Research On Durability And Life Prediction Of Recycled Aggregate Of Self-compacting Concrete With Steel Slag

At present,the annual output of steel slag is very large in China,but the comprehensive utilization of steel slag is very low,a large number of steel slag can not be effectively used,causing serious pollution.With the development of green building materials,people began to gradually pay attention to the comprehensive utilization of steel slag.Thus,a series of research on recycled aggregate of self-compacting concrete with steel slag(RASCCSS)were conducted by the studying team.On the basis of,carbonization resistance and chloride ion penetration resistance of the recycled aggregate of self-compacting concrete with steel slag are studied by carbonation test and chloride ion permeation test in this paper.The effects of different factors are analyzed,the life prediction model of concrete was established.In addition,the interaction between carbonization and chloride penetration with different steel slag content was studied.The main conclusions are reached as follows:1.The carbonization depth of RASCCSS has a tendency to decrease first and then increase with the increase of steel slag rate.Moreover,the influence of steel slag content on the carbonization depth of RASCCSS is same,regardless of curing time.With the increase of curing time,the carbonization resistance of RASCCSS is gradually improved.When the steel slag content is 10%,the carbonization resistance of RASCCSS is the best.2.With the change of steel slag rate,the chloride ion permeability of RASCCSS has a different change law in different curing age.When the curing age is 7 days and 14 days,the chloride ion diffusion coefficient of RASCCSS shows an increasing tendency with the increase of steel slag content.When the curing age is 28 days,56 days and 90 days,when the steel slag content is 10%,the chloride ion permeability of RASCCSS is the best.With the increase of steel slag content,the chloride ion diffusion coefficient of RASCCSS shows a trend of decreasing first and then increasing.3.The one is carbonation modeling based on multi-factors,which content of steel slag,curing age andvariability of concrete cover,especially with time change of CO2 diffusion coefficient are considered in the modeling.The other is new multi-factors service life prediction modeling for concretes,which included the chloride ions mainly.The modeling based on Fick's second diffusion law,considered steel slag,curing age,variability of concrete cover.The establishment of the model will provide the basis for the service life prediction of RASCCSS.4.The comparative tests show that carbonation can reduce the chloride ion diffusion coefficient,and the chloride ion penetration can enhance the carbonization resistance.