Experimental study of multiscale hybrid fiber-reinforced ambient-cured LEGC under uniaxial compression

This study proposed the addition of cellulose nanofibers (CNFs) and basalt fibers (BFs) as hybrid fibers (HFs) into lightweight expanded polystyrene (EPS) geopolymer concrete (LEGC) to enhance its mechanical properties from chemical and physical perspectives. First, uniaxial compression tests were performed on LEGC specimens with moderate densities (1120-1920 kg/m3) reinforced with HF prepared with different CNF weight ratios (0.1%, 0.2%, and 0.3%) and fixed BF volume content of 0.6%. The test results demonstrated that the integrity of the specimens under the effect of the suitable dosing of HF was better maintained at final destruction, and the enhancement rates of the compressive strength and elastic modulus of the specimens with HF were superior to those with a single fiber type. The suitable dose of CNF was 0.2% for EPS volume contents of 10% and 20%, while 0.1% was suitable for EPS volume contents of 30% and 40%. Meanwhile, the cracking resistance mechanism of HF specimens was analyzed from chemical and physical perspectives, and the synergistic mechanism was determined quantitatively. In addition, the enhancement rates of the energy absorption capacity of the specimens with a suitable dose of HF were also more effective, which ensured the light weight of the material and improved its energy absorption capacity. Finally, this study developed a nine-parameter damage constitutive model that could better describe the five-stage characteristics of the complete stress[sbnd]strain curve of the specimens, providing a certain theoretical basis for the structural design and analysis of LEGCs.