A novel hydrophilic modification method of EPS particles: Conception design and performances in concrete

Due to the low density and the distinct surface hydrophobicity of EPS, EPS are prone to float in the mixing and forming process of EPS concrete and to distribute unevenly in the process of concrete hardening, which finally results in the poor mechanical properties of EPS concrete. To improve EPS hydrophilicity, a new modification method was proposed in this paper to graft Pluronic (PEO) and ammonium chloride (NH4Cl) with hydrophilic groups on EPS surface, thereby converting EPS from hydrophobicity to hydrophilicity. The effects of modification on both the EPS hydrophilicity and the working performance and mechanical properties of EPS concrete were studied. The results suggest that both the modified EPS hydrophilicity and the EPS concrete fluidity and uniformity were significantly improved, with the minimum hydrophilic angle of EPS of 29°, and the minimum quality difference between the upper and lower concrete parts of 4.7%. While at the final failure, unmodified EPS concrete presented the most severe damage, however, modified EPS concrete, remained relatively intact. Compared with unmodified EPS concrete, modified EPS concrete cube increased its compressive strength by 26.64%, and its flexural strength by 16.12%. The ascending section of the stress-strain curve shows a regular linear distribution, whereas its descending curve jittered down with slight fluctuations in load, owning to the resilience of EPS. In addition, each stress-strain curve was fitted by a two-stage method, which indicates a high overall fitting degree.