The Durability Of Reactive Powder Concrete Under The Coupling Effect Of Sulfate Dry-wet And Freeze-thaw

Reactive Powder Concrete is widely used in practical project due to its good mechanical properties and durability. In realistic environment, structure is generally affected by double factors of salt corrosion and cycles of freeze-thaw. It is lack of reliability to analyze durability of structure based on the results of single factor experiments. Therefore, the study of Reactive Powder Concrete properties under coupling effect of sulfate dry-wet and freeze-thaw has special significance.In the environment of coupling of sulfate dry-wet and freeze-thaw, the properties of ordinary concrete and Reactive Powder Concrete are investigated. After each single coupling cycle, the dynamic modulus of elasticity and mass of concrete prisms are measured. The influences of mineral admixtures, aggregates, steel fiber contents and initial damage on the durability of Reactive Powder Concrete are analyzed. The influences of river sand ratio and initial damage on the mechanical properties of Reactive Powder Concrete are also investigated through cube compressive strength test.In sulfate cycle of dry-wet and freeze-thaw, the relative dynamic elastic modulus of Reactive Powder Concrete is on the increase, however, after one sulfate cycle of dry-wet and freeze-thaw, the relative dynamic elastic modulus of C50ordinary concrete decreases. The relative dynamic elastic modulus of ordinary concrete is significantly lower than Reactive Powder Concrete after same number of cycle. While silica fume is replaced by fly ash in Reactive Powder Concrete, after same number of cycle, the relative dynamic elastic modulus decreases by the increasing of fly ash amount. The relative dynamic elastic modulus of Reactive Powder Concrete is increased by the increasing of steel fiber content. With simulating damage, the reactive powder concrete with pieces of plastic, its relative dynamic elastic modulus is decreasing along with the increase of plastic pieces after same number of sulfate cycle of dry-wet and freeze-thaw.In sulfate cycles of dry-wet and freeze-thaw, the compressive strength of C50concrete is decreasing along the increase of cycles, while the compressive strength of Reactive Powder Concrete has the tendency of increasing first and then decreasing and then increasing. The compressive strength of Reactive Powder Concrete reaches a maximum after2cycles of sulfate dry-wet and freeze-thaw, and a minimum after7cycles of sulfate dry-wet and freeze-thaw. While quartz sand is partly replaced by river sand, the compressive strength of Reactive Powder Concrete remained about the same after cycles of sulfate dry-wet and freeze-thaw. After the same number of cycles, the compressive strength deceases along with the increase of river sand. The compressive strength of Reactive Powder Concrete with simulating damage is decreasing after sulfate cycles of sulfate dry-wet and freeze-thaw. After the same number of cycles, the compressive strength deceases along with the increase of plastic pieces.