Dynamic compressive properties of lightweight engineered geopolymer composites containing ceramsite (LW-EGC)

In this paper, polyvinyl alcohol (PVA) fiber and multi-walled carbon nanotubes (MWCNTs) reinforced light-weight engineered geopolymer composites containing ceramsite (LW-EGC) were presented. The dynamic compressive response and microstructures of these LW-EGC under different steel fiber contents (0, 0.5, 1.0, and 1.5%) and strain rates (91.06 s- 1-255.79 s-1) were investigated. The dynamic compressive behavior of the LW-EGC was tested using a split Hopkinson pressure bar with a diameter of 100 mm. The microstructures of the LW-EGC and the failure modes of the hybrid fibers were analyzed. Compared with LW-EGC-C, when the steel fiber content was 1.0%, its quasi-static compressive strength and elastic modulus were increased by 39.28% and 15.32%, respectively. Under similar strain rates, the dynamic peak strain and dynamic compressive strength increased initially and subsequently decreased with an increase in the steel fiber content. The optimal content of steel fibers was 0.5%, and the peak strain and dynamic compressive strength were 0.77% and 94.54 MPa, respectively. Moreover, the dynamic mechanical properties of the LW-EGC indicated a significant strain rate enhancement effect. A negative correlation was noted between the steel fiber content and the dynamic increase factor. The DIF predicted by DIFPre was quite consistent with the experimental results, and can be used in the dynamic design of LW-EGC. Additionally, microscopy observations showed that steel fibers, PVA fibers, and functionalized MWCNTs bridged cracks at different scales and improved the impact resistance of the LW-EGC.