Preparation technology, mechanical properties and durability of coral aggregate seawater concrete in the island-reef environment

For the island-reef engineering construction background in the South China Sea, the research studied the preparation technology, mechanical properties and chloride ion diffusion behavior of coral aggregate seawater concrete and discussed the steel bars corrosion behavior of coral aggregate seawater concrete (CASC) and reliability analysis of service life, which provide a low cost, high durability CASC and its application technology for island-reef engineering. The results showed that: according to the theory of grout concrete and the design principle of high-performance concrete, the cube compressive strength (f(cu)) of CASC can reach C80. Uniaxial compression whole stress-strain curve of CASC with different strength grades and constitutive relation were obtained. The three high Cl- diffusion characteristics, high initial chloride ion content (C-0), high surface chloride ion content (C-s) and high apparent chloride ion diffusion coefficient (D-a) in CASC, were established, which easily result in steel bars corrosion. It suggests to choose organic newly coated steel bars, which the thickness of the concrete protective cover is greater than 5.5 cm, concrete strength grade is greater than C50 and use slow-release effect of micropump of coral aggregate to pre-absorb and incorporate the amino alcohols inhibitor, which can significantly reduce steel bars corrosion of CASC structures. Finally, the study determined the durability design methods of CASC structures that meet the 20-100 years of service life requirement.

Automated summary

This research focuses on the preparation technology, mechanical properties, and chloride ion diffusion behavior of coral aggregate seawater concrete (CASC) in the background of island-reef engineering construction in the South China Sea. It also discusses the corrosion behavior of steel bars in CASC as well as the reliability analysis of its service life. The study provides a low-cost and high-durability CASC and its application technology for island-reef engineering. The research findings show that CASC can achieve a cube compressive strength of C80. Furthermore, the study establishes the high Cl- diffusion characteristics in CASC, which can easily result in steel bars corrosion. It suggests using organic newly coated steel bars, a concrete protective cover thickness greater than 5.5 cm, and the slow-release effect of micropump of coral aggregate to reduce steel bars corrosion.