Impact of micromechanics on dynamic compressive behavior of ultra-high performance concrete containing limestone powder

To improve sustainability and reduce costs, interest in using limestone powder (LP) ultra-high performance concrete (UHPC) has been increasing recent years. Incorporating LP changes packing, characteristics of C–S–H pore structure interfacial transition zone (ITZ) matrix by physical chemical effects. However, the influences replacement on mechanical properties UHPC, from micromechanics to macroscopic impact behaviors, have not well understood. Herein, mercury intrusion porosimetry (MIP), thermal gravimetric (TG), nanoindentation test Split Hopkinson pressure bar (SHPB) are performed reveal relationships between micromechanical dynamic performances UHPC. Results show that appropriate amount incorporation optimizes leading a narrower space more densely compacted improves percentages high-density density ITZ. The higher results steel fiber-matrix bond strength, which benefits compressive strength energy absorption while lower increase factor. More low-density generated due dilution effect excessive LP, weak deteriorates resistance. Additionally, mechanism enhancing quality ITZ is proposed, favors understanding relation macro behavior at micro nanoscale.