Analysis of microstructure of concretes utilized under marine environments

The evolution of microstructure of concretes utilized under marine environments was studied by microhardness, SEM, XRD, MIP and 29Si MAS NMR. The results showed that concrete under marine environments is apt to be destroyed by dissolution or expansion damage due to the roles of gypsum and ettringite easily gathering in interface transition zone. Slag-incorporated Concrete is obviously less porous and the mechanical properties of the interface transition zone are enhanced. However, with the slag content of more than 30%, the pore refining effect is less significant and the distribution of pore diameter is bipolarized, the harmless pores and much harm pores are obviously increased, while harmful pores and less harm pores are reduced. There exist [SiO4] tetrahedrons of hydration products in forms of Q3 and Q4 in addition to the forms of Q1, Q2 and Q2 (1Al), which can be resulted from the reduced resonance frequency of 29Si and the chemical shift with a shift to negative. ©, 2015, Journal of Functional Materials. All right reserved.