Experimental Study On Dynamic Mechanical Properties Of Concrete Under Circumferential Carbonation

Concrete is widely used in various infrastructure construction projects,and carbonization occurs due to CO2 in the air.In order to explore the dynamic mechanical properties of the concrete exposed to the air for a long time under accidental dynamic loads,the 3d,7d,14d,28d carbonization simulations of the concrete specimens are carried out using the carbonization box,and the impact compression and splitting tests are carried out with a 50mm diameter separated Hopkinson compression rod device to study the stress,strain and fracture characteristics of pneumatic concrete specimens with different carbonization ages and different impacts,the relations of dynamic peak strain,dynamic elastic modulus,dynamic compressive and tensile strength and fragmentation degree with carbonization age is analyzed.The research has achieved the following results:(1)In the compression test:under the same impact air pressure,with the increase of the carbonization age,the dynamic compressive strength and elastic modulus of the concrete specimens linearly increase,the peak strain linearly decreases,and the specimen failure form is Splitting tensile failure and the proportion of large-size fragments increased from about 60%to about 90%,an increase of nearly 30%;under the same carbonization age,with the increase of impact pressure,peak stress and peak strain will gradually Increased,the proportion of large particle size fragments of the specimen decreased by about 3%.(2)In the splitting test:Under the same carbonization age,the peak stress and peak strain gradually increase with the continuous increase of the impact air pressure,and the degree of fragmentation of the specimen is also increasing.The proportion is reduced by about 2%;under the same impact air pressure,with the increase of carbonization age,the tensile strength and elastic modulus of concrete also increase,but the peak strain gradually decreases,and the specimen is broken.On the contrary,the smaller the degree,the proportion of large-size fragments rose from about 75%to about 95%,an increase of nearly 20%,and the dynamic tensile strength was higher.(3)Both compression and splitting tests show that the incident energy,reflected energy and transmission energy of the concrete specimens gradually increase with the increase of time under different impact pressures and the same carbonization age;at different carbonization ages,the same Under the impact air pressure,the incident energy,reflected energy and transmission energy of the concrete specimens also gradually increase with time.Before 50μs,the incident energy increases slowly;after 50μs,the incident energy quickly increases to the peak and remains stable,and the energy absorption rate is mostly between 10%and 40%.Figure[43]Table[12]Reference[73]...