再生混凝土冻融循环试验与损伤模型研究

FREEZ-THAW CYCLE TEST AND A DAMAGE MECHANICS MODEL FOR RECYCLED CONCRETE

对废弃混凝土进行破碎后所得的骨料称为再生骨料,按再生粗骨料掺量为40%的配比进行混凝土冻融循环试验,并结合聚丙烯纤维和引气减水剂两个配比参数对其抗冻影响机理的分析,得到不同掺量下聚丙烯纤维和引气减水剂对再生混凝土抗冻耐久性的影响,以及冻融后再生混凝土内部损伤变量的变化规律。结果表明:掺加聚丙烯纤维和引气减水剂可使设计强度等级为C30的再生混凝土达到F200以上的抗冻等级,并能有效地抑制其冻融损伤劣化,且引气减水剂的掺加效果更为明显。根据再生混凝土冻融破坏机理,进行再生混凝土冻融损伤分析并建立冻融损伤模型,模型所预测的再生混凝土损伤程度符合工程实际冻融破坏情况。

Aggregate obtained by breaking wasted concrete is called recylcled aggregate. Freeze-thaw cycle tests were carried out on recycled aggregate concrete （RAC） containing 40% of recycled coarse aggregate. Mixed with polypropylene fiber and gas-lifting water-reducing （GLWR） agent, its frost resistance durability and inner damage distribution were also analyzed. It is shown that frost resistance rating of F200 can be achieved from C30 RAC by mixing polypropylene fiber and GLWR-agent. The mixture is also effective in preventing freeze-thaw damage deterioration, where GLWT-agent was more effective. A freeze-thaw damage mechanics model was then established. And predictions from the model agree well with the actual engineering observations.