利用粉煤灰级配提高混凝土力学性能

研究了Ⅲ级粉煤灰及3种不同细度的磨细灰的掺量对混凝土拌合物力学性能的影响，结果表明:磨细粉煤灰中的亚微米颗粒越多，早期活性越高；但粉煤灰的过度细化会造成坍落度大幅度下降.SEM形貌分析表明，在28 d时，Ⅲ级粉煤灰的玻璃微珠并未发生水化反应.利用Andreasen方程探索了不同细度粉煤灰之间级配的协同作用效应，证明了Ⅲ级粉煤灰的微集料效应对混凝土强度起主要贡献.在考虑实际生产和应用中的制约因素情况下，对粉煤灰掺量为50%的混凝土进行4阶混料设计，导出了以坍落度、28 d抗压强度为函数的回归方程.

Improved mechanical properties of concrete by fly ash grading

Mechanical properties of concrete influenced by dosage of different fineness class Ⅲ fly ash was researched. The result shows that activity in early phase elevated as amount of submicron particle increased in grinding fly ash. Over grinding resulted in slump decrease sharply. The SEM analysis shows that hydrated products of glass micronbeads in class Ⅲ fly ash is not founded. Synergistic effect between different fineness fly ash is researched by Andreasen equation. Micro aggregate effect is the most important factor affects the strength of concrete. Fourth order mixture design is studied with the replacement of cement by fly ash were 50% under the condition of practical production and application. The regression equation which uses slump and compressive strength at 28 d as function was deduced.