Effects of hydroxyethyl methyl cellulose ether on the hydration and compressive strength of calcium aluminate cement

Abstract

Aluminate containing phases such as tricalcium aluminate (C3A) and dodecacalcium heptaaluminate (C12A7) play a key role in the reaction between Portland cement and cellulose ether. In order to simplify such impact from calcium aluminate, calcium aluminate cement (CAC) was applied as a carrier. Effects of hydroxyethyl methyl cellulose ether (HEMC) on the hydration of CAC were characterized by means of isothermal calorimetry, X-ray diffraction analysis, thermal analysis and scanning electron microscopy, respectively. Meanwhile, the setting times, water retention, air content and compressive strengths of HEMC modified CAC pastes or mortars were also determined. Results indicate that HEMC prominently delays the hydration of CAC within 1 day, and the higher dosage of HEMC, the longer setting times. HEMC exerts no obvious impact on the formation amount of CAH10, only leads to a smaller crystal size. From aspect of physical and mechanical properties, the addition of HEMC improves the water retention of fresh CAC mortars, and only with addition of 0.1% HEMC, the water retention of fresh CAC mortars almost approaches 100%. Additionally, the addition of HEMC also significantly promotes the air content of fresh CAC mortars, leading to an obvious decrease in the compressive strengths.