Study on the mechanical properties and durability of recycled fly ash concrete with different substitution rates for construction
Using waste concrete as recycled aggregate,Grade I fly ash was treated with wet grinding to prepare recycled concrete with different replacement rates of fly ash.The effects of different substitution rates of Grade I fly ash on the mechanical and durability properties of recycled concrete were studied through XRD,SEM,me-chanical performance testing,and dry shrinkage testing.The results show that the glass body on the surface of fly ash after wet grinding treatment is destroyed,and the volcanic ash effect is enhanced,thus improving the hydration rate of recycled concrete,increasing the number of hydration products C-S-H and AFt,and in-creasing the compactness of concrete.The compressive strength of fly ash recycled concrete first increases and then decreases with the increase of fly ash replacement rate.The maximum compressive strength of concrete with a 45％fly ash replacement rate is 42.05 MPa,and the content of its hydration product Ca(OH)2 is up to 11.742％.The deflection test shows that the yield stage of concrete with a 45％replacement rate of fly ash cor-responds to a load of 217 N,with a maximum deflection of 1.7 mm.The minimum dry shrinkage of concrete with a 45％replacement rate of fly ash at 28 d is 1.021×10-4.Overall,it can be concluded that concrete with a 45％replacement rate of fly ash has the best performance.
万方数据
维普
