Advances in coral aggregate concrete and its combination with FRP: A state-of-the-art review

As an economical and eco-friendly construction material, coral aggregate concrete (CAC) plays an increasingly important role in emerging marine engineering applications. CAC fully utilizes local raw materials on remote islands. Due to the porous structure and low-strength characteristics of coral aggregates, CAC exhibits unique characteristics compared to ordinary concrete. This paper presents a state-of-the-art review of the properties of CAC, including (1) the physical properties of coral aggregates; (2) the mechanical properties of CAC under uniaxial and multiaxial compression; and (3) the durability of CAC especially its chloride ion resistance and performance under drying-wetting cycles. To overcome the challenges of steel corrosion in marine environments, fiber-reinforced polymer (FRP) has been indicated to be a promising material for applications in CAC construction. The latest studies on the combination of FRP and CAC are reviewed, including the use of FRP tubes and bars.

Mechanical properties of recycled aggregate concrete under multiaxial compression

The mechanical properties of recycled aggregate concrete under multiaxial compression were tested by servo-controlled setup (TAWZ-5000/3000). Properties of strength and stress–strain relation were obtained, and the influence factors of stress ratio and recycled coarse aggregate replacement ratio were analyzed. The results show that the strength of recycled aggregate concrete under multiaxial compression is higher than that of under uniaxial state, the stress ratio and recycled coarse aggregate replacement ratio have obvious effect on strength, and the shape of stress–strain curve is also varied with different levels of the two factors. Failure criterion can reflect the strength relation for recycled concrete under multiaxial stress state. Kupfer’s failure criterion is selected to describe strength properties under biaxial stress state, and the failure envelope reflects the energy absorption of different mix series. Based on octahedral stress theory, the tensile and compressive meridians have been proposed to analyze the strength characteristics under triaxial compression, and the theoretical values are well coherent with the test data.

Mechanical properties of near alpha titanium alloys for high-temperature applications - a review

Purpose This paper aims to present a broad review of near-a titanium alloys for high-temperature applications. Design/methodology/approach Following a brief introduction of titanium (Ti) alloys, this paper considers the near-α group of Ti alloys, which are the most popular high-temperature Ti alloys developed for a high-temperature application, particularly in compressor disc and blades in aero-engines. The paper is relied on literature within the past decade to discuss phase stability and microstructural effect of alloying elements, plastic deformation and reinforcements used in the development of these alloys. Findings The near-a Ti alloys show high potential for high-temperature applications, and many researchers have explored the incorporation of TiC, TiB SiC, Y2O3, La2O3 and Al2O3 reinforcements for improved mechanical properties. Rolling, extrusion, forging and some severe plastic deformation (SPD) techniques, as well as heat treatment methods, have also been explored extensively. There is, however, a paucity of information on SiC, Y2O3 and carbon nanotube reinforcements and their combinations for improved mechanical properties. Information on some SPD techniques such as cyclic extrusion compression, multiaxial compression/forging and repeated corrugation and straightening for this class of alloys is also limited. Originality/value This paper provides a topical, technical insight into developments in near-a Ti alloys using literature from within the past decade. It also outlines the future developments of this class of Ti alloys.