Effect of Bubble Structure Modifying Agent on Fluidity and Compressive Strength of AirEntrained Mortar

Abstract:

Two representative kinds of bubble structure modifying agents were selected to study the effect of different types of bubble structure modifying agent on the fluidity and compressive strength of the airentrained mortar. The mechanism of the bubble structure modifying agent on the fluidity and compressive strength of the airentrained mortar was researched by testing pore structure parameters of the hardened airentrained mortar with bubble structure modifying agent and the surface tension of the liquid. The results show that the viscosity modifying agent, cyclodextrin (βCD), can delay the airentraining process by increasing the liquidphase viscosity of the mortar, so that the bubbles (pores) in the mortar can be refined, the porosity of air void size ranging from 10 μm to 20 μm can be raised, and the fluidity and compressive strength of the mortar can be increased. The antifoaming agent, siloxane polyether copolymer (PSPEO), can replace the airentraining agent molecules on the surface of the bubbles film and reduce the local surface tension. The big bubbles are refined into small bubbles with lowdosage PSPEO, while the strength of the gasliquid interface film is reduced, bubbles cannot exist stably with highdosage PSPEO and the total porosity is lowered. Therefore, the fluidity of the mortar first increases and then decreases, and the compressive strength continuously increases.