Study on the mechanism of polymer inhibiting purplish soil fugitive dust at macro–micro scale in Southwest China

Polymers with good adhesion properties are typically used as soil fugitive dust suppressants in infrastructure construction. This study investigates the dust suppression effect of hydroxypropyl guar gum (HPG), polyacrylamide (PAM), and starch (STA), as well as analyses their bonding mechanism on soil fugitive dust surface via laboratory experiments and molecular simulations. Laboratory test results indicate that the viscosity of HPG solution is the highest. At a mass concentration of 0.35 %, the maximum viscosity recorded is 288.5 mPa∙s, which is 44.8 and 264.08 mPa∙s higher than those of PAM and STA solutions, respectively. The wind-erosion resistance rate of soil fugitive dust samples treated with HPG is 98.63 %, which is 2.66 %, 3.51 %, and 30.43 % higher than those of PAM, STA, and water, respectively. The water-erosion rate of soil fugitive dust samples treated with HPG is only 2.06 %, which is 0.52 %, 1.05 %, and 12.11 % lower than those of PAM, STA, and water, respectively. HPG exhibits excellent cohesiveness and effectively inhibits the generation of soil fugitive dust. Molecular simulation results show that the adsorption energy of HPG is 4.8 %–48.3 % and 3.2 %–54.8 % lower than those of PAM and STA, respectively, thus indicating the higher adsorption capacity of HPG. The distribution of HPG on the surface of soil fugitive dust components is the most concentrated. The self-diffusion coefficient of HPG is 0.3–6.7 and 1.2–12.4 times lower than those of PAM and STA, respectively; therefore, the structures of the HPG/soil fugitive dust component simulation systems are more stable. The radial distribution function shows that the van der Waals force is the primary force affecting the molecular dynamics behaviour, which signifies physical adsorption. The binding mechanism of polymers on the surface of soil fugitive dust is that the polymer approaches the surface of soil fugitive dust through van der Waals forces and eventually adsorbs onto the surface of soil fugitive dust to bond with it. This study provides a theoretical foundation for the development of more effective soil fugitive dust suppressants for infrastructure construction.