Effects of bacteria-embedded polylactic acid (PLA) capsules on fracture properties of strain hardening cementitious composite (SHCC)

Strain hardening cementitious composite (SHCC) is a special class of ultra-ductile material which has autogenous self-healing capability due to its intrinsic tight crack widths. To further improve healing ability, agent (HA) can be incorporated in SHCC, enabling it also the autonomous mechanism. In this study, effects adding bacteria-embedded polylactic acid (PLA) capsules on mechanical properties SHCC with different amounts HA (i.e., 1.25%, 2.5%, 5% by weight binder) were investigated. Experiments conducted examine performance, matrix and single fiber pullout behavior SHCCs, followed microscopy characterization fiber/matrix interface microstructure. Results show that inclusion PLA-HA up binder influenced tensile performance strength ductility) only very small extent but significantly reduced average residual The at high dosage (5%) increased tip toughness (Jtip) lowering elastic modulus increasing fracture toughness. Single results bond enhanced addition HA, attributed formation denser interfacial transition zone (ITZ) less calcium hydroxide crystals as revealed scanning electron microscope (SEM) micrographs. improved led higher bridging complementary energy thus partially sustained strain capacity verified micromechanical model.