Study On Mechanical Behavior Of Coral Aggregate Concrete Under Impact Load

Since the 18th CPC National Congress put forward the"maritime power"strategy,infrastructure construction,national defense engineering,reef engineering have developed rapidly.The required building materials are also increasing year by year.However,the South China Sea Islands and reefs are far away from the mainland.The transportation of a large number of raw materials requires huge costs,and there are many unsafe factors.There are many advantages in using coral as aggregate for preparing concrete,such as saving cost and shortening construction period.In this paper,MTS quasi-static press was used to carry out quasi-static compression tests on coral aggregate concrete（CAC）and ordinary portland cement（OPC）.In addition,dynamic compression tests of CAC and OPC were carried out with SHPB device.The main conclusions are as follows:（1）In terms of static mechanics,under the same mix proportion,the compressive strength of CAC and lightweight aggregate concrete（LAC）is lower than that of OPC.Under the same strength,the elastic modulus of CAC was between lac and OPC.In addition,the failure interface of coral aggregate is in coral aggregate,which is quite different from OPC.The brittleness of CAC is more obvious than that of OPC,which is close to that of lac.Finally,the energy dissipation coefficient of OPC is obviously greater than that of LAC and CAC.（2）In the aspect of dynamic mechanics,the CAC and OPC under four strain rates were tested by SHPB testing device system.In addition,sieving test were carried out on crushed samples.The results show that the peak stress of CAC is significantly higher than that of OPC,because the free water in CAC enhances the cementation between coral aggregate and mortar under high-speed impact.When the strain rate is166s^-1,the particle size evolution of OPC tends to be stable,while the particle size evolution of CAC has not been completed.At the same strain rate,the dynamic increase factor（DIF）of CAC is higher than that of OPC,and the DIF of C45 CAC is between C30 CAC and C60 CAC.Furthermore,the empirical equation of DIF of CAC at different strain rates was proposed.From the perspective of energy dissipation,the impact toughness of CAC is lower than that of OPC before the stress peak.（3）In the aspect of numerical simulation,the experimental failure mode of CAC was similar to that of numerical simulation,and the specimens show four failure modes.Based on the Holmquist-Johnson-cook（HJC）model,the dynamic mechanical behavior of CAC is effectively simulated.