非引气法提高混凝土抗冻性的效果及机理

Improving the frost resistance of concrete without air entraining agent

引气法提高抗冻性有着含气量不易控制与降低强度及耐磨性等缺点。在非引气试验中,消泡剂的掺入能在搅拌及搅拌后一段时间取代原液膜,致使气泡膜应力失衡;而膨胀剂的作用机理则为产生膨胀性物质以填充钙矾石骨架,二者的掺入都起着提高水泥基复合材料密实度的效果,提高了强度和抗冻性。但消泡剂掺量过大会降低水泥颗粒间的引力,对强度不利;膨胀剂掺量过大会造成后期膨胀性产物对已成结构的破坏,形成内部微裂纹,出现反效果。

There are many disadvantages in using air entraining agent to improve the frost resistance of concrete,such as the reducing of strength,abrasion resistance and controllability.However,these issues would be solved by another method which is using expansive agent and defoarner.The former can cause stress imbalance of the bubble film while the latter can produce ettringite in the concrete,both of which are contribute to the density.In this way,the strength as well as the frost resistance of the concrete would be improved.Additionally, the volume should be controlled strictly.