etyylihydroksietyyliselluloosa
Mailose ME 40K(S)
The setting time of concrete is mainly related to the setting time of cement, and the aggregate has little effect, so the setting time of mortar can be used instead of studying the effect of HP cellulose on the setting time of underwater non dispersible concrete mixture. Since the setting time of mortar is affected by water cement ratio and cement sand ratio, in order to evaluate the effect of HP cellulose on the setting time of mortar, it is necessary to fix the water cement ratio and cement sand ratio of mortar.
The working mechanism of methyl hydroxyethyl cellulose, MHEC (Mw = 2.5 · 105 g/mol, DSmethyl = 1.81, MShydroxyethyl = 0.15) as water retention agent in cement was investigated. First, the hydrocolloid was characterized and its performance as non-ionic water retention agent was determined employing the filter paper test. Also, water sorption and swelling of individual MHEC fibers under conditions of different humidities were monitored by ESEM imaging. Second, its working mechanism was established. It was found that at low dosages, MHEC achieves water retention by intramolecular sorption of water and concomitant swelling while at higher dosages, MHEC molecules agglomerate into large hydrocolloidal microgel particles (d > 1 μm) which effectively plug the pores in the mortar matrix. MHEC association was evidenced by an exponential increase in solution viscosity as concentration rises, a strong increase in the hydrodynamic diameter of solved MHEC molecules, and a noticeable reduction of surface tension.