Study on preparation and early strength property of modified nano-MgO complexed TEA composite cement materials

In this study, nano-magnesium oxide (MgO) was modified with surfactants sodium polyacrylate, polyvinyl alcohol (PVA) and polyethylene glycol (PEG) based on the agglomeration problem of nano-MgO in cement. The surfactant PEG with the best modification effect was selected to modify nano-MgO and synergize with the dispersing effect and early-strengthening effect of triethanolamine (TEA) to prepare a new type of composite cementitious sealing material with high early compressive strength and good fluidity. The optimal ratio of the mass fraction of the composite early-strengthening agent was determined by the response surface method: 0.02% PEG + 2% nano-MgO + 0.04% TEA. The effects of the composite early-strengthening agent on the cementitious sealing material were investigated by the compressive strength, fluidity, setting time, X-ray diffraction experiments (XRD), thermogravimetric (TG-DSC), scanning electron microscopy (SEM), etc. The effect of the composite early-strengthening agent on the cementitious sealing material was also investigated by the response surface method. The compressive strength of the composite cement specimens at 1d, 3d, and 7d was increased by 92.59%, 35.50%, and 47.73% respectively compared to the blank group. In comparison to the control group, the flowability increased by 31.96%, and the initial and final setting time was shortened to 377 min and 394 min, respectively.