Abstract:

A cement mortar modifier， PB?g?PSG emulsion， was prepared with polybutadiene grafted styrene and glycidyl methacrylate as main raw materials and Tween?80 as a stabilizer， and cement mortar was modified by mixing cement and standard sand with PB?g?PSG emulsion and Tween?80. The micromorphology of the modified cement mortar was observed， and the effect of contents of Tween?80 and PB?g?PSG emulsion on the fluidity， mechanical properties， water retention rate and water absorption of the modified cement mortar were studied using scanning electron microscope， cement mortar fluidity tester and laser particle size analyzer. Meanwhile， the effect mechanism of Tween?80 for PB?g?PSG emulsion was analyzed. The results indicated that the modified cement mortar exhibited an excellent water retention with a maximum water retention rate of 99.3 %. The water absorption quality of modified cement mortar decreases at first and then increases with an increase in the Tween?80 content. The compressive strength of the modified cement mortar decreased gradually with an increase in the content of PB?g?PSG emulsion and was less than that of the unmodified cement mortar. The flexural strength of the modified cement mortar increased at first and then tended to decrease， which was essentially higher than that of the unmodified cement mortar. The modified cement mortar achieved the highest flexural strength of 9.52 MPa at a content of PB?g?PSG emulsion of 10 wt%. The PB?g?PSG emulsion can generate an adhesion and bridging effect on cement hydrate， and an interpenetrating network structure can be formed between them. The hydrophilic group in the Tween?80 molecules can adsorb water on the surface of PB?g?PSG emulsion particles and form a thick layer of hydration. In this case， the latex particles can be isolated from each other， avoiding the occurrence of condensation.

Key words: Twain?80, polybutadiene, styrene, grafting, epoxy propyl methacrylate, modification, cement mortar