Performance Improvement and Design of UHDMC Using PE Fibers

In this chapter, ultra-high ductility magnesium phosphate cement-based composites (UHDMC) was prepared with the polyethylene (PE) fibers. The effect of the magnesium oxide to potassium dihydrogen phosphate mass ratio (M/P), quartz sand particle size (Sd), water to solid mass ratio (W/S), sand to binder mass ratio (S/B), fly ash (FA) content, fiber volume fraction (Vf), curing temperature, and curing age on the micro-mechanical properties and macro-mechanical properties of UHDMC were explored. The results showed that the ultimate tensile strain of UHDMC can reach 7.1%. Even curing at −10℃ for 7 days, the ultimate tensile strain can reach 5.6%, and the compressive strength can reach nearly 20 MPa. With the increase of M/P, the compressive strength of UHDMC increases, but the ultimate tensile stress decreases. The ultimate tensile strain of UHDMC with the Sd of 150–180 mesh can reach more than 5%. The large W/S is helpful to improve strain hardening performance. When the FA content is 40%, the strain hardening performance of UHDMC is significant, and the pseudo strain-hardening indices reach the maximum. The quantitative association model between ultimate tensile strain and pseudo strain-hardening indices was established. According to the association model, the design method of UHDMC was established.