently due to the diversity of the available compositions. Glycerol provides access to a range of monomers for subsequent polymerizations. Various glycerol containing polymers, including polyvinyl alcohol films, polyesters, polyethers and polycarbonates, have been investigated for different applications. It was discovered in 2009 that the addition of glycerol to the composition of water-soluble holographic photopolymers facilitates the faster formation of holograms due to greater photosensitivity. It was also discovered that the presence of glycerol in holographic photopolymers makes them highly pressure-sensitive. A new family of holographic photopolymer materials, containing glycerol and capable of recording holograms with bright reflections, was reported. The novel photopolymers are composed of glycerol, a polymeric binder, a crosslinking monomer, an initiation system, and sensitising dyes. No wet-processing of holograms is necessary. Each holographic photopolymer film contains bis-acrylamide (BA) monomer in polyvinyl alcohol matrix, triethanolamine and methylene blue dye solution, glycerol and water. It was shown that the new holographic material is capable of reaching a refractive index modulation matching that of the well-known acrylamide photopolymer material, but more quickly. The new holographic photopolymer materials are cheap and environmentally friendly. The use of glycerol to improve diffraction efficiency, photosensitivity and pressure sensitivity in holographic recording layers continues to expand. This review describes the development and applications of glycerol-containing photopolymer materials. An environmentally friendly diacetone-based photopolymer was developed. The positive effect of glycerol on N-vinylpyrrolidone photopolymer was investigated. Finally, potential opportunities for future research in the area of glycerol-containing photopolymers are outlined.