粉煤灰品质和取代率对再生混凝土抗冻性能影响

Influence of Quality and Substitution Rate of Fly Ash on Anti-freeze Performance of Recycled Coarse Aggregate Concrete

根据《混凝土用再生粗骨料》(GB/T 25177-2010),通过颗粒整形技术,将废弃砂石骨料制成Ⅰ类标准再生粗骨料。再生粗骨料全部取代天然骨料,粉煤灰按比例(=0%、10%、20%、30%)取代水泥制成粉煤灰类再生混凝土,研究粉煤灰品质和取代率对再生混凝土抗冻性能的影响。结果显示:Ⅰ级粉煤灰再生混凝土>Ⅱ级粉煤灰再生混凝土,且随着胶凝材料用量增多,粉煤灰再生混凝土的抗冻性能提高。增加粉煤灰掺量,Ⅱ级粉煤灰再生混凝土能经受的冻融次数呈减小趋势,毛细吸水量成增大趋势,表明Ⅱ级粉煤灰削弱了再生混凝土抗冻性能,Ⅰ级粉煤灰再生混凝土的抗冻性能先增大后减小。

According to Recycled Coarse Aggregate for Concrete(GB/T 25177-2010),the waste concrete is particle-reshaped to recycled coarse aggregate of class I. The recycled coarse aggregate completely replaces the natural one, and the fly ash, a substitute of cement, is made into fly ash recycled concrete with proper proportion (=0%, 10%, 20%, 30%), to study the influence of quality and substitution rate of fly ash on anti-freeze performance of recycled coarse aggregate concrete. The results show that class I fly ash recycled concrete>class II fly ash recycled concrete, and with the increase of cementitious materials, the anti-freeze performance of fly ash recycled concrete is improved. With the amount of fly ash rising, the number of freeze-thaw cycles that can be experienced by class II fly ash recycled concrete decreases is reducing and the capillary water absorption is increasing, which indicate that class II fly ash weakens the anti-freeze resistance of recycled concrete, and that of class I fly ash recycled concrete increases first and then decreases.