超细粉煤灰和减水剂对碱激发粉煤灰胶凝材料的常温性能影响
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西安建筑科技大学

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Effect of ultra-fine fly ash and superplasticizer on properties of alkali-activated fly ash cementitious materials at room temperature
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1.Xi'2.'3.an University of Architecture and Technology

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    摘要:

    碱激发粉煤灰(AAFA)胶凝材料常温下聚合反应速度缓慢,无法满足现场施工的凝结硬化需求,本文利用超细粉煤灰常温制备AAFA胶凝材料并采用减水剂对其流动性能进行优化.结果表明,利用50%的超细粉煤灰取代一级粉煤灰制备的AAFA浆体(w/b=0.35),常温养护下的初凝时间为42 min,3d抗压强度为9.1 MPa,但由于表观黏度太大、常规试验测试不出流动度值.萘系减水剂可增强AAFA浆体中粉煤灰颗粒的分散,大幅降低表观黏度,显著提高浆体的初始流动度及流动度保持率,但会包裹粉煤灰颗粒并弱化凝胶产物间的连接,进而延长AAFA浆体的凝结时间,并对其早龄期的抗压强度不利.萘系-三聚氰胺复合减水剂亦可显著降低AAFA浆体的初始表观黏度、提升其初始流动度,却由于对浆体聚合反应进程的影响,使得浆体的流动度损失加快,并对其抗压强度发展产生一定的促进作用.

    Abstract:

    The very slow polymerization rate of alkali-activated fly ash (AAFA) cementitious material at room temperature cannot meet the setting and hardening requirements of on-site construction. In this paper, AAFA was prepared with ultra-fine fly ash at room temperature, and its flow performance was optimized by superplasticizer. The results showed that the AAFA paste prepared by replacing original fly ash with 50% ultra-fine fly ash exhibited the characteristics of rapid setting and high early strength at room temperature, and its initial setting time was 42 min, and the compressive strength at 3d was 9.1 MPa, while cannot flow with w/b at 0.35. Naphthalene superplasticizer enhanced the dispersion of fly ash particles in AAFA paste, significantly reduced the apparent viscosity, and thus improved the initial fluidity and fluidity retention of the paste, but encapsulated the fly ash particles and weakened the connection between the gel products, thereby prolonging the setting time of the AAFA paste and unfavorable to the compressive strength of the early age. Naphthalene- melamine composite superplasticizer also significantly reduced the initial apparent viscosity of AAFA paste and improved its initial fluidity. However, due to its influence on the polymerization process, the fluidity loss of AAFA paste was accelerated and the development of compressive strength was promoted.

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  • 收稿日期:2022-03-12
  • 最后修改日期:2022-05-05
  • 录用日期:2022-05-05
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