The influence of mineral admixtures on workability of fresh concrete and chloride ion permeability resistance of hardened concrete for C50 self-compacting concrete was investigated by means of the Natural Immersion Test. The results showed that the chloride diffusion coefficient in fly ash concrete decreased first and then increased with increasing fly ash content in cementitious materials, when fly ash content was 30% or 40%, it got the lowest value at 28 days or 90 days, respectively. The chloride diffusion coefficient in specimens decreased with increasing the ground granulated blast furnace slag content in cementitious materials, but it changed little when the replacement was in ranges of 50% to 60%. Furthermore, for the specimens which replaced by fly ash and ground granulated blast furnace slag, the chloride diffusion coefficient decreased first and then increased with increasing the fly ash content in complex cementitious, and when fly ash content was 10% or 20%, it got the lowest value at 28 days or 90 days, respectively.

The influence of stone dust content on chloride diffusion coefficient in C30, C40 and C50 grade concretes were investigated by means of the natural immersion test, XRD test, MIP test, SEM and TGA test, respectively. The experimental results showed that the chloride diffusion coefficient in C30 grade concretes decreased with increasing the stone dust content, but it decreased first and then increased with increasing the stone dust content in C40 and C50 grade concretes. The hydration degree for cementitious and compressive strength for concrete was slightly promoted by using stone dust replacing cementitious at a low level. For C30 grade concretes, the porosity decreased with increasing the stone dust content in fine aggregate, but for C40 and C50 grade concretes, the total porosity decreased first then increased with increasing the stone dust content. And the concrete pore structure was the main factor that influences the changes of chloride diffusion coefficient in concrete.

Self-compacting concrete often requires greater liquidity, and the big liquidity is easy to cause the concrete segregation. Thickener can effectively improve the rheological properties of concrete, namely appropriately increase plastic viscosity, but does not significantly affect concrete liquidity. The compatibility of polyacrylamide (PAM), carboxymethyl cellulose (CMC) in the cementitious material system was studied. The influence of thickener on liquidity, 7d strength, 28d strength and shrinkage in cementitious materials system were analyzed.

The influence of complex admixture on chloride diffusion coefficient of C50 self-compacting concrete for marine environment was investigated by means of the NT BUILD 443 Test, and the influence mechanism of complex admixture on the diffusion coefficient was studied, respectively. The results showed that the chloride diffusion coefficient decreased first and then increased with increasing the fly ash content in complex cementitious, and when fly ash content was 10% or 20%, it got the lowest value at 28 days or 90 days, respectively. Its more helpful to promote the fly hydration degree for extending curing period. Furthermore, the porosity and average pore size decreased first but then increased with increasing the fly ash content in complex cementitious, the porosity and average pore size got the lowest value when the fly ash content was 20% in cementitous.

The influence of mineral admixtures on chloride threshold value was investigated by EIS method, MIP test and TG test, respectively. The experimental results showed that the chloride threshold value decreased with increasing the fly ash and slag content in composite cementitious. The increasing of fly ash and slag replacement resulted in the decreasing of porosity, average pore size and Ca(OH)2content. The effect of mineral admixtures on the chloride threshold value was the comprehensive results of concrete pore structure and Ca(OH)2content. The chloride threshold value decreased with decreasing the Ca(OH)2content in concrete, and there was an approximate linear relationship between the logarithm of chloride threshold value and the logarithm of CCa(OH)2content when the specimens exposed in tidal zone. The specimen exposed in tidal zone has a higher chloride threshold value than that exposed in splash zone was due to the lower dissolved oxygen around steels in concrete.