建筑废弃物再生粗骨料表面改性试验研究

Experimental Study on Surface Modification of Recycled Coarse Aggregate of Construction Waste

再生骨料高吸水率和低强度的特征限制了其应用。针对此,本研究使用硅酸钠溶液和硅烷溶液以浸渍改性方法对再生粗骨料进行表面改性,研究了改性剂的浓度、种类、浸渍处理时间、再生骨料的类型以及粒径对改性再生骨料性能的影响,并对表面改性机理进行了分析。结果表明,两种改性剂均可有效提高再生骨料表观密度,降低其吸水率和压碎指标。当硅酸钠溶液浓度为8%、硅烷溶液浓度为10%时,改性效果更好;原始再生骨料的性能越差,改性效果越显著;10~31.5 mm粒径再生骨料的改性效果优于5~10 mm粒径再生骨料的改性效果。硅酸钠溶液与再生骨料表面粘附的废砂浆反应生成的产物物理填充再生骨料表面孔隙和微裂缝的改性效果优于硅烷溶液在骨料表面形成憎水包裹膜层的改性效果。

The high water absorption and low mechanical strength of recycled aggregate limit its utilization. Aiming at these problems,sodium silicate and silicane solution are applied to modify the surface of recycled aggregate respectively in the method of dipping modification. The influence of different kinds and concentration of modifier,the dipping time,the types and particle size of recycled aggregate on the performance of modifying recycled aggregate are studied in this contribution. Meanwhile,the modification mechanism is discussed. Experiment results indicates that the apparent density of recycled aggregate increase in the presence of two kinds of modifier effectively whereas water absorption rate and crush value of recycled aggregate reduced at the same time; the modification performance is better while the concentration of sodium silicate solution is8%and silicane solution is 10%; the worse performance of the original recycled aggregate,the better the effect of modification; the modification effect of 10~31. 5 mm particle size recycled aggregate is superior than that of5~10 mm. Furthermore,the physical modification influence of sodium silicate solution reacts with waste mortar at recycled aggregate surface generated product which filled recycled aggregate surface pore and micro cracks is superior than that of silicane solution formed hydrophobic layer on aggregate surface.