建筑垃圾再生骨料中杂质对其制备再生混凝土性能影响研究

Study on the Influence of Impurities in Recycled Aggregate of Construction Waste on the Performance of Recycled Concrete

为了降低建筑垃圾肆意堆放造成的围城风险,提高建筑垃圾高值资源化利用程度,增强再生材料工程安全性能,采用控制变量法,开展了建筑垃圾再生骨料杂质种类及含量对再生混凝土性能的影响研究。结果表明,在设计配合比条件下,建筑垃圾再生混凝土28d抗压强度满足C25强度等级要求,且具有较高的安全余量,表现出韧性强,抗变形性能好等力学特征。混凝土性能主要受再生骨料杂质含量、吸水性、粘合性、填充性等因素影响。其中,木屑和金属可显著提高混凝土浆体的粘聚性,降低流动性,最大降幅接近50%。而玻璃提高了混凝土拌料的流动度,最大增幅达32%。当玻璃掺入量达到6%时,混凝土28d抗压强度约18MPa,降幅接近50%,严重制约混凝土安全性。因此,建筑垃圾资源化利用时,应提高骨料除杂分选效率,降低再生骨料的含杂率,其杂质总含量宜低于3%,以保障再生混凝土的安全性及工作性。

In order to reduce the siege risk caused by indiscriminate stacking of construction waste, improve the high value utilization of construction waste resources, and enhance the safety performance of recycled materials engineering, the control variable method was used to carry out a study on the influence of the types and content of impurities in the recycled aggregate of construction waste on the performance of recycled concrete. The results showed that under the condition of design mix ratio, the 28d compressive strength of recycled concrete, prepared by using recycled aggregate produced from construction waste, can meet the strength grade requirements of C25 with a high safety margin, which shows strong toughness, good deformation resistance and other mechanical characteristics. Concrete performance is mainly affected by impurity content, water absorption, adhesion, filling and so on. Among them, wood chips and metal can significantly improve the cohesiveness of concrete slurry and reduce the fluidity, with a maximum reduction of nearly 50%. The other hand, glass addition increased the fluidity of concrete mixture by up to 32% due to its smooth surface. When the glass content reaches 6%, the 28d compressive strength of concreteis about 18MPa, the decrease is close to 50%, which seriously restricts the safety of concrete. Therefore, during construction waste resource utilization, it is significant to improve the efficiency of impurity separation and removal. The total impurity content of recycle aggregate should be controlled less than 3% to ensure the safety and working performance of recycled concrete.