Research On The Influence Of Mixing Station Waste On Premixed Concrete Properties

The commercial concrete industry gets fast development with the promotion of infrastructure construction in China.Plenty of premixed concrete waste,created by concrete premixing stations,can't get suitable disposal without appropriate cyclic utilization technology.It's a wasting of resources while polluting the environment.Proceed from the basic properties of premixed concrete waste and its impact on properties of concrete,we did some researches on concrete waste cyclic utilization according to the analysis of theory and practice systematically.With relate field study,we designed a circulation system,including washing,sieving,subside,transport,and did trial application on pilot enterprise.In order to use these premixed concrete waste on new concrete mixing,we did correlative tests for the waste to get the basic parameter to guarantee it meet the concrete standards.Subside of these concrete waste was separated into two parts,supernatant liquor and substrate paste.We discussed its impacts on cement mortar properties by changing the content of solid of substrate paste.The results showed the waste had no significant influence on mortar strength.For supernatant liquor,the mortar strength changed with the dosage of it.The influences of concrete wastes with different solid content on fresh properties and mechanical properties of concrete are similar and all of these have a limit doped amount.Meanwhile,it showed no obvious effect on air content of concrete.This thesis did some comparative study on durability,such as permeability,carbonization and frost resistance of the concrete prepared with these concrete wastes.The test results indicated that the replacement use of premixed concrete waste can increase the anti-permeability and carbonation resistance of new concrete.It showed no negative effects on frost resistance.Several microscopic test methods,such as XRD,SEM,MIP,were introduced to do supplementary analysis on the impacts of waste on concrete properties from hydration process and reaction dynamics.