引气方式对水泥基材料性能的影响

Effects of air-entraining methods on properties of cement-based materials

对比研究了掺铝粉和引气剂两种引气方式对新拌和硬化水泥基材料性能的影响。实验结果表明:掺引气剂引入的气泡能通过滚珠效应改善砂浆流动性,而掺铝粉因发气与砂浆稠化过程同步,对初始流动度无明显影响。掺铝粉和引气剂引入的球形气孔均可有效减小砂浆干燥收缩,掺引气剂时,随着掺量增大,3 d和90 d干缩均呈先减小后增大趋势;掺铝粉时,随着掺量增大,3 d干缩持续减小,90 d干缩呈先减小后增大趋势。当含气量较低时,相同含气量下掺引气剂减缩效果更明显;当含气量较高时,掺铝粉减缩效果更明显;当含气量相同时,掺铝粉的砂浆强度较高。

The effects of two air-entraining methods,including aluminum powder and air-entraining agent,on the properties of fresh and hardened cement-based materials are compared.The results show that air bubbles introduced by air-entraining agent can improve the fluidity of mortar through the ball effect,while aluminum powder has no obvious effect on the initial fluidity due to the synchronization of gas generation and the thickening process of mortar.The spherical pores introduced by both aluminum powder and air-entraining agent can effectively reduce the drying shrinkage of mortar.When air-entraining agent is used,the drying shrinkage at both 3 d and 90 d shows a trend of first decreasing and then increasing.When aluminum powder is introduced,the drying shrinkage at 3 d continues to decrease,while that at 90 d also shows a trend of first decreasing and then increasing.When the air content is small,the shrinkage reduction effect is more obvious while incorporating air-entraining agent than that with aluminum powder for a given air content.When the air content is high,the shrinkage reduction effect of aluminum powder is more obvious.For a given air content,the strength of mortar with aluminum powder is higher than that with air-entraining agent.