钢纤维橡胶再生混凝土的抗冻性试验

Test of frost resistance for steel fiber rubber recycled concrete

为使废弃混凝土和再生橡胶在北方地区混凝土工程中得以应用,采用正交试验法研究再生粗骨料掺量、再生粗骨料强化方式、钢纤维掺量与橡胶掺量对钢纤维橡胶再生混凝土（C45）立方体抗压强度和抗冻性的影响规律.利用扫描电镜和螺旋CT扫描技术研究了钢纤维橡胶再生混凝土的宏观和细观结构及其对抗冻性能的影响机理.结果表明：橡胶颗粒掺量是影响再生混凝土含气量、抗压强度和相对动弹模量的重要因素,再生粗骨料掺量是影响相对动弹模量和强度损失率的次要因素,钢纤维掺量对混凝土抗压强度增强作用较小,粗骨料强化方式对混凝土性能影响不大;橡胶颗粒与砂浆界面的裂缝宽度在5～55 μm之间,二者之间的相容性较差;当橡胶颗粒掺量（与砂的体积比）大于20％后,随橡胶颗粒掺量增大,混凝土内部孔洞数目增多,钢纤维橡胶再生混凝土抗压强度降低、抗冻性减弱.

In order to make waste concrete and recycled rubber apply in concrete engineering in northern region, the effects of recycled coarse aggregates content, strengthening method of recycled coarse aggregates, content of steel fibers as well as content of rubber on compressive strength and frost resistance of steel fiber rubber recycled concrete （C45） were investigated by orthogonal design tests. Through the scanning electron microscopy and screw CT scan- ning technique, the macro and micro structure and their effect mechanisms on frost resistance of steel fiber rubber recycled concrete were analyzed. The results show that the content of rubber particles is a prominent factor affecting the gas content, compressive strength and relative dynamic elastic modulus of recycled concrete, and the content of recycled coarse aggregates is also an important factor affecting the relative dynamic elastic modulus and strength loss rate. In addition, the compressive strength of concrete increases slowly with the increase of steel fibers, and strengthening method of aggregates has almost no effect on the performance of concrete. The crack width between rubber particles and mortar interface falls into 5-55 μm. Compatibility between rubber particles and mortar interface is a little bad. When the content of rubber particles is above 20% （volume ratio between rubber particles and sands）, the inner hole number of concrete will rise with strength of steel fiber rubber recycled concrete will drop, the increase of rubber particle content. The compressive and frost resistance will also decrease.