| The chloride corrosion of marine engineering will make the performance of reinforced concrete structure failure ahead of time,and the chloride binding behavior of cement hydration products will delay the transmission of chloride ions.Therefore,the research on the chloride binding ability of single hydration product has reference significance for the durability evaluation of marine engineering reinforced concrete structure.Based on the difference of phase content and degradation rate under carbonization,a new method was proposed to obtain the chloride binding capacity of single hydration product in actual hydration system(1)The influence of mineral admixtures on the chloride binding capacity was studied.It was found that incorporation of fly ash could increase the content of C-S-H gel and reduce the content of Friedel’s salt,which could enhance the binding capacity of chlorine ion when suitable dosage was added,but it would play a negative role when the dosage was too large.Mineral powder can not only enhance the gel content of C-S-H but also increase the content of Friedel’s salt,so it can significantly enhance the binding capacity of chlorine ion when suitable dosage is added,but it will also play a negative role when the dosage is too large.Although silica fume can also enhance the content of C-S-H gel,but the reduction effect on Friedel ’s salt content is obvious,so the increase of its dosage will reduce the chloride ion binding capacity,but it does not exclude the possibility of improving the binding capacity when the amount of micro silica is added.The chloride binding capacity of the samples with different mixing ratios increased with the increase of chloride concentration.(2)The effect of carbonization degree on the chloride binding capacity of cement paste was studied.It was found that the carbonation effect reduced the content of C-S-H gel and Friedel ’s salt,resulting in the decrease of the total chloride binding capacity of the slurry.The addition of mineral admixtures made the paste more carbonized and magnified this effect.(3)Based on the decomposition effect of carbonization,a new method for calculating the chloride binding capacity of single phase in cement hydration system is proposed.By this method,the chloride ion binding quantity of C-S-H gel of unit mass is calculated to be between 10.25 and 21.46 mg,and the contribution to the total chloride ion binding capacity of the slurry is between 33.3～78.9%,fly ash,mineral powder,and so on.The incorporation and carbonization of silica fume will reduce the chloride ion binding capacity of C-S-H gel.The chloride ion binding capacity per unit mass of Friedel’s salt is 106.86～726.98 mg.The appropriate amount of admixture can improve the chloride ion binding capacity of Friedel’s salt,and the improvement effect of mineral powder is the most obvious(4)C-S-H gel,AFm and AFt were synthesized and their chloride binding ability was studied,which verified the reliability of the new method proposed in this study.The chloride binding capacity of the synthesized C-S-H gel increased first and then decreased with the increase of Ca/Si.The binding capacity of the synthesized gels was the strongest when the ratio of calcium to silicon was 1.4.The chloride binding ability of synthetic AFm is higher than that of synthetic C-S-H gel,and the binding capacity of AFt to CL is the worst. |
